Air quality

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Air quality problems such as smog and acid rain result from the release of pollutants into the atmosphere. The majority of these pollutants come from human activities, such as transportation, the burning of fuels for electricity and heating, and industry. Natural sources such as forest fires can sometimes be substantial. Air pollutants cause adverse health and environmental effects.

The Air quality indicators present the annual averages of 5 key air pollutants for Canada and 5 large regions. Comparison of the averages to the Canadian Ambient Air Quality Standards (the standards) is for illustrative purposes only. An average that is below the standards does not imply that air pollutant levels are below the standards in all areas of Canada. Please consult the Canadian Council of Ministers of the Environment State of the air report for information on how air pollutant levels in areas of Canada compare to the standards.

National

Air quality trends in Canada

Key results

Between 2002 and 2016

  • nitrogen dioxide (NO2), sulphur dioxide (SO2), volatile organic compounds (VOC) and peak ground‑level ozone (O3) concentrations decreased
  • average O3 concentrations showed almost no change
  • fine particulate matter (PM2.5) concentrations exhibit variable results

Air pollutant concentrations, Canada, 2002 to 2016

Air pollutant concentrations, Canada, 2002 to 2016 (see data tables below for the long description)
Data tables for the long description
Air quality indicators relative to the 2002 concentrations, Canada, 2002 to 2016
Year Ground-level ozone average 8-hour concentration
(percentage change relative to 2002)
Ground-level ozone peak (4th highest) 8-hour concentration
(percentage change relative to 2002)
Fine particulate matter average concentration
(percentage change relative to 2002)
Fine particulate matter peak (98th percentile) 24-hour concentration
(percentage change relative to 2002)
2002 0.0 0.0 0.0 0.0
2003 2.0 -0.6 -0.7 -1.5
2004 -3.1 -12.4 -10.7 -8.7
2005 0.5 -7.1 -5.8 -2.3
2006 -0.3 -9.5 -14.9 -23.8
2007 1.1 -5.3 -16.0 -18.8
2008 -0.9 -11.8 -15.8 -27.1
2009 -3.1 -15.8 -18.3 -33.0
2010 0.9 -12.6 -6.6 -10.1
2011 1.2 -16.0 -8.7 -24.9
2012 3.1 -10.9 -9.6 -27.5
2013 1.3 -17.0 -0.7 -24.4
2014 0.9 -20.2 3.3 -15.0
2015 0.3 -13.4 2.5 -14.2
2016 -0.9 -16.7 -12.2 -24.4
Air quality indicators relative to the 2002 concentrations, Canada, 2002 to 2016
Year Sulphur dioxide average concentration
(percentage change relative to 2002)
Sulphur dioxide peak (99th percentile) 1-hour concentration
(percentage change relative to 2002)
Nitrogen dioxide average concentration
(percentage change relative to 2002)
Nitrogen dioxide
peak
(98th percentile) 1-hour concentration
(percentage change relative to 2002)
Volatile organic compounds concentration
(percentage change relative to 2002)
2002 0.0 0.0 0.0 0.0 0.0
2003 -6.5 -1.7 1.8 -2.4 31.3
2004 -19.3 -1.1 -10.9 -4.2 18.9
2005 -21.0 3.7 -12.3 -3.9 -7.2
2006 -23.9 -3.4 -17.9 -8.2 0.9
2007 -22.5 -6.9 -18.3 -11.2 -4.6
2008 -30.7 -7.9 -20.5 -13.0 -7.1
2009 -40.2 -18.8 -25.4 -14.6 -0.5
2010 -47.8 -17.0 -30.4 -15.9 -11.7
2011 -46.4 -40.0 -31.0 -18.2 -17.2
2012 -48.0 -38.1 -36.7 -21.6 -27.9
2013 -52.7 -40.3 -36.2 -23.1 -23.0
2014 -54.7 -44.7 -36.6 -23.5 -28.7
2015 -59.7 -47.8 -38.6 -22.9 -25.7
2016 -63.5 -51.7 -42.7 -24.8 -36.1
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How this indicator was calculated

Note: For more information on the Air quality indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program and the Canadian Air and Precipitation Monitoring Network.

More information

In 2016, average SO2 concentrations were 64% lower than in 2002. Peak SO2 concentrations fell below the 2002 level in 2006 and by 2016, were 52% below the 2002 concentration.

The average O3 concentration has not changed substantially since 2002. In 2016, it was 1% lower than in 2002. In 2016, the peak O3 level was 17% below the 2002 concentration.

The average PM2.5 concentrations were higher in 2014 and 2015 than in 2002. In 2016, the average PM2.5 concentration was 12% lower than in 2002. In 2016, the peak PM2.5 concentration was 24% below the 2002 levels.

Average and peak NO2 concentrations, respectively, were 43% and 25% lower in 2016 than in 2002.

VOC concentrations were below the 2002 level except in 2003, 2004 and 2006. In 2016, the VOC concentration was 36% below the 2002 level.

The levels of these pollutants in outdoor air are influenced by many factors, including the proximity to local emission sources, weather conditions, chemical reactions in the air and the transport of air pollutants over long distances by wind. Part of the increase in the fine particulate matter concentrations recorded since 2009 may be due to the progressive introduction of monitoring equipment based on newer technologies and to increase in forest fire events in the past decade. This is especially true for the peak fine particulate matter concentrations recorded in Western Canada.

Air quality concentrations relative to the Canadian Ambient Air Quality Standards

Key results

When compared to the 2020 Canadian Ambient Air Quality StandardsFootnote 1 

  • national concentrations of fine particulate matter (PM2.5), sulphur dioxide (SO2) and nitrogen dioxide (NO2) have been below their respective standards since 2002
  • peak ozone (O3) concentrations were above the standard only at the beginning of the period

Air pollutant concentrations relative to the Canadian Ambient Air Quality Standards, Canada, 2002 to 2016

Air pollutant concentrations relative to the Canadian Ambient Air Quality Standards, Canada, 2002 to 2016 (see data tables below for the long description)
Data tables for the long description
Air quality indicators relative to the Canadian Ambient Air Quality Standards, Canada, 2002 to 2016
Year Ground-level ozone peak (4th highest) 8-hour concentration
(percentage change relative to the 2020 standard)
Fine particulate matter average
concentration
(percentage change relative to the 2020 standard)
Fine particulate matter
peak (98th percentile)
24-hour concentration
(percentage change relative to the 2020 standard)
2002 10.0 -17.3 -4.0
2003 9.3 -17.9 -5.5
2004 -3.7 -26.1 -12.4
2005 2.1 -22.1 -6.3
2006 -0.5 -29.6 -26.9
2007 4.1 -30.5 -22.1
2008 -3.0 -30.3 -30.0
2009 -7.4 -32.4 -35.7
2010 -3.9 -22.8 -13.8
2011 -7.7 -24.5 -28.0
2012 -2.1 -25.3 -30.5
2013 -8.8 -17.9 -27.5
2014 -12.2 -14.6 -18.4
2015 -4.8 -15.2 -17.7
2016 -8.4 -27.4 -27.4
Standard 62 parts per billion 8.8 microgram per cubic metre 27 micrograms per cubic metre
Air quality indicators relative to the Canadian Ambient Air Quality Standards, Canada, 2002 to 2016
Year Sulphur dioxide average concentration (percentage change relative to the 2020 standard) Sulphur dioxide peak (99th percentile) 1-hour concentration (percentage change relative to the 2020 standard) Nitrogen dioxide average concentration (percentage change relative to the 2020 standard) Nitrogen dioxide peak (98th percentile) 1-hour concentration (percentage change relative to the 2020 standard)
2002 -43.8 -13.1 -19.4 -13.9
2003 -47.4 -14.5 -18.0 -16.0
2004 -54.7 -14.0 -28.2 -17.6
2005 -55.6 -9.9 -29.3 -17.3
2006 -57.2 -16.0 -33.9 -21.0
2007 -56.4 -19.0 -34.2 -23.6
2008 -61.0 -20.0 -35.9 -25.1
2009 -66.4 -29.4 -39.9 -26.5
2010 -70.7 -27.9 -43.9 -27.6
2011 -69.9 -47.8 -44.4 -29.6
2012 -70.8 -46.2 -49.0 -32.5
2013 -73.4 -48.1 -48.6 -33.8
2014 -74.5 -52.0 -48.9 -34.2
2015 -77.4 -54.6 -50.5 -33.6
2016 -79.5 -58.0 -53.8 -35.3
Standard 5 parts per billion 70 parts per billion 17 parts per billion 60 parts per billion
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How this indicator was calculated

Note: The horizontal line at 0% represents the reference level of the 2020 Canadian Ambient Air Quality Standards. Comparison of the national concentrations to the Canadian Ambient Air Quality Standards is provided for illustrative purposes only. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program and the Canadian Air and Precipitation Monitoring Network.

More information

Peak O3 concentrations were mainly above the standard before 2008 but have been below the standard since then. In 2016, the peak concentration was 8% below the standard.

In 2016, average and peak levels of PM2.5 were 27% below the corresponding standards. Average and peak levels of sulphur dioxide were 80% and 58% below the respective standards, while the average and peak levels of nitrogen dioxide were 54% and 35% below their respective standards.

The indicators are shown relative to the Canadian Ambient Air Quality Standards for illustrative purposes only and not for assessing the achievement status of the standards.Footnote 2

By pollutant
Fine particulate matter

Fine particulate matter

Fine particulate matter (PM2.5) is emitted to the air and can also form in the air through the interactions of other pollutants. The particles can be in solid or liquid form. Fine particulate matter is one of the major components of smog. When inhaled deeply into the lungs, even small amounts of PM2.5 can cause serious health problems. The particles can also damage vegetation and structures, contribute to haze and reduce visibility.

Average concentrations of fine particulate matter
Peak concentrations of fine particulate matter

Key resultsFootnote 3

Between 2002 and 2016

  • the annual average and annual peak concentration of PM2.5 were below their respective 2020 standardsFootnote 4 
  • no trends, either increasing or decreasing, were found over the period

Fine particulate matter concentrations, Canada, 2002 to 2016

Fine particulate matter concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Fine particulate matter concentrations, Canada, 2002 to 2016
Year Average concentration
(micrograms per cubic metre)
Peak (98th percentile) 24-hour concentration
(micrograms per cubic metre)
2002 7.3 25.9
2003 7.2 25.5
2004 6.5 23.6
2005 6.9 25.3
2006 6.2 19.7
2007 6.1 21.0
2008 6.1 18.9
2009 6.0 17.4
2010 6.8 23.3
2011 6.6 19.5
2012 6.6 18.8
2013 7.2 19.6
2014 7.5 22.0
2015 7.5 22.2
2016 6.4 19.6
2020 standard 8.8 27.0
Annual trend No trend No trend
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How this indicator was calculated

Note: The average PM2.5 concentration indicator is based on the annual average of the daily 24-hour average concentrations for PM2.5 recorded at 109 monitoring stations across Canada. The national peak indicator is based on the 98th percentile of the daily 24-hour average concentrations for PM2.5 recorded at 114 monitoring stations across Canada. The horizontal dashed lines represent the 2020 Canadian Ambient Air Quality Standards. The Canadian Ambient Air Quality Standards are provided for illustrative purposes only and not for assessing the achievement status of the standards. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the national average concentration of PM2.5 was 6.4 micrograms per cubic metre (µg/m3), a level 14% lower than in 2015. The national peak concentration of PM2.5 in 2016 was 19.6 µg/m3, which is 12% lower than in 2015.

Changes in PM2.5 levels may be related to changes in the quantity of emissions and to annual variations in weather conditions. Weather conditions influence the formation, dispersion and regional transport of PM2.5 as well as transboundary movement of PM2.5 from the United States. The variations observed in the concentrations of PM2.5 were also influenced by the progressive introduction of monitoring equipment based on newer technologies.

Average concentrations of fine particulate matter

Regional ambient levels

Key results

  • Since 2002, average PM2.5 concentrations have consistently remained below the 2020 standardFootnote 5 across all regions of Canada, except for the first 2 years in southern Quebec
  • An increasing trend was detected for the average PM2.5 concentrations in Atlantic Canada and the Prairies and northern Ontario region. A decreasing trend was found for southern Quebec

Regional average fine particulate matter concentrations, Canada, 2002 to 2016

Regional average fine particulate matter concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional average fine particulate matter concentrations, Canada, 2002 to 2016
Year Atlantic Canada average concentration
(micrograms per cubic metre)
Southern Quebec average concentration
(micrograms per cubic metre)
Southern Ontario average concentration
(micrograms per cubic metre)
Prairies and northern Ontario average concentration
(micrograms per cubic metre)
British Columbia average concentration
(micrograms per cubic metre)
2002 4.8 9.8 8.5 5.8 6.6
2003 4.6 9.7 8.3 5.6 6.8
2004 4.0 7.9 7.5 4.5 6.1
2005 4.3 8.4 8.6 4.1 5.6
2006 4.0 7.0 7.2 4.8 5.5
2007 4.0 7.1 7.3 4.6 5.0
2008 4.5 8.2 6.6 4.5 5.0
2009 5.0 8.3 5.6 4.6 5.3
2010 5.0 8.4 6.0 7.8 5.7
2011 6.0 8.4 6.1 7.7 4.8
2012 5.0 8.3 6.0 7.2 5.3
2013 5.7 8.0 7.9 6.8 6.0
2014 6.0 7.8 8.1 7.3 6.9
2015 6.0 7.4 7.9 7.7 7.2
2016 5.6 6.3 6.6 7.7 5.3
2020 standard 8.8 8.8 8.8 8.8 8.8
Annual trend 0.13 -0.14 No trend 0.18 No trend
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How this indicator was calculated

Note: The average PM2.5 concentration indicator is based on concentrations recorded at 8 monitoring stations in Atlantic Canada, 28 in southern Quebec, 33 in southern Ontario, 20 in the Prairies and northern Ontario region, and 19 in British Columbia. The horizontal dashed line represents the annual standard of the 2020 Canadian Ambient Air Quality Standards. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing the achievement status of the standard. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the Prairies and northern Ontario region had the highest PM2.5 concentration, at 7.7 µg/m3. British Columbia had the lowest concentration, at 5.3 µg/m3. Forest fires in the Fort McMurray area in 2016 may have contributed to the higher levels in the Prairies and northern Ontario region.

All regions had lower concentrations in 2016 than in 2015. In 2016, British Columbia and southern Ontario recorded the largest reductions in concentrations, with a decrease of 26% and 17%, respectively, from the 2015 level. For British Columbia, very high levels were recorded in the previous 2 years, possibly due to extensive forest fires. Southern Quebec recorded a decrease of 15% in 2016 while Atlantic Canada and the Prairies and northern Ontario region posted reductions of 7% and 1%, respectively.

No trends were detected for southern Ontario or British Columbia. While a decreasing trend of 0.1 µg/m3 per year was observed in southern Quebec, increasing trends were detected in Atlantic Canada and in the Prairies and northern Ontario region, with values of 0.1 µg/m3 per year and 0.2 µg/m3 per year, respectively.

Urban areas

Key results

In 2016, among the selected urban areas

  • Windsor, Quebec City and Regina recorded the highest average concentrations of PM2.5
  • Whitehorse, Charlottetown and Victoria recorded the lowest concentrations

Average fine particulate matter concentrations, selected Canadian urban areas, 2016

Average fine particulate matter concentrations, selected Canadian urban areas, 2016 (see data tables below for the long description)
Data tables for the long description
Average fine particulate matter concentrations, Canadian urban areas, 2002 to 2009
Urban area 2002
(micrograms per cubic metre)
2003
(micrograms per cubic metre)
2004
(micrograms per cubic metre)
2005
(micrograms per cubic metre)
2006
(micrograms per cubic metre)
2007
(micrograms per cubic metre)
2008
(micrograms per cubic metre)
2009
(micrograms per cubic metre)
Whitehorse, YT 2.4 2.4 4.8 2.8 n/a n/a 1.8 n/a
Charlottetown, PE n/a n/a n/a n/a n/a n/a n/a n/a
Victoria, BC 6.1 5.2 5.8 5.8 5.7 5.1 4.1 5.3
Vancouver, BC 5.5 5.5 5.4 5.5 4.9 4.6 4.5 5.0
Halifax, NS 4.1 n/a 5.7 4.4 n/a 3.1 3.6 4.5
Sherbrooke, QC n/a n/a 7.6 7.9 6.9 6.5 7.0 6.2
St. John's, NL 4.8 4.3 3.7 4.0 3.5 2.8 3.3 4.5
Calgary, AB 6.3 8.1 6.4 5.5 6.6 5.7 5.7 8.1
Gatineau, QC n/a n/a 6.8 7.5 6.1 6.0 5.9 5.1
Winnipeg, MB 6.0 5.5 4.4 4.6 4.9 4.7 4.5 4.4
Ottawa, ON 7.5 7.2 6.5 7.5 6.1 5.9 5.2 4.5
Fredericton, NB n/a 5.1 4.1 4.3 4.4 3.8 3.9  3.8
Oshawa, ON 9.1 7.8 7.9 n/a 6.8 6.8 6.3 5.2
Edmonton, AB 6.3 6.6 5.5 4.9 5.6 5.4 5.8 5.9
London, ON n/a 9.4 9.2 10.3 8.0 6.9 6.8 5.7
Saskatoon, SK n/a n/a 3.7 3.6 4.1 3.6 4.0 4.0
St. Catharines – Niagara, ON n/a 7.8 7.3 8.6 7.8 8.2 7.4 6.0
Toronto, ON 8.6 8.4 7.8 9.0 7.6 7.7 7.1 5.6
Montreal, QC 10.0 10.5 8.7 10.0 7.7 7.5 11.6 10.9
Kitchener, ON n/a 8.2 8.1 9.5 7.7 8.0 7.1 5.8
Hamilton, ON 11.2 9.6 8.7 9.6 8.3 8.0 7.5 6.3
Yellowknife, NT n/a n/a n/a 3.3 1.4 1.9 5.1 4.3
Regina, SK 7.3 7.3 4.5 4.2 4.6 4.5 4.6 4.9
Quebec City, QC 7.8 8.0 7.8 9.3 8.1 6.7 7.1 n/a
Windsor, ON n/a 9.0 9.0 10.5 8.7 9.7 8.6 7.3
Average fine particulate matter concentrations, Canadian urban areas, 2010 to 2016
Urban area 2010
(micrograms per cubic metre)
2011
(micrograms per cubic metre)
2012
(micrograms per cubic metre)
2013
(micrograms per cubic metre)
2014
(micrograms per cubic metre)
2015
(micrograms per cubic metre)
2016
(micrograms per cubic metre)
Whitehorse, YT 1.9 2.5 5.6 6.2 n/a 5.5 3.4
Charlottetown, PE n/a n/a n/a n/a n/a 3.8 n/a
Victoria, BC 8.2 7.9 7.0 7.5 5.9 6.3 4.3
Vancouver, BC 4.0 4.2 4.1 6.1 6.1 6.1 4.5
Halifax, NS 4.5 6.0 5.4 6.7 7.0 4.3 5.0
Sherbrooke, QC 6.8 6.8 7.1 6.5 6.8 6.4 5.0
St. John's, NL 5.0 5.9 3.8 5.3 7.0 5.8 5.1
Calgary, AB 11.4 10.9 10.0 8.1 8.2 8.5 5.2
Gatineau, QC 6.0 7.2 8.3 6.8 6.8 6.1 5.6
Winnipeg, MB 5.8 7.2 6.7 6.2 5.8 6.0 5.8
Ottawa, ON 4.4 4.7 4.9 7.1 6.9 6.9 5.8
Fredericton, NB 3.9 5.2 4.8 4.2 5.2 5.8 5.8
Oshawa, ON 5.6 5.4 5.5 7.4 7.7 7.5 5.9
Edmonton, AB 10.0 7.0 6.5 6.6 7.7 7.1 6.4
London, ON 5.9 6.1 6.1 8.3 8.5 8.2 6.8
Saskatoon, SK 6.9 5.4 5.8 6.4 8.2 10.6 6.8
St. Catharines – Niagara, ON 6.5 6.3 6.3 8.5 n/a 8.5 6.9
Toronto, ON 6.1 6.4 6.3 8.3 8.8 8.5 7.0
Montreal, QC 10.3 10.2 9.8 9.8 8.8 8.5 7.1
Kitchener, ON 6.3 6.2 6.1 8.7 n/a 8.8 7.3
Hamilton, ON 6.7 7.0 7.1 9.3 10.0 9.7 7.8
Yellowknife, NT n/a 6.2 6.2 6.4 15.8 8.5 7.8
Regina, SK 7.3 7.7 6.1 6.6 6.6 11.0 8.1
Quebec City, QC 9.8 9.2 10.1 9.3 9.2 9.1 8.2
Windsor, ON 7.8 7.8 7.5 9.6 10.4 9.5 8.3

Note: n/a = not available.

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How this indicator was calculated

Note: Census metropolitan areas and census agglomerations were used to define the larger urban areas for this indicator. Only the 25 urban areas with sufficient data for the most populated municipalities in Canada and the provincial and territorial capitals are included. The Charlottetown concentration is for the year 2015. Concentrations for the years 2002 to 2016 are reported in the data table for this chart.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information
Fine particulate matter concentrations in Canadian urban areas differ from one location to another and from one year to the next. These differences are partly due to differences in emissions of pollutants, variations in weather conditions that influence PM2.5 formation, dispersion and regional transport, and variations in transboundary flows of pollution mainly from the United States. Exceptional events, such as forest fires, can also impact the average PM2.5 concentrations measured in urban areas.

Average fine particulate matter concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the average PM2.5 concentrations at specific monitoring stations.

Average fine particulate matter concentrations by monitoring station, Canada, 2016

Average fine particulate matter concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the average concentrations of fine particulate matter in 2016 by monitoring station. Stations are categorized by the concentration of fine particulate matter measured in the air. The categories are as follows: 0 to 4 micrograms per cubic metre, 4 to 6 micrograms per cubic metre, 6 to 8 micrograms per cubic metre, 8 to 8.8 micrograms per cubic metre and 8.8 micrograms per cubic metre or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program

Peak concentrations of fine particulate matter

Regional ambient levels

Key results

  • In 2016, peak concentrations of PM2.5 were below the 2020 standardFootnote 5 in all regions except the Prairies and northern Ontario region
  • Over the 2002 to 2016 period, southern Quebec and southern Ontario recorded decreasing trends in PM2.5 peak concentration, whereas the Prairies and northern Ontario region posted an increase

Regional peak fine particulate matter concentrations, Canada, 2002 to 2016

Regional peak fine particulate matter concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional peak fine particulate matter concentrations, Canada, 2002 to 2016
Year Atlantic Canada peak (98th percentile) concentration
(micrograms per cubic metre)
Southern Quebec peak (98th percentile) concentration
(micrograms per cubic metre)
Southern Ontario peak (98th percentile) concentration
(micrograms per cubic metre)
Prairies and northern Ontario peak (98th percentile) concentration
(micrograms per cubic metre)
British Columbia peak (98th percentile) concentration
(micrograms per cubic metre)
2002 18.4 35.2 31.9 18.3 19.9
2003 15.1 36.4 28.1 18.6 24.8
2004 13.0 26.3 30.1 15.6 18.2
2005 14.4 34.4 33.1 12.5 15.9
2006 12.7 22.2 23.5 15.4 16.7
2007 14.5 23.1 27.7 13.8 15.2
2008 14.0 23.3 21.3 13.3 15.1
2009 14.9 23.8 15.0 13.6 17.5
2010 13.8 25.6 21.4 25.2 26.7
2011 16.3 21.6 18.2 27.5 13.3
2012 12.7 22.8 17.2 20.2 16.9
2013 16.6 21.4 20.1 19.7 15.7
2014 13.6 19.2 21.4 24.5 22.4
2015 14.2 19.7 20.6 34.5 20.1
2016 11.8 16.1 16.5 37.9 13.7
2020 standard 27.0 27.0 27.0 27.0 27.0
Annual trend No trend -1.06 -1.01 1.13 No trend
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How this indicator was calculated

Note: The peak PM2.5 indicator is based on the concentrations recorded at 8 monitoring stations in Atlantic Canada, 28 in southern Quebec, 35 in southern Ontario, 20 in the Prairies and northern Ontario region, and 19 in British Columbia. The horizontal dashed line represents the 24-hour standard of the 2020 Canadian Ambient Air Quality Standards. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing the achievement status of the standard. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the highest concentration was found in the Prairies and northern Ontario region, at 37.9 µg/m3, which is 10% higher than in 2015. Atlantic Canada had the lowest annual peak concentration of PM2.5, at 11.8 µg/m3, which is 17% lower than in 2015. Forest fires in the Fort McMurray area in 2016 likely contributed to the increased levels in the Prairies and northern Ontario region.

Between 2002 and 2016, peak concentrations of PM2.5 were below the standard in 2 regions, specifically Atlantic Canada and British Columbia. Concentrations in southern Quebec and southern Ontario were above the standard in most years between 2002 and 2007, but remained below the standard from 2008 to 2016, while the Prairies and northern Ontario region posted concentrations above the standard in 2011 and in the last 2 years of the time series. Forest fires are the main reason why the concentrations exceeded the standards in the Prairies.

No trends were detected for Atlantic Canada and British Columbia. A decreasing trend of 1.0 µg/m3 and 1.1 µg/m3 per year, respectively, was found in southern Ontario and southern Quebec, while an increasing trend was detected in the Prairies and northern Ontario region (1.1 µg/m3 per year).

Urban areas

Key results

In 2016, among the selected urban areas

  • Regina, Quebec City and Saskatoon had the highest peak concentrations of PM2.5 in Canada
  • urban areas in Atlantic Canada and British Columbia had the lowest concentrations

Peak fine particulate matter concentrations, selected Canadian urban areas, 2016

Fine particulate matter peak concentrations, selected Canadian urban areas, 2016 (see data tables below for the long description)
Data tables for the long description
Peak fine particulate matter concentrations, Canadian urban areas, 2002 to 2009
Urban area 2002
(micrograms per cubic metre)
2003
(micrograms per cubic metre)
2004
(micrograms per cubic metre)
2005
(micrograms per cubic metre)
2006
(micrograms per cubic metre)
2007
(micrograms per cubic metre)
2008
(micrograms per cubic metre)
2009
(micrograms per cubic metre)
St. John's, NL 11.1 12.2 9.5 10.1 8.1 7.1 9.0 12.8
Halifax, NS 15.0 n/a 15.4 14.9 n/a 15.3 9.7 13.9
Vancouver, BC 15.6 16.1 14.6 14.7 13.3 12.6 13.0 13.6
Victoria, BC 16.4 12.9 13.7 13.3 13.0 16.1 10.4 14.8
Fredericton, NB n/a 18.8 13.5 16.1 15.4 16.8 14.8 15.6 
Sherbrooke, QC n/a n/a 27.5 26.6 21.4 20.3 18.5 17.7
Calgary, AB 18.8 35.3 17.6 13.2 18.3 16.2 14.5 18.5
Winnipeg, MB 19.5 14.1 13.1 14.7 14.5 12.0 13.0 12.3
Gatineau, QC n/a n/a 25.1 34.6 20.5 20.8 18.7 15.3
London, ON n/a 30.3 33.7 34.0 24.3 27.1 22.2 15.9
Whitehorse, YT 7.6 8.5 46.5 12.8 n/a n/a 7.6 n/a
St. Catharines – Niagara, ON 32.6 24.5 28.5 32.6 28.0 32.1 21.7 15.2
Oshawa, ON 34.3 25.0 30.0 n/a 24.3 29.1 20.8 14.4
Ottawa, ON 28.1 26.3 23.3 33.6 19.9 20.4 16.8 13.2
Kitchener, ON n/a 29.1 33.0 34.5 23.3 29.5 22.0 15.2
Toronto, ON 31.7 30.5 32.6 34.6 24.7 28.7 22.3 14.6
Montreal, QC 35.7 39.2 27.6 42.0 23.9 24.4 31.8 30.7
Hamilton, ON 33.3 30.0 32.6 33.8 26.1 29.0 24.5 16.0
Windsor, ON 37.2 29.6 32.1 32.3 24.4 29.4 22.8 18.3
Edmonton, AB 20.8 20.6 18.7 13.0 16.4 15.0 17.6 16.5
Yellowknife, NT n/a n/a 43.2 11.0 4.6 12.8 28.5 11.2
Saskatoon, SK n/a n/a 10.2 8.7 15.1 10.6 10.4 10.3
Quebec City, QC 29.0 28.2 23.5 34.1 22.8 23.7 20.5 n/a
Regina, SK 17.9 17.9 12.0 12.0 17.0 12.6 10.8 12.0
Peak fine particulate matter concentrations, Canadian urban areas, 2010 to 2016
Urban area 2010
(micrograms per cubic metre)
2011
(micrograms per cubic metre)
2012
(micrograms per cubic metre)
2013
(micrograms per cubic metre)
2014
(micrograms per cubic metre)
2015
(micrograms per cubic metre)
2016
(micrograms per cubic metre)
St. John's, NL 12.8 11.5 9.7 14.6 15.2 12.4 10.3
Halifax, NS 14.6 15.4 13.7 16.8 13.9 11.3 10.6
Vancouver, BC 12.1 9.9 12.3 14.4 15.9 16.1 10.7
Victoria, BC 20.0 21.5 16.2 21.8 18.8 18.4 11.8
Fredericton, NB 15.0 16.6 15.3 14.5 13.0 16.2 12.0
Sherbrooke, QC 20.9 17.5 16.9 16.6 16.9 16.4 13.4
Calgary, AB 30.8 24.0 21.9 20.8 21.2 26.1 14.1
Winnipeg, MB 16.4 18.0 19.5 21.3 18.0 20.6 14.5
Gatineau, QC 20.6 19.1 21.2 19.6 16.6 17.1 15.1
London, ON 20.9 17.6 16.9 20.4 21.1 20.5 15.5
Whitehorse, YT 6.3 7.5 17.8 19.9 n/a 18.3 15.6
St. Catharines – Niagara, ON 23.2 18.5 16.5 19.5 n/a 20.3 15.6
Oshawa, ON 22.5 17.5 15.3 20.4 18.9 20.4 16.6
Ottawa, ON 16.0 13.3 14.6 21.2 20.1 19.9 16.8
Kitchener, ON 21.0 17.5 17.2 22.5 n/a 23.2 17.8
Toronto, ON 22.2 18.7 17.7 20.7 24.5 22.8 18.3
Montreal, QC 30.4 26.0 27.6 25.3 22.6 23.0 18.3
Hamilton, ON 23.6 20.7 20.6 23.3 24.6 24.0 18.4
Windsor, ON 22.8 21.8 19.0 22.8 24.2 22.4 18.8
Edmonton, AB 34.4 21.0 18.6 21.1 22.6 22.0 19.6
Yellowknife, NT n/a 25.8 15.2 31.9 130.9 31.6 19.7
Saskatoon, SK 20.4 14.5 17.4 17.3 22.7 36.4 21.4
Quebec City, QC 27.6 22.9 28.5 25.7 22.6 25.4 21.4
Regina, SK 19.8 16.4 13.9 14.3 18.2 76.8 22.9

Note: n/a = not available.

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How this indicator was calculated

Note: Census metropolitan areas and census agglomerations were used to define the larger urban areas for this indicator. Only the 25 urban areas with sufficient data for the most populated municipalities in Canada and the provincial and territorial capitals are included. Concentrations for the years 2002 to 2016 are reported in the data table for this chart.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information
Fine particulate matter concentrations in Canadian urban areas differ from one location to another and from one year to the next. These differences are partly due to emissions of pollutants, variations in weather conditions that influence PM2.5 formation, dispersion and regional transport, and variations in transboundary flows of pollution mainly from the United States. Exceptional events, such as forest fires, can also have a significant influence on the peak PM2.5 concentrations in urban areas. Forest fires in the Fort McMurray area in 2016 likely contributed to the higher levels in the Prairies (Regina and Saskatoon).

Peak fine particulate matter concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the peak PM2.5 concentrations at specific monitoring stations.

Peak fine particulate matter concentrations by monitoring station, Canada, 2016

Peak fine particulate matter concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the peak concentrations of fine particulate matter in 2016 by monitoring station. Stations are categorized by the concentration of fine particulate matter measured in the air. The categories are as follows: 0 to 10 micrograms per cubic metre, 10 to 15 micrograms per cubic metre, 15 to 20 micrograms per cubic metre, 20 to 27 micrograms per cubic metre and 27 micrograms per cubic metre or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

Ground-level ozone

Ground-level ozone

Ozone (O3) in the upper atmosphere (10 to 50 kilometres above the earth's surface) protects the earth from the sun's harmful ultraviolet radiation. In the lower atmosphere and at ground level, O3 is harmful to human health, contributes to smog and can damage vegetation and materials such as rubber or surface coatings.

Average concentrations of ozone
Peak concentrations of ozone

Key results

  • Although the peak O3 concentration was frequently above the 2020 standardFootnote 6 before 2008, it has been consistently below it since then
  • Between 2002 and 2016, a decreasing trend was detected in the peak O3 concentration but the average O3 concentrations remained stable

Ozone concentrations, Canada, 2002 to 2016

Ozone concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Ozone concentrations, Canada, 2002 to 2016
Year Average concentration
(parts per billion)
Peak (4th-highest) 8-hour concentration
(parts per billion)
2002 32.8 68.2
2003 33.5 67.8
2004 31.8 59.7
2005 33.0 63.3
2006 32.7 61.7
2007 33.2 64.5
2008 32.5 60.1
2009 31.8 57.4
2010 33.1 59.6
2011 33.2 57.2
2012 33.8 60.7
2013 33.2 56.6
2014 33.1 54.4
2015 32.9 59.0
2016 32.5 56.8
2020 standard n/a 62
Annual trend No trend -0.75

Note: n/a = not applicable.

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How this indicator was calculated

Note: The national average concentration indicator is based on the annual average O3 concentrations of the daily maximum 8‑hour averages recorded at 153 monitoring stations across Canada. The national peak indicator is based on the annual 4th‑highest daily maximum 8-hour average concentrations for O3 recorded at 155 monitoring stations across Canada. The horizontal dashed line represents the 2020 Canadian Ambient Air Quality Standard. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing of the achievement status of the standard. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program and the Canadian Air and Precipitation Monitoring Network.

More information

Peak O3 concentration in 2016 was 56.8 parts per billion (ppb), which is 4% lower than in 2015. Since 2002, a decreasing trend of 0.8 ppb per year has been detected in the peak O3 concentration. The reduction in Canadian and U.S. emissions of ground-level O3 precursor gases (nitrogen oxides [NOX] and volatile organic compounds [VOCs]) is an important factor in this downward trend.

In 2016, the average O3 concentration was 32.5 ppb. No trend was detected in the average O3 concentration between 2002 and 2016.

Ozone is not directly emitted, but is formed in the lower atmosphere when precursor gases such as NOX and VOCs react in sunlight. Ground-level O3 is one of two major components of summertime smog, the other being fine particulate matter.

Average concentrations of ozone

Regional ambient levels

Key results

  • In 2016, the annual average concentrations of O3 in the air varied by region, from 26.8 ppb in British Columbia to 36.8 ppb in southern Ontario
  • From 2002 to 2016, no trends were detected

Regional average ozone concentrations, Canada, 2002 to 2016

Regional average ozone concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional average ozone concentrations, Canada, 2002 to 2016
Year Atlantic Canada average concentration
(parts per billion)
Southern Quebec average concentration
(parts per billion)
Southern Ontario average concentration
(parts per billion)
Prairies and northern Ontario average concentration
(parts per billion)
British Columbia average concentration
(parts per billion)
2002 33.7 33.6 37.8 31.8 25.7
2003 34.8 33.9 37.0 33.7 26.9
2004 33.0 32.0 35.1 32.4 25.9
2005 33.1 33.6 39.0 31.6 25.0
2006 34.5 31.0 36.3 33.6 28.4
2007 34.1 32.4 39.0 32.6 25.8
2008 32.6 31.5 37.5 33.1 26.7
2009 31.5 30.4 35.5 33.1 27.7
2010 32.0 33.1 37.8 32.8 27.5
2011 32.6 32.4 36.7 35.3 27.9
2012 32.9 33.7 38.2 33.4 29.0
2013 33.3 34.2 36.7 34.1 26.4
2014 32.8 33.2 36.7 33.1 27.9
2015 33.0 33.9 36.9 32.4 26.3
2016 31.9 33.1 37.5 31.5 26.6
Annual trend No trend No trend No trend No trend No trend
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How this indicator was calculated

Note: The regional average O3 concentration indicator is based on concentrations recorded at 17 monitoring stations in Atlantic Canada, 40 in southern Quebec, 38 in southern Ontario, 29 in the Prairies and northern Ontario region, and 28 in British Columbia. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program and the Canadian Air and Precipitation Monitoring Network.

More information

Annual average concentrations were higher in 2016 than in 2015 in southern Ontario and British Columbia. Between 2015 and 2016, the annual average concentration of O3 increased by 2% in southern Ontario and by 1% in British Columbia.

In 2016, concentrations were 3% lower than the previous year in Atlantic Canada and in the Prairies and northern Ontario region, and 2% lower in southern Quebec.

Urban areas

Key results

In 2016, among the selected urban areas

  • urban areas in Ontario had the highest O3 concentrations and Winnipeg had the lowest concentrations

Average ozone concentrations, selected Canadian urban areas, 2016

Average ozone concentrations, selected Canadian urban areas, 2016 (see data tables below for the long description)
Data tables for the long description
Average ozone concentrations, Canadian urban areas, 2002 to 2009
Urban area 2002
(parts per billion)
2003
(parts per billion)
2004
(parts per billion)
2005
(parts per billion)
2006
(parts per billion)
2007
(parts per billion)
2008
(parts per billion)
2009
(parts per billion)
Winnipeg, MB 28.0 30.5 25.5 27.0 30.5 30.0 28.0 28.0
Vancouver, BC 23.5 24.7 23.8 22.7 26.6 23.4 24.5 25.6
Halifax, NS 31.0 29.0 28.5 25.0 32.0 34.5 30.7 31.5
Saskatoon, SK 28.0 28.0 28.0 29.0 27.0 26.0 28.0 30.0
Victoria, BC 25.0 29.5 28.0 27.3 33.3 29.0 30.5 29.3
Fredericton, NB 33.8 29.3 32.8 32.9 34.7 37 34.6 32.7
Whitehorse, YT 36.0 n/a n/a 33.0 n/a n/a n/a n/a
Yellowknife, NT n/a 28.0 29.0 32.0 31.0 29.0 28.0 27.0
Edmonton, AB 32.2 32.6 32.2 31.7 33.3 33.4 33.7 34.7
Calgary, AB 29.7 30.0 28.7 27.7 29.7 30.0 32.5 33.7
Quebec City, QC 33.2 32.8 30.6 31.4 30.5 31.2 29.6 29.3
Montreal, QC 30.6 31.1 28.6 31.5 28.5 31.1 30.4 29.1
St. John's, NL 34.0 35.0 33.0 33.5 35.0 34.0 34.5 24.5
Ottawa, ON 34.0 29.0 31.0 33.0 32.0 35.0 35.0 32.0
Regina, SK 18.0 29.0 28.0 23.0 22.0 n/a 29.0 30.0
Sherbrooke, QC 39.0 39.0 35.5 36.5 33.0 34.5 34.0 33.0
Gatineau, QC 35.5 35.5 34.0 35.5 31.0 33.0 31.5 31.0
Toronto, ON 36.9 35.0 32.8 36.5 33.8 36.4 35.1 33.9
Oshawa, ON 35.0 34.0 33.0 n/a 35.0 39.0 35.0 34.0
Hamilton, ON 36.7 35.7 32.0 36.3 35.3 37.7 36.7 34.7
Charlottetown, PE n/a n/a n/a n/a n/a n/a n/a n/a
Kitchener, ON 39.0 40.0 35.0 40.0 37.0 40.0 38.0 36.0
Windsor, ON 35.5 35.5 33.0 39.5 36.5 39.5 38.0 36.0
St. Catharines – Niagara, ON 36.0 36.0 34.0 38.0 37.0 40.0 38.0 35.0
London, ON 38.0 43.0 38.5 41.5 38.5 41.5 40.5 37.0
Average ozone concentrations, Canadian urban areas, 2010 to 2016
Urban area 2010
(parts per billion)
2011
(parts per billion)
2012
(parts per billion)
2013
(parts per billion)
2014
(parts per billion)
2015
(parts per billion)
2016
(parts per billion)
Winnipeg, MB 32.5 33.5 34.0 34.0 31.0 31.0 24.5
Vancouver, BC 26.3 26.5 27.3 24.5 26.4 25.5 25.8
Halifax, NS 31.5 32.0 31.3 33.7 31.0 31.0 29.0
Saskatoon, SK 30.0 33.0 30.0 34.0 32.0 32.0 29.0
Victoria, BC 26.0 27.0 31.0 28.0 31.0 28.5 30.0
Fredericton, NB 32.7 31.1 32.0 32.8 33.2 32.3 30.2
Whitehorse, YT n/a n/a n/a n/a 31.0 33.0 30.0
Yellowknife, NT 30.0 29.0 31.0 29.0 29.0 30.0 30.0
Edmonton, AB 31.3 35.7 32.3 34.5 32.9 32.6 30.6
Calgary, AB 30.0 33.5 31.0 34.0 32.5 36.0 31.5
Quebec City, QC 31.3 30.3 31.8 33.2 31.8 32.8 32.0
Montreal, QC 31.2 30.9 31.9 32.6 31.6 32.8 32.5
St. John's, NL 33.5 33.0 34.5 32.0 33.0 35.0 33.0
Ottawa, ON 34.5 32.5 34.5 33.5 33.5 34.0 34.0
Regina, SK 29.0 34.0 28.0 26.0 33.0 34.0 34.0
Sherbrooke, QC 35.5 35.0 37.0 37.0 36.0 36.0 34.0
Gatineau, QC 33.5 33.5 36.0 34.0 35.0 35.0 35.0
Toronto, ON 35.4 34.2 36.6 34.7 34.8 34.9 36.0
Oshawa, ON 37.0 36.0 37.0 36.0 36.0 35.0 36.0
Hamilton, ON 37.3 36.0 37.0 35.5 35.3 36.3 37.3
Charlottetown, PE n/a n/a n/a n/a 34.5 38.0 n/a
Kitchener, ON 38.0 37.0 39.0 n/a 37.0 38.0 39.0
Windsor, ON 38.5 38.5 40.0 37.5 38.0 38.0 39.5
St. Catharines – Niagara, ON 38.0 38.0 39.0 38.0 38.0 38.0 40.0
London, ON 40.5 39.0 40.5 40.5 40.0 40.5 41.5

Note: n/a = not available.

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How this indicator was calculated

Note: Census metropolitan areas and census agglomerations were used to define the larger urban areas for this indicator. Only the 25 urban areas with sufficient data for the most populated municipalities in Canada and the provincial and territorial capitals are included. The Charlottetown concentration is for the year 2015. Concentrations for the years 2002 to 2016 are reported in the data table for this chart.
Source:
Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program and the Canadian Air and Precipitation Monitoring Network.

More information
Ozone is a pollutant that mostly forms in the air (secondary pollutant) as only negligible amounts are emitted directly. Ozone concentrations in selected Canadian urban areas vary from one location to another and from one year to the next. These differences are partly due to variations in local emissions of O3 precursors (mostly NOX and VOCs), variations in weather conditions that influence O3 formation, and variations in transboundary flows of pollution mainly from the United States.

Average ozone concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the average O3 concentrations at specific monitoring stations.

Average ozone concentrations by monitoring station, Canada, 2016

Average ozone concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the average concentrations of ozone in 2016 by monitoring station. Stations are categorized by the concentration of ozone measured in the air. The categories are as follows: 0 to 25 parts per billion, 25 to 30 parts per billion, 30 to 35 parts per billion, 35 to 40 parts per billion and 40 parts per billion or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

Peak concentrations of ozone

Regional ambient levels

Key results

  • Peak O3 concentrations were below the 2020 standardFootnote 5 in all regions except southern Ontario and the earliest years in southern Quebec
  • From 2002 to 2016, decreasing trends were detected in all regions, except the Prairies and northern Ontario region

Regional peak ozone concentrations, Canada, 2002 to 2016

Regional peak ozone concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional peak ozone concentrations, Canada, 2002 to 2016
Year Atlantic Canada peak (4th-highest) 8-hour concentration
(parts per billion)
Southern Quebec peak (4th-highest) 8-hour concentration
(parts per billion)
Southern Ontario peak (4th-highest) 8-hour concentration
(parts per billion)
Prairies and northern Ontario peak (4th-highest) 8-hour concentration
(parts per billion)
British Columbia peak (4th-highest) 8-hour concentration
(parts per billion)
2002 59.5 72.8 88.0 58.6 49.8
2003 59.6 71.4 84.5 60.2 51.9
2004 55.3 60.6 69.1 54.2 55.2
2005 53.1 67.3 81.3 54.2 49.2
2006 58.1 61.4 73.8 57.6 52.7
2007 56.9 67.2 80.8 56.6 50.0
2008 53.6 59.3 72.0 57.8 51.8
2009 54.5 55.5 66.8 56.2 51.0
2010 51.5 60.6 71.1 57.9 49.7
2011 51.1 55.6 67.4 59.3 47.4
2012 50.2 61.3 76.1 56.0 50.2
2013 50.6 57.5 65.0 56.9 47.3
2014 48.4 53.8 62.9 53.4 48.6
2015 51.6 59.9 66.2 60.9 50.8
2016 47.8 58.0 67.9 58.4 44.8
Annual trend -0.8 -1.0 -1.4 No trend -0.4
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How this indicator was calculated

Note: The regional peak O3 indicator is based on concentrations recorded at 18 monitoring stations in Atlantic Canada, 40 in southern Quebec, 38 in southern Ontario, 29 in the Prairies and northern Ontario region, and 29 in British Columbia. The horizontal dashed line represents the 8-hour standard of the 2020 Canadian Ambient Air Quality Standards. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing the achievement status of the standard. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program and the Canadian Air and Precipitation Monitoring Network.

More information

In 2016, the highest annual peak concentration of O3 was recorded in southern Ontario, at 67.9 ppb, which is 3% higher than in 2015. British Columbia recorded the lowest concentration level, at 44.8 ppb, which is 12% lower than in 2015. Annual peak concentrations of O3 were 3% to 7% lower in the other regions compared to 2015.

Over the 2002 to 2016 period, peak O3 concentrations were below the 2020 standard in the Prairies and northern Ontario region, British Columbia and Atlantic Canada. Peak O3 concentrations in southern Quebec were higher than the standard for most of the years before 2008. Peak concentrations in southern Ontario remained above the standard for all years.

From 2002 to 2016, decreasing trends of 0.8 ppb, 1.0 ppb, 1.4 ppb and 0.4 ppb per year were detected in Atlantic Canada, southern Quebec, southern Ontario and British Columbia, respectively. No trend was detected in the Prairies and northern Ontario region.

Urban areas

Key results

In 2016, among the selected urban areas

  • Most of the highest concentrations of peak O3 in Canada were reported in Ontario and the lowest concentration was recorded in Vancouver

Peak ozone concentrations, selected Canadian urban areas, 2016

Peak ozone concentrations, selected Canadian urban areas, 2016 (see data tables below for the long description)
Data tables for the long description
Peak ozone concentrations, Canadian urban areas, 2002 to 2009
Urban area 2002
(parts per billion)
2003
(parts per billion)
2004
(parts per billion)
2005
(parts per billion)
2006
(parts per billion)
2007
(parts per billion)
2008
(parts per billion)
2009
(parts per billion)
Vancouver, BC 46.0 47.6 53.8 46.1 49.8 46.8 48.9 47.5
Winnipeg, MB 52.9 57.8 43.2 52.0 52.0 51.7 50.6 49.8
Yellowknife, NT 40.3 46.1 43.1 53.3 52.9 46.4 48.8 42.0
Halifax, NS 55.1 50.0 49.8 42.9 55.4 52.3 49.9 55.1
Fredericton, NB 59.9 60 61.6 52.6 64.6 63.8 58.3 54.1
St. John's, NL 55.8 52.4 50.5 47.0 49.0 51.2 53.0 46.9
Victoria, BC 46.4 48.7 49.2 49.2 53.5 53.9 51.7 50.6
Whitehorse, YT 55.8 n/a n/a 47.5 n/a n/a 50.8 n/a
Quebec City, QC 72.2 66.9 53.6 60.3 59.3 66.3 54.3 53.4
Saskatoon, SK 51.3 47.3 53.5 50.6 44.8 44.6 45.9 51.6
Charlottetown, PE n/a n/a n/a n/a n/a n/a n/a n/a
Edmonton, AB 69.0 61.0 57.5 54.7 61.5 61.6 62.0 62.8
Montreal, QC 72.6 73.1 58.8 67.5 60.0 66.9 58.5 55.5
Regina, SK 32.6 66.1 48.5 40.5 38.9 n/a 52.5 51.1
Ottawa, ON 75.7 67.1 55.0 72.4 67.3 70.3 66.7 59.0
Calgary, AB 58.3 56.3 53.0 48.6 54.2 55.4 53.7 58.1
Sherbrooke, QC 77.5 74.1 66.0 71.0 59.7 67.4 64.2 58.1
Gatineau, QC 75.8 79.8 67.7 78.1 65.4 69.5 66.5 56.5
Toronto, ON 86.2 85.0 68.0 79.5 72.6 80.0 71.0 67.9
St. Catharines – Niagara, ON 91.0 91.5 68.6 82.6 75.0 84.0 70.0 64.5
Oshawa, ON 83.4 82.9 60.8 84.5 70.0 86.4 64.7 63.4
Hamilton, ON 87.9 86.0 67.4 79.7 73.6 78.0 71.7 66.6
Kitchener, ON 93.5 87.4 69.5 79.4 73.1 77.4 70.9 65.1
London, ON 101.1 94.4 73.8 83.8 78.9 83.2 78.1 67.9
Windsor, ON 95.7 92.0 73.0 91.1 79.7 92.4 77.7 69.0
Peak ozone concentrations, Canadian urban areas, 2010 to 2016
Urban area 2010
(parts per billion)
2011
(parts per billion)
2012
(parts per billion)
2013
(parts per billion)
2014
(parts per billion)
2015
(parts per billion)
2016
(parts per billion)
Vancouver, BC 48.0 45.2 46.0 45.1 46.0 47.6 42.6
Winnipeg, MB 63.9 53.0 58.7 55.7 54.3 60.1 44.3
Yellowknife, NT 44.3 48.0 50.6 49.5 44.9 44.4 45.0
Halifax, NS 57.6 57.1 50.6 48.9 51.3 46.3 45.4
Fredericton, NB 50.4 48.1 50.1 50.6 48.4 55.3 45.4
St. John's, NL 47.0 51.9 49.8 50.1 45.6 54.3 46.0
Victoria, BC 43.4 44.5 48.9 47.2 47.8 46.6 46.2
Whitehorse, YT n/a n/a 49.6 n/a 53.1 55.1 47.1
Quebec City, QC 58.3 51.4 55.9 56.3 51.7 56.1 53.2
Saskatoon, SK 56.0 58.5 48.0 54.6 50.0 58.1 54.3
Charlottetown, PE n/a n/a n/a n/a 52.1 56.6 n/a
Edmonton, AB 59.9 61.8 54.4 60.2 53.4 61.6 57.8
Montreal, QC 60.8 55.9 62.3 56.3 52.5 61.0 58.2
Regina, SK 53.8 59.4 47.6 50.9 54.6 62.0 59.1
Ottawa, ON 61.9 54.6 65.2 58.5 53.0 61.9 59.5
Calgary, AB 53.8 55.3 53.5 59.2 52.5 62.7 59.8
Sherbrooke, QC 60.8 58.2 60.5 59.3 56.1 60.7 60.2
Gatineau, QC 63.2 55.0 68.1 61.0 57.4 64.0 62.2
Toronto, ON 71.0 65.2 74.2 65.1 61.7 65.9 67.0
St. Catharines – Niagara, ON 67.9 68.3 73.3 65.0 61.8 66.4 67.3
Oshawa, ON 75.5 65.5 71.1 63.1 60.6 62.8 67.8
Hamilton, ON 69.5 66.7 70.7 64.9 61.4 63.4 68.5
Kitchener, ON 66.9 65.6 73.5 n/a 64.9 65.1 69.3
London, ON 75.1 72.7 78.9 73.3 68.8 69.0 71.3
Windsor, ON 73.0 80.6 82.7 66.7 69.1 69.5 73.8

Note: n/a = not available.

Download data file (Excel/CSV; 3.44 kB)

How this indicator was calculated

Note: Census metropolitan areas and census agglomerations were used to define the larger urban areas for this indicator. Only the 25 urban areas with sufficient data for the most populated municipalities in Canada and the provincial and territorial capitals are included. The Charlottetown concentration is for the year 2015. Concentrations for the years 2002 to 2016 are reported in the data table for this chart.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program and the Canadian Air and Precipitation Monitoring Network.

More information
Ozone is a secondary pollutant that mostly forms in the air through the chemical interactions of precursors. Only negligible amounts of O3 are emitted directly. Ozone concentrations in selected Canadian urban areas vary from one location to another and from one year to the next. These differences are partly due to variations in local emissions of O3 precursors (mostly NOX and VOCs), variations in weather conditions that influence O3 formation, and variations in transboundary flows of pollution mainly from the United States.

Peak ozone concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the peak O3 concentrations at specific monitoring stations.

Peak ozone concentrations by monitoring station, Canada, 2016

Peak ozone concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the peak concentrations of ozone in 2016 by monitoring station. Stations are categorized by the concentration of ozone measured in the air. The categories are as follows: 0 to 45 parts per billion, 45 to 50 parts per billion, 50 to 55 parts per billion, 55 to 62 parts per billion and 62 parts per billion or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program

Nitrogen dioxide

Nitrogen dioxide

Nitrogen dioxide (NO2) plays an important role in the formation of ozone in the atmosphere. It is also a precursor to fine particulate matter, and contributes to acid deposition and eutrophication. Nitrogen dioxide has adverse health effects: it can irritate the lungs, decrease lung function and increase susceptibility to allergens for people with asthma.

Average concentrations of nitrogen dioxide
Peak concentrations of nitrogen dioxide

Key results

Between 2002 and 2016

  • the average and peak concentrations of NO2Footnote 7,Footnote 8 were consistently below the standards
  • a decreasing trend in both the average and peak concentrations of NO2 was detected.  

Nitrogen dioxide concentrations, Canada, 2002 to 2016

Nitrogen dioxide concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Nitrogen dioxide concentrations, Canada, 2002 to 2016
Year Average concentration
(parts per billion)
Peak (98th percentile) 1-hour concentration
(parts per billion)
2002 13.7 51.6
2003 13.9 50.4
2004 12.2 49.5
2005 12.0 49.6
2006 11.2 47.4
2007 11.2 45.8
2008 10.9 44.9
2009 10.2 44.1
2010 9.5 43.4
2011 9.5 42.2
2012 8.7 40.5
2013 8.7 39.7
2014 8.7 39.5
2015 8.4 39.8
2016 7.8 38.8
2020 standard 17.0 60.0
Annual trend -0.41 -1.00
Download data file (Excel/CSV; 1.59 kB)

How this indicator was calculated

Note: The national average NO2 concentration indicator is based on the annual average concentrations of the hourly averages recorded at 101 monitoring stations across Canada while the national peak indicator is based on the annual 98th percentile of the daily maximum 1-hour average concentrations for NO2 recorded at 89 monitoring stations across Canada. The horizontal dashed lines represent the 2020 Canadian Ambient Air Quality Standards. The Canadian Ambient Air Quality Standards are provided for illustrative purposes only and not for assessing the achievement status of the standards. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the national average concentration of NO2 was 7.8 parts per billion (ppb), which is 7% lower than in 2015. The annual peak NO2 concentration in 2016 was 38.8 ppb, which is 3% lower than in 2015.

Since 2002, a decreasing trend of 0.4 ppb per year has been detected in the average NO2 concentration. A trend was also detected in the peak NO2 concentrations: a decrease of 1.0 ppb per year. These trends are mainly attributable to the federal government introducing progressively more stringent emissions standards for cars and trucks.

Nitrogen dioxide (NO2) belongs to a group of substances called nitrogen oxides (NOX).Footnote 9 Nitrogen oxides are emitted into the atmosphere from high-temperature combustion processes such as vehicle engines, power plants and industrial processes. The main sources of nitrogen oxides in Canada are on-road and off-road vehicles, the oil and gas industry, and the use of fuel for electricity generation and heating.

Average concentrations of nitrogen dioxide

Regional ambient levels

Key results

  • All regions across Canada had NO2 concentrations that were consistently below the 2020 standard,Footnote 5 except southern Ontario in 2002 and 2003
  • Between 2002 and 2016, a decreasing trend in the average concentration of NO2 was detected in all regions

Regional average nitrogen dioxide concentrations, Canada, 2002 to 2016

Regional average nitrogen dioxide concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional average nitrogen dioxide concentrations, Canada, 2002 to 2016
Year Atlantic Canada average concentration
(parts per billion)
Southern Quebec average concentration
(parts per billion)
Southern Ontario average concentration
(parts per billion)
Prairies and northern Ontario average concentration
(parts per billion)
British Columbia average concentration
(parts per billion)
2002 6.9 14.9 18.5 10.6 14.3
2003 7.0 16.2 17.8 10.9 14.0
2004 5.5 14.3 15.2 9.2 13.6
2005 5.1 14.0 15.6 9.1 13.0
2006 3.3 12.0 13.3 9.0 13.2
2007 4.0 12.0 12.7 9.4 12.3
2008 4.5 12.2 12.3 9.7 11.8
2009 3.4 11.0 11.2 8.9 12.1
2010 3.7 10.6 10.5 8.6 10.8
2011 4.0 11.6 10.5 8.0 10.4
2012 3.4 9.2 9.4 7.4 10.5
2013 4.3 9.1 9.3 8.0 10.2
2014 3.8 8.6 9.6 7.8 10.5
2015 3.6 8.5 9.3 7.5 10.1
2016 3.1 8.4 8.7 6.8 9.2
Annual trend -0.19 -0.52 -0.66 -0.23 -0.35
Download data file (Excel/CSV; 1.87 kB)

How this indicator was calculated

Note: The regional average NO2 indicator is based on the concentrations recorded at 7 monitoring stations in Atlantic Canada, 15 in southern Quebec, 25 in southern Ontario, 27 in the Prairies and northern Ontario region, and 26 in British Columbia. The horizontal dashed line represents the 2020 Canadian Ambient Air Quality Standard. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing the achievement status of the standards. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the annual average concentrations of NO2 varied by region, from 3.1 ppb in Atlantic Canada to 9.2 ppb in British Columbia. In Atlantic Canada and British Columbia, the annual average concentrations of NO2 in 2016 were 15% and 9% lower than in 2015. The concentrations in the Prairies and northern Ontario region, southern Ontario and southern Quebec were, respectively, 10%, 6% and 0.2% lower in 2016 than in 2015.

Between 2002 and 2016, southern Ontario, southern Quebec and British Columbia experienced the most rapid decreases in average NO2 concentrations. Decreasing trends of 0.7 ppb, 0.5 ppb and 0.4 ppb per year were detected for southern Ontario, southern Quebec and British Columbia, respectively. A decreasing trend of 0.2 ppb per year was also observed for Atlantic Canada and the Prairies and northern Ontario region.

Urban areas

Key results

In 2016, among the selected urban areas

  • concentrations of NO2 were the highest in Calgary, Toronto, Windsor, Vancouver and Hamilton, while Charlottetown, Yellowknife and Fredericton had the lowest concentrations

Average nitrogen dioxide concentrations, selected Canadian urban areas, 2016

Average nitrogen dioxide concentrations, selected Canadian urban areas, 2016 (see data tables below for the long description)
Data tables for the long description
Average nitrogen dioxide concentrations, Canadian urban areas, 2002 to 2009
Urban area 2002
(parts per billion)
2003
(parts per billion)
2004
(parts per billion)
2005
(parts per billion)
2006
(parts per billion)
2007
(parts per billion)
2008
(parts per billion)
2009
(parts per billion)
Charlottetown, PE n/a n/a n/a n/a n/a n/a n/a n/a
Yellowknife, NT n/a n/a 4.5 3.9 3.9 2.8 1.9 2.1
Fredericton, NB 3.9 4.8 4.1 n/a 3.1 3.6 3.3 n/a
St. John's, NL n/a 5.6 4.6 4.7 4.0 n/a 4.7 2.8
London, ON n/a n/a 13.7 14.1 12.3 11.7 10.8 9.0
Halifax, NS n/a n/a n/a n/a 15.7 n/a 8.7 n/a
Whitehorse, YT 0.7 0.2 n/a 3.6 n/a n/a n/a n/a
Gatineau, QC 11.1 11.3 10.6 10.0 8.2 7.9 8.6 7.9
Kitchener, ON n/a n/a 13.1 12.9 10.8 9.7 9.0 8.6
Ottawa, ON 27.1 17.9 16.8 9.8 8.6 8.3 9.8 7.6
Oshawa, ON 17.2 16.2 14.2 n/a 8.9 8.1 n/a 7.4
Quebec City, QC 14.1 15.4 13.5 12.6 n/a 12.4 13.2 11.2
St. Catharines – Niagara, ON n/a n/a n/a n/a 11.7 12.0 10.4 9.9
Victoria, BC 10.4 8.4 n/a 8.2 5.4 6.3 6.5 10.6
Regina, SK 13.9 13.9 11.6 12.1 14.7 12.0 10.8 10.1
Edmonton, AB 17.2 16.9 11.8 10.8 10.1 9.6 10.2 10.5
Winnipeg, MB 12.1 12.0 11.0 9.9 10.1 10.4 11.7 11.6
Barrie, ON 14.4 14.8 13.3 13.8 12.6 11.4 10.8 9.9
Montreal, QC 16.1 17.7 15.8 15.3 13.0 13.1 13.4 11.8
Saskatoon, SK 11.7 11.7 11.8 9.9 10.5 n/a 8.5 10.3
Hamilton, ON 19.4 17.9 16.1 18.3 16.6 15.0 12.9 12.0
Vancouver, BC 16.2 16.0 14.9 15.3 14.4 13.8 13.3 13.7
Windsor, ON 19.4 23.3 18.0 17.0 16.5 16.7 15.7 13.8
Toronto, ON 20.0 21.1 18.5 19.2 17.1 16.6 15.4 15.2
Calgary, AB 22.4 23.5 20.7 20.1 19.7 19.0 21.5 18.8
Average nitrogen dioxide concentrations, Canadian urban areas, 2010 to 2016
Urban area 2010
(parts per billion)
2011
(parts per billion)
2012
(parts per billion)
2013
(parts per billion)
2014
(parts per billion)
2015
(parts per billion)
2016
(parts per billion)
Charlottetown, PE n/a n/a n/a n/a 1.1 1.1 n/a
Yellowknife, NT 4.7 3.0 2.2 3.2 2.8 3.1 1.9
Fredericton, NB 2.8 3.4 2.4 3.4 3.2 3.2 2.4
St. John's, NL 4.3 4.0 3.8 4.5 3.9 3.2 3.5
London, ON 8.8 8.3 6.3 6.4 6.9 4.8 4.1
Halifax, NS 12.5 7.0 6.5 6.0 1.7 5.8 5.0
Whitehorse, YT n/a n/a 5.9 5.2 n/a 5.3 n/a
Gatineau, QC 6.6 6.9 6.1 6.3 5.6 5.6 5.9
Kitchener, ON 7.7 7.7 7.1 6.7 7.0 6.8 6.2
Ottawa, ON 6.8 7.3 7.2 7.3 6.7 6.6 6.3
Oshawa, ON 7.2 7.0 5.6 5.9 6.8 6.6 6.3
Quebec City, QC 7.9 8.4 9.1 8.8 9.1 8.7 6.6
St. Catharines – Niagara, ON 9.1 8.5 8.0 7.7 7.3 7.3 6.6
Victoria, BC 9.9 6.8 7.0 7.2 6.7 8.6 6.7
Regina, SK 10.9 9.4 9.3 9.3 11.0 n/a 7.3
Edmonton, AB 10.2 8.2 7.6 8.5 8.0 8.3 7.8
Winnipeg, MB 8.1 9.7 7.8 7.6 5.9 7.0 8.0
Barrie, ON 8.7 8.6 8.1 7.8 8.1 7.4 8.1
Montreal, QC 11.1 11.7 10.1 9.9 9.3 8.5 8.9
Saskatoon, SK 11.1 11.4 10.5 11.1 9.7 8.2 8.9
Hamilton, ON 11.3 12.1 10.9 11.3 11.3 11.0 10.5
Vancouver, BC 11.9 11.5 11.6 11.6 11.5 11.1 10.6
Windsor, ON 15.1 13.7 12.3 12.0 12.9 11.8 11.0
Toronto, ON 13.7 13.7 12.2 11.9 12.3 11.9 11.2
Calgary, AB 17.6 17.3 12.1 13.7 15.0 15.4 12.2

Note: n/a = not available.

Download data file (Excel/CSV; 3.11 kB)

How this indicator was calculated

Note: Census metropolitan areas and census agglomerations were used to define the larger urban areas for this indicator. Only the 25 urban areas with sufficient data for the most populated municipalities in Canada and the provincial and territorial capitals are included. The Charlottetown and Whitehorse concentrations are for the year 2015. Concentrations for the years 2002 to 2016 are reported in the data table for this chart.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information
Nitrogen dioxide concentrations in selected Canadian urban areas vary from one location to another. Urban areas in proximity to important sources of NO2 such as large road networks and highways may explain the differences between cities.

Average nitrogen dioxide concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the NO2 concentrations at specific monitoring stations.

Average nitrogen dioxide concentrations by monitoring station, Canada, 2016

Average nitrogen dioxide concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the average concentrations of nitrogen dioxide in 2016 by monitoring station. Stations are categorized by the concentration of nitrogen dioxide measured in the air. The categories are as follows: 0 to 4 parts per billion, 4 to 8 parts per billion, 8 to 12 parts per billion, 12 to 17 parts per billion and 17 parts per billion or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program

Peak concentrations of nitrogen dioxide

Regional ambient levels

Key results

  • All regions across Canada had peak concentrations of NO2 that were consistently below the 2020 standard,Footnote 5 except southern Ontario in the first 4 years
  • Between 2002 and 2016, a decreasing trend in the peak concentration of NO2 was detected in all regions

Regional peak nitrogen dioxide concentrations, Canada, 2002 to 2016

Regional peak nitrogen dioxide concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional peak nitrogen dioxide concentrations, Canada, 2002 to 2016
Year Atlantic Canada peak (98th percentile)
1-hour
concentration
(parts per billion)
Southern Quebec peak (98th percentile)
1-hour
concentration
(parts per billion)
Southern Ontario peak (98th percentile)
1-hour
concentration
(parts per billion)
Prairies and northern Ontario peak (98th percentile)
1-hour
concentration
(parts per billion)
British Columbia peak (98th percentile)
1-hour
concentration
(parts per billion)
2002 49.5 59.2 61.9 44.3 45.4
2003 42.4 59.3 62.4 45.0 44.2
2004 38.8 56.5 62.8 44.0 43.7
2005 38.7 57.6 61.6 43.9 42.7
2006 35.2 52.6 57.8 43.1 42.9
2007 32.8 50.9 54.0 42.7 40.8
2008 33.2 49.5 51.5 42.9 40.4
2009 32.5 50.3 49.8 41.2 39.6
2010 33.5 48.1 47.7 43.2 38.7
2011 31.2 48.4 47.0 43.4 36.3
2012 28.8 45.5 44.5 42.0 35.1
2013 29.4 42.6 43.4 41.7 35.4
2014 30.5 41.3 43.8 40.8 35.9
2015 30.8 42.2 45.4 40.1 35.3
2016 29.3 42.1 45.1 37.5 35.2
Annual trend -0.91 -0.37 -1.66 -0.34 -0.78
Download data file (Excel/CSV; 2.02 kB)

How this indicator was calculated

Note: The regional peak NO2 indicator is based on the concentrations recorded at 6 monitoring stations in Atlantic Canada, 15 in southern Quebec, 22 in southern Ontario, 21 in the Prairies and northern Ontario region, and 25 in British Columbia. The horizontal dashed line represents the 2020 Canadian Ambient Air Quality Standard. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing the achievement status of the standards. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the annual peak concentrations of NO2 varied by region, from 29.3 ppb in Atlantic Canada to 45.1 ppb in southern Ontario. In the Prairies and northern Ontario region and Atlantic Canada, respectively, the annual peak concentrations of NO2 were 6.4% and 5% lower in 2016 than in 2015. Peak concentrations were less than 1% lower in 2016 than in 2015 in British Columbia, southern Ontario and southern Quebec.

Between 2002 and 2016, southern Ontario, southern Quebec and Atlantic Canada experienced the most rapid decreases in peak NO2 concentrations. Decreasing trends of 1.7 ppb, 1.4 ppb and 0.9 ppb per year were detected for southern Ontario, southern Quebec and Atlantic Canada, respectively. Decreasing trends of 0.8 ppb and 0.3 ppb per year were observed for British Columbia and for the Prairies and northern Ontario region, respectively.

Urban areas

Key results

In 2016, among the selected urban areas

  • the highest peak concentrations of NO2 were recorded in Calgary, Regina and Toronto, and the lowest concentrations were recorded in Charlottetown, Halifax, Yellowknife and London

Peak nitrogen dioxide concentrations, selected Canadian urban areas, 2016

Peak nitrogen dioxide concentrations, selected Canadian urban areas, 2016 (see data tables below for the long description)
Data tables for the long description
Peak nitrogen dioxide concentrations, Canadian urban areas, 2002 to 2009
Urban area 2002
(parts per billion)
2003
(parts per billion)
2004
(parts per billion)
2005
(parts per billion)
2006
(parts per billion)
2007
(parts per billion)
2008
(parts per billion)
2009
(parts per billion)
Charlottetown, PE n/a n/a n/a n/a n/a n/a n/a n/a
Halifax, NS 67.0 n/a n/a n/a 64.0 64.0 n/a n/a
Yellowknife, NT n/a n/a n/a 35.0 33.0 30.0 27.0 24.0
London, ON 73.0 n/a n/a 53.0 52.0 51.0 48.0 46.0
St. John's, NL 47.0 46.0 33.0 32.5 31.0 27.0 30.0 29.0
Victoria, BC 38.0 41.0 42.0 37.0 30.0 n/a 23.5 41.0
Fredericton, NB n/a 35.0 35.0 38.0 34.0 32.0 34.0 37.0
Oshawa, ON 63.0 62.0 59.0 60.0 n/a 39.0 n/a 38.0
Vancouver, BC 47.8 47.3 46.9 46.5 45.6 44.5 43.0 42.8
Whitehorse, YT n/a 5.0 5.0 15.0 n/a n/a n/a n/a
St. Catharines – Niagara, ON 67.0 n/a n/a n/a n/a 49.0 48.0 47.0
Gatineau, QC 48.0 49.0 48.0 49.0 47.0 44.0 43.0 43.0
Edmonton, AB 58.8 59.0 58.0 54.7 45.5 46.8 47.9 48.6
Kitchener, ON 48.0 59.0 66.0 64.0 58.0 52.0 47.0 46.0
Ottawa, ON 76.0 85.5 82.0 55.0 46.0 45.0 46.5 46.0
Winnipeg, MB 51.0 50.0 48.0 47.5 46.0 49.0 49.5 63.0
Montreal, QC 63.5 62.8 58.8 60.1 54.5 52.7 51.3 52.3
Quebec City, QC 59.0 58.0 58.0 59.0 57.0 55.0 57.0 56.0
Saskatoon, SK n/a 49.0 49.0 49.0 47.0 n/a 40.0 43.0
Hamilton, ON 60.0 63.0 61.0 60.0 58.0 58.0 53.7 51.3
Windsor, ON 64.0 66.0 65.5 63.0 57.5 54.5 53.0 52.0
Barrie, ON n/a 64.0 62.0 67.0 61.0 59.0 55.0 52.0
Toronto, ON 66.3 65.8 67.1 66.3 63.6 62.1 58.9 56.3
Regina, SK 55.0 54.0 51.0 51.0 59.0 59.0 59.0 52.0
Calgary, AB 69.3 70.7 71.3 68.7 67.0 64.0 65.3 62.5
Peak nitrogen dioxide concentrations, Canadian urban areas, 2010 to 2016
Urban area 2010
(parts per billion)
2011
(parts per billion)
2012
(parts per billion)
2013
(parts per billion)
2014
(parts per billion)
2015
(parts per billion)
2016
(parts per billion)
Charlottetown, PE n/a n/a n/a n/a n/a 12.5 n/a
Halifax, NS n/a 45.0 29.0 27.5 27.0 28.0 26.0
Yellowknife, NT 24.0 25.0 28.0 30.0 28.0 28.0 27.0
London, ON 45.0 45.0 39.0 n/a 37.0 38.0 28.0
St. John's, NL 30.0 30.0 30.0 30.5 32.5 32.5 30.5
Victoria, BC 40.0 38.0 30.5 31.0 32.5 32.0 32.0
Fredericton, NB 37.0 34.0 33.0 34.0 33.0 35.0 32.0
Oshawa, ON 36.0 38.0 35.0 33.0 32.0 36.0 37.0
Vancouver, BC 41.0 38.9 37.4 37.6 38.4 37.6 37.7
Whitehorse, YT n/a n/a n/a 40.0 40.0 38.0 n/a
St. Catharines – Niagara, ON 43.0 40.0 38.0 38.0 39.0 40.0 39.0
Gatineau, QC 42.0 40.0 36.0 36.0 36.0 37.0 39.0
Edmonton, AB 52.5 45.2 43.4 41.8 41.8 42.2 39.5
Kitchener, ON 46.0 45.0 41.0 40.0 40.0 43.0 41.0
Ottawa, ON 45.0 41.5 40.5 41.5 42.0 43.0 42.0
Winnipeg, MB 55.0 54.0 48.0 48.0 43.5 41.5 43.0
Montreal, QC 49.8 48.8 46.3 44.6 43.2 44.4 43.5
Quebec City, QC 53.0 43.3 47.0 46.0 43.0 43.0 44.0
Saskatoon, SK 46.0 52.0 51.0 50.0 48.0 45.0 45.0
Hamilton, ON 48.7 46.7 45.0 45.0 45.3 46.5 45.3
Windsor, ON 53.5 54.5 53.0 49.5 48.5 48.5 46.0
Barrie, ON 50.0 46.0 43.0 41.0 43.0 45.0 48.0
Toronto, ON 53.2 52.2 50.1 48.8 50.0 51.0 50.7
Regina, SK 54.0 51.0 48.0 45.0 n/a n/a 51.0
Calgary, AB 67.0 67.0 59.5 58.0 56.5 56.5 52.0

Note: n/a = not available.

Download data file (Excel/CSV; 2.89 kB)

How this indicator was calculated

Note: Census metropolitan areas and census agglomerations were used to define the larger urban areas for this indicator. Only the 25 urban areas with sufficient data for the most populated municipalities in Canada and the provincial and territorial capitals are included. The Charlottetown and Whitehorse concentrations are for the year 2015. Concentrations for the years 2002 to 2016 are reported in the data table for this chart.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information
Nitrogen dioxide concentrations in selected Canadian urban areas vary from one location to another. Urban areas in proximity to important sources of NO2 such as large roads network and highways may explain the differences between cities.

Peak nitrogen dioxide concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the peak NO2 concentrations at specific monitoring stations.

Peak nitrogen dioxide concentrations by monitoring station, Canada, 2016

Peak nitrogen dioxide concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the peak concentrations of nitrogen dioxide in 2016 by monitoring station. Stations are categorized by the concentration of nitrogen dioxide measured in the air. The categories are as follows: 0 to 30 parts per billion, 30 to 40 parts per billion, 40 to 50 parts per billion, 50 to 60 parts per billion and 60 parts per billion or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

Sulphur dioxide

Sulphur dioxide

Sulphur dioxide (SO2) is emitted when a fuel or raw material containing sulphur is burned or used in industrial processes such as metal ore smelting. Sulphur dioxide emissions contribute to acid deposition and are a major precursor to fine particulate matter. High concentrations of SO2 can adversely affect the respiratory systems of humans and animals and can damage vegetation and materials.

Average concentrations of sulphur dioxide
Peak concentrations of sulphur dioxide

Key results

Between 2002 and 2016

  • the average and peak concentrations of SO2 were consistently below the standardsFootnote 10 
  • a decreasing trend in both the average and peak concentrations of SO2 was detected

Sulphur dioxide concentrations, Canada, 2002 to 2016

Sulphur dioxide concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Sulphur dioxide concentrations, Canada, 2002 to 2016
Year Average concentration
(parts per billion)
Peak (99th percentile) 1-hour concentration
(parts per billion)
2002 2.8 60.8
2003 2.6 59.8
2004 2.3 60.2
2005 2.2 63.1
2006 2.1 58.8
2007 2.2 56.7
2008 1.9 56.0
2009 1.7 49.4
2010 1.5 50.5
2011 1.5 36.5
2012 1.5 37.6
2013 1.3 36.3
2014 1.3 33.6
2015 1.1 31.8
2016 1.0 29.4
2020 standard 5.0 70.0
Annual trend -0.11 -2.51
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How this indicator was calculated

Note: The national average SO2 concentration indicator is based on the annual average concentrations of the hourly averages recorded at 65 monitoring stations across Canada while the national peak indicator is based on the annual 99th percentile of the daily maximum 1-hour average concentrations for SO2 recorded at 68 monitoring stations across Canada. The horizontal dashed lines represent the 2020 Canadian Ambient Air Quality Standards. The Canadian Ambient Air Quality Standards are provided for illustrative purposes only and not for assessing the achievement status of the standards. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the national average concentration of SO2 was 1.0 part per billion (ppb), which is 9% lower than in 2015. The annual peak SO2 concentration in 2016 was 29.4 ppb, which is 7% lower than in 2015.

Since 2002, a decreasing trend of 0.1 ppb per year has been detected in the average SO2 concentration. A trend was also detected for the peak SO2 concentrations, specifically a decrease of 2.5 ppb per year. These trends are mainly attributable to reductions in sulphur oxide (SOX) emissions in Canada and the United States resulting from efforts to curb acid rain and ambient particulate matter. Efforts also included the implementation of federal regulations related to sulphur content in fuels.

The main sources of sulphur oxide emissions in Canada are the combustion of fuel for electricity generation and heating, processes in the non-ferrous mining and smelting industry, and the oil and gas industry.

Average concentrations of sulphur dioxide

Regional ambient levels

Key results

  • Since 2004, SO2 concentrations in all regions across Canada have consistently been below the 2020 standardFootnote 5 
  • Between 2002 and 2016, a decreasing trend in the average concentration of SO2 was detected in all regions

Regional average sulphur dioxide concentrations, Canada, 2002 to 2016

Regional average sulphur dioxide concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional average sulphur dioxide concentrations, Canada, 2002 to 2016
Year Atlantic Canada average concentration
(parts per billion)
Southern Quebec average concentration
(parts per billion)
Southern Ontario average concentration
(parts per billion)
Prairies and northern Ontario average concentration
(parts per billion)
British Columbia average concentration
(parts per billion)
2002 5.7 4.3 6.0 1.7 2.0
2003 4.2 4.6 5.2 1.6 1.9
2004 3.5 4.3 3.6 1.6 1.8
2005 3.3 4.3 3.9 1.5 1.8
2006 2.6 3.6 3.8 1.4 2.0
2007 3.4 2.7 3.6 1.7 1.7
2008 1.3 2.8 3.3 1.5 1.9
2009 1.1 2.0 2.4 1.3 1.9
2010 0.7 1.8 2.2 1.2 1.6
2011 1.2 1.6 3.0 0.9 1.6
2012 1.5 2.1 2.4 0.9 1.6
2013 1.1 1.8 2.2 0.9 1.4
2014 0.9 1.7 2.3 1.0 1.2
2015 0.7 1.5 2.0 1.0 1.0
2016 0.6 1.7 1.5 0.8 1.0
Annual trend -0.38 -0.26 -0.28 -0.08 -0.05
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How this indicator was calculated

Note: The regional average SO2 indicator is based on the concentrations recorded at 5 monitoring stations in Atlantic Canada, 7 in southern Quebec, 7 in southern Ontario, 24 in the Prairies and northern Ontario region, and 21 in British Columbia. The horizontal dashed line represents the 2020 Canadian Ambient Air Quality Standard. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing the achievement status of the standards. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source:
Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the annual average concentrations of SO2 varied by region, from 0.6 ppb in Atlantic Canada to 1.7 ppb in southern Quebec. In southern Ontario and in Atlantic Canada, respectively, the annual average concentration of SO2 in 2016 was 27% and 14% lower than in 2015. Southern Quebec and British Columbia recorded concentrations that were 17% and 1% higher, respectively, than in 2015. The Prairies and northern Ontario region reported levels 19% lower than in 2015.

Between 2002 and 2016, Atlantic Canada, southern Quebec and southern Ontario experienced the most rapid decreases in average SO2 concentrations. Decreasing trends of 0.3 ppb, 0.2 ppb and 0.2 ppb per year were detected for Atlantic Canada, southern Quebec and southern Ontario, respectively. A decreasing trend of 0.1 ppb per year was observed for the Prairies and northern Ontario region and for British Columbia.

Average sulphur dioxide concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the SO2 concentrations at specific monitoring stations.

Average sulphur dioxide concentrations by monitoring station, Canada, 2016

Average sulphur dioxide concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the average concentrations of sulphur dioxide in 2016 by monitoring station. Stations are categorized by the concentration of sulphur dioxide measured in the air. The categories are as follows: 0 to 0.5 parts per billion, 0.5 to 1 parts per billion, 1 to 2 parts per billion, 2 to 5 parts per billion and 5 parts per billion or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

Peak concentrations of sulphur dioxide

Regional ambient levels

Key results

  • Since 2009, the peak SO2 concentrations were below the 2020 standardFootnote 5 in all regions
  • From 2002 to 2016, decreasing trends were detected in all regions

Regional peak sulphur dioxide concentrations, Canada, 2002 to 2016

Regional peak sulphur dioxide concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional peak sulphur oxides concentrations, Canada, 2002 to 2016
Year Atlantic Canada peak (99th percentile) 1-hour concentration
(parts per billion)
Southern Quebec peak (99th percentile) 1-hour concentration
(parts per billion)
Southern Ontario peak (99th percentile) 1-hour concentration
(parts per billion)
Prairies and northern Ontario peak (99th percentile) 1-hour concentration
(parts per billion)
British Columbia peak (99th percentile) 1-hour concentration
(parts per billion)
2002 69.0 55.5 88.7 71.4 45.1
2003 70.7 96.9 87.0 57.7 41.5
2004 61.8 101.2 87.0 65.0 35.1
2005 75.5 79.9 84.4 74.4 37.2
2006 73.8 83.4 78.4 59.0 42.1
2007 56.4 62.3 67.3 75.4 32.7
2008 36.8 53.7 68.9 70.5 40.8
2009 56.2 52.1 53.6 55.2 40.5
2010 35.7 54.0 53.5 66.4 34.5
2011 27.8 43.6 51.5 36.0 32.5
2012 28.5 52.1 54.8 33.0 33.6
2013 28.7 44.5 59.0 33.9 32.3
2014 32.2 41.4 61.3 33.0 22.6
2015 22.7 38.6 53.6 33.3 23.7
2016 18.6 44.6 48.0 30.4 21.9
Annual trend -4.0 -3.2 -2.9 -3.0 -1.4
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How this indicator was calculated

Note: The peak SO2 indicator is based on the concentrations recorded at 6 monitoring stations in Atlantic Canada, 7 in southern Quebec, 6 in southern Ontario, 18 in the Prairies and northern Ontario region, and 22 in British Columbia. The horizontal dashed line represents the 1-hour standard of the 2020 Canadian Ambient Air Quality Standards. The Canadian Ambient Air Quality Standard is provided for illustrative purposes only and not for assessing the achievement status of the standards. Reporting of the achievement of the standards is done within specific jurisdictions using 3-year averages. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

In 2016, the highest peak concentration of SO2 was recorded in southern Ontario, at 48.0 ppb, while the lowest concentration was recorded in the Prairies and northern Ontario region, at 30.4 ppb.

Compared to the previous year, the peak concentration of SO2 in 2016 was 10% lower in southern Ontario, 9% lower in the Prairies and northern Ontario region, 18% lower in Atlantic Canada, and 7% lower in British Columbia. Southern Quebec's peak concentration was 15% higher than in 2015.

From 2002 to 2016, decreasing trends of 1.4 ppb, 2.9 ppb, 3.0 ppb, 3.2 ppb and 4.0 ppb per year were detected for British Columbia, southern Ontario, the Prairies and northern Ontario region, southern Quebec, and Atlantic Canada, respectively.

Peak sulphur dioxide concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the peak SO2 concentrations at specific monitoring stations.

Peak sulphur dioxide concentrations by monitoring station, Canada, 2016

Peak sulphur dioxide concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the peak concentrations of sulphur dioxide in 2016 by monitoring station. Stations are categorized by the concentration of sulphur dioxide measured in the air. The categories are as follows: 0 to 5 parts per billion, 5 to 15 parts per billion, 15 to 40 parts per billion, 40 to 70 parts per billion and 70 parts per billion or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

Volatile organic compounds

Volatile organic compounds

Volatile organic compounds (VOCs) are carbon-containing gases and vapours that are found in many common products such as gasoline and solvents.Footnote 11 Volatile organic compounds are emitted from the oil and gas industry, solvent usage and transportation. Some VOCs can cause cancer and serious health problems. VOCs contribute to the formation of fine particulate matter (PM2.5) and ozone (O3), which are the main components of smog.

Key results

  • In 2016, the average concentration of VOCs was 58 parts per billion carbon (ppbC), which is 36% lower than in 2002
  • Between 2002 and 2016, a decreasing trend was observed in the average concentration of VOCs

Volatile organic compounds concentrations, Canada, 2002 to 2016

Volatile organic compounds concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Volatile organic compounds concentrations, Canada, 2002 to 2016
Year Average concentration
(parts per billion carbon)
2002 91.3
2003 119.9
2004 108.6
2005 84.8
2006 92.2
2007 87.2
2008 84.9
2009 90.9
2010 80.7
2011 75.7
2012 65.9
2013 70.3
2014 65.1
2015 67.8
2016 58.4
Annual trend -3.3
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How this indicator was calculated

Note: The national average VOC concentration indicator is based on the annual average of the daily concentrations recorded at 38 monitoring stations across Canada. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information
The national average concentration of VOCs in the air was 14% lower in 2016 than the previous year. Since 2002, a decreasing trend of 3.3 ppbC per year has been detected. This is consistent with the reduction in VOC emissions from cars and trucks, which is attributable to the introduction of more stringent emissions standards and from reduction measures related to the production and use of solvents and paints.

Regional ambient levels

Key results

  • In 2016, annual average concentrations of VOCs in the air varied by region, from 35.2 ppbC in southern Quebec to 93.8 ppbC in the Prairies and northern Ontario region
  • From 2002 to 2016, decreasing trends in average VOC concentrations were observed in all regions

Regional average volatile organic compounds concentrations, Canada, 2002 to 2016

Regional average volatile organic compounds concentrations, Canada, 2002 to 2016 (see data table below for the long description)
Data table for the long description
Regional average volatile organic compounds concentrations, Canada, 2002 to 2016
Year Atlantic Canada average concentration
(parts per billion carbon)
Southern Quebec average concentration
(parts per billion carbon)
Southern Ontario average concentration
(parts per billion carbon)
Prairies and northern Ontario average concentration
(parts per billion carbon)
British Columbia average concentration
(parts per billion carbon)
2002 103.6 74.4 68.3 150.6 114.9
2003 148.1 77.8 75.0 156.7 219.1
2004 110.0 63.4 62.6 141.5 275.5
2005 117.3 60.6 62.9 137.1 98.8
2006 123.1 60.8 60.7 136.1 161.8
2007 58.0 60.8 56.0 119.9 186.5
2008 111.5 47.6 44.7 148.0 139.8
2009 135.0 42.7 43.7 121.4 195.0
2010 88.7 44.8 41.1 109.1 189.9
2011 74.5 39.3 30.8 108.9 125.9
2012 100.7 37.6 42.3 109.2 94.1
2013 85.8 36.8 41.9 140.1 110.9
2014 85.1 36.7 38.7 107.4 113.1
2015 80.8 37.2 46.3 110.5 110.6
2016 65.5 35.2 37.1 93.8 85.4
Annual trend -3.7 -3.0 -2.5 -3.9 -7.2
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How this indicator was calculated

Note: The average VOC concentration indicator is based on the concentrations recorded at 5 monitoring stations in Atlantic Canada, 9 in southern Quebec, 13 in southern Ontario, 5 in the Prairies and northern Ontario region, and 6 in British Columbia. An up arrow indicates an increasing trend, a down arrow a decreasing trend, and an "X" no trend. For more information on the indicators, consult the Air quality indicators definitions in the Methods section.
Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

More information

Concentrations of VOCs were lower in 2016 than in 2015 for all regions. The annual average concentration of VOCs recorded for Atlantic Canada was 19% lower in 2016 than in 2015. The Prairies and northern Ontario region and British ColumbiaFootnote 12  had VOC concentrations that were 15% and 23% lower than in 2015. Southern Quebec and Southern Ontario recorded lower concentrations in 2016 than in 2015, with decreases of 5% and 20%, respectively.

From 2002 to 2016, decreasing trends of 3.7 ppbC, 3.0 ppbC, 2.5 ppbC, 3.9 ppbC and 7.2 ppbC per year were detected for Atlantic Canada, southern Quebec, southern Ontario, the Prairies and northern Ontario region, and British Columbia, respectively.

Volatile organic compounds concentrations at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada.

The Canadian Environmental Sustainability Indicators provide this information through an interactive map. With the interactive map, you can drill down to the VOC concentrations at specific monitoring stations.

Average volatile organic compounds concentrations by monitoring station, Canada, 2016

Average volatile organic compounds concentrations by monitoring station, Canada, 2016 (see below for long description)
Long description
The map of Canada shows the average concentrations of volatile organic compounds in 2016 by monitoring station. Stations are categorized by the concentration of volatile organic compounds measured in the air. The categories are as follows: 0 to 20 parts per billion carbon, 20 to 40 parts per billion carbon, 40 to 60 parts per billion carbon, 60 to 100 parts per billion carbon and 100 parts per billion carbon or more.

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2018) National Air Pollution Surveillance Program.

About the indicators

About the indicators

What the indicators measure

The Air quality indicators track ambient concentrations of fine particulate matter (PM2.5), ground-level ozone (O3), sulphur dioxide (SO2), nitrogen dioxide (NO2), and volatile organic compounds (VOCs) at the national, regional and urban levels and at local monitoring stations. The national and regional indicators are presented with their corresponding Canadian Ambient Air Quality Standard when available.

Why these indicators are important

Canadians are exposed to air pollutants on a daily basis, and this exposure can cause adverse health and environmental effects. Fine particulate matter (PM2.5) and ozone (O3), 2 of the most widespread air pollutants, are key components in the formation of smog. Exposure to these pollutants, even at low concentrations, has been associated with pulmonary and cardiovascular diseases. Furthermore, science indicates that there is no known threshold below which these 2 pollutants will not cause adverse health effects.

While causing adverse health effects of its own, SO2 also contributes to the formation of PM2.5 and acid deposition. Similarly, NO2 contributes to the formation of O3 and PM2.5, acid deposition and eutrophication. Volatile organic compounds are one of the main contributors to O3 and also contribute to the formation of PM2.5. There are thousands of individual VOC species. Some of the VOCs meet the definition of toxic under the Canadian Environmental Protection Act, 1999. Over a life-time, exposure to these pollutants can increase the risk of developing cancer and other serious health issues.

Consult the Air pollution: drivers and impacts web page for information on the human health, environmental and economic impacts of air pollution.

Related indicators

The International comparison of urban air quality indicators present and compare the air quality in selected Canadian urban areas with a population greater than one million to the air quality in selected international urban areas having comparable data

The Air pollutant emissions indicators track emissions from human-related sources of sulphur oxides (SOX), nitrogen oxides (NOX), volatile organic compounds (VOCs), ammonia (NH3), carbon monoxide (CO) and fine particulate matter (PM2.5).

The Air health trends indicator provides an overview of the public health impacts attributable to outdoor air pollution in Canada.

Safe and healthy communities

These indicators support the measurement of progress towards the following 2016–2019 Federal Sustainable Development Strategy long-term goal: All Canadians live in clean, sustainable communities that contribute to their health and well-being.
Data sources and methods

Data sources and methods

Data sources

The Air quality indicators are calculated from the air concentrations in the Canada-wide Air Quality Database. The database is maintained by Environment and Climate Change Canada's National Air Pollution Surveillance Program. It contains data collected through the following monitoring networks:

  • the National Air Pollution Surveillance Network, a collaboration established in 1969 between Environment and Climate Change Canada and provincial, territorial and regional (Metro Vancouver, ville de Montréal) governments
  • for ground-level ozone, the Canadian Air and Precipitation Monitoring Network operated by Environment and Climate Change Canada
    • the Canadian Air and Precipitation Monitoring Network stations were established to research and monitor air pollution outside urban areas
  • other provincial, territorial and municipal monitoring stations that report their air quality data to the Canada-wide Air Quality Database
More information

Air quality monitoring stations are spread across the country, but are more concentrated in urban areas. The indicators for fine particulate matter (PM2.5), ground-level ozone (O3), sulphur dioxide (SO2), nitrogen dioxide (NO2) and volatile organic compounds (VOCs) are provided nationally and by region. The regions used for these indicators are listed and shown in the following table and map. See Annex A for the full list of stations used to calculate the national and regional indicators.

Regions used for the regional Air quality indicators
Region Region code
Atlantic Canada ATL
Southern Quebec SQC
Southern Ontario SON
Prairies and northern Ontario PNO
British Columbia[A] BCO

Note: [A] For volatile organic compounds, only stations from the Metro Vancouver area were available to be used for the British Columbia regional indicator.

Regions used for the regional Air quality indicators

Regions used for the regional Air quality indicators (see below for long description)
Long description
The map of Canada shows the five regions that are used for the regional Air quality indicators. The regions are, from east to west, Atlantic Canada, southern Quebec, southern Ontario, Prairies and northern Ontario, and British Columbia.
The Air quality indicators are also reported for the larger urban areas in Canada and the capitals of the provinces and territories when data are available. An urban area follows the definition of the Statistic Canada's census metropolitan area and census agglomeration. See Annex F for the full list of stations used to calculate the urban area indicators. Ambient levels of PM2.5, O3, SO2, NO2 and VOCs by monitoring station are also shown in the Canadian Environmental Sustainability Indicators' interactive indicator maps.

Data quality assurance and quality control for the National Air Pollutant Surveillance program

Monitoring agencies contributing to the National Air Pollution Surveillance program all strive to adhere to established quality assurance and quality control standards, which are developed by Environment and Climate Change Canada in consultation with the provincial, territorial and regional governments participating in the program.

Ensuring data quality involves identifying the appropriate data quality objectives and the methodologies that can be used to meet these objectives. The key data quality objectives for the National Air Pollution Surveillance program are:

  • representativeness, referring to the degree to which data measurements represent a pollutant concentration of interest
  • comparability, a measure of confidence with which one data set or method can be compared to another at other participating National Air Pollutant Surveillance program sites across Canada
  • accuracy, the assessment of the overall agreement of a measurement with a known value
    • accuracy can include assessments of agreement among repeated measurements (precision) and measures of positive or negative systematic errors (bias)
  • completeness, the assessment as to whether enough information is being collected to ensure confidence in conclusions or decisions made on the basis of data
Accuracy data quality objectives for air pollutant samples
Parameter Accuracy
Fine particulate matter ± 15%
Ground-level ozone ± 15%
Sulphur dioxide ± 15%
Nitrogen dioxide ± 15%
Volatile organic compounds Species-dependent

Routine assessments of network operations provide assurance that the monitoring systems and data processing procedures produce an acceptable level of data quality to meet National Air Pollution Surveillance guidelines and to identify areas where improvements may be required. Three (3) main streams of audits and assessment are used in the National Air Pollution Surveillance network:

  • performance and systems audits, which are conducted externally either by an Environment and Climate Change Canada auditor or by another agency separate from the monitoring agency
    • these audits are performed using independently verified reference standards, and provide an unbiased quantitative assessment to defend the quality of the data
  • interagency measurement program, which involves analysis by the monitoring agency of an unknown sample concentration provided by Environment and Climate Change Canada
    • these tests help verify instrument accuracy, and help determine data comparability across sites
  • data quality assessments, which involve the statistical analysis of environmental data to determine if collected and reported data meet network and data quality objectives

Additional audits and assessments are performed by Environment and Climate Change Canada's air quality laboratories in Ottawa for the analysis of integrated VOC samples. Consult the NAPS Monitoring and Quality Assurance and Quality Control Guidelines report for more information.Footnote 13 

Methods

The Air quality indicators are calculated using air pollutant concentrations measured at monitoring sites and stored in the Canada-wide Air Quality Database. The concentrations are then averaged to estimate the national, regional and urban indicators. Further analysis is done to determine the presence of significant trends for the national and regional indicators.

More information
Air quality indicators definitions
Indicator Definition Concentration measurement unit[A]
Average PM2.5 Annual average of the daily 24-hour average concentrations µg/m3
Peak PM2.5 Annual 98th percentile of the daily 24-hour average concentrations µg/m3
Average O3 Annual average of the daily maximum 8-hour average concentrations ppb
Peak O3 Annual 4th-highest of the daily maximum 8-hour average concentrations ppb
Average SO2 Annual average of the hourly concentrations ppb
Peak SO2 Annual 99th percentile of the daily maximum 1-hour average concentrations ppb
Average NO2 Annual average of the hourly concentrations ppb
Peak NO2 Annual 98th percentile of the daily maximum 1-hour average concentrations ppb
Average VOC Annual average of the daily 24-hour average concentrations ppbC

Note: [A] Units: µg/m3 = micrograms per cubic metre, ppb = parts per billion, ppbC = parts per billion carbon.

Average indicators are used to capture prolonged or repeated exposures over longer periods or chronic exposure while peak indicators are used to capture immediate or acute short-term exposures.

Canadian Ambient Air Quality Standards

In October 2012, the Ministers of the Environment, with the exception of QuebecFootnote 14 agreed to begin implementing the new Air Quality Management System. This system provides a comprehensive, cross-Canada framework for collaborative action to further protect human health and the environment through continuous improvement of air quality. The Canadian Ambient Air Quality Standards (the standards) drive air quality management across the country. The standards are health and environment based air quality objectives for pollutant concentrations in outdoor air. Together with the management levels,Footnote 15 the standards act as a benchmark to support continuous improvement of air quality. In May 2013 for PM2.5 and O3, in October 2016 for SO2 and in November 2017 for NO2, the federal government established the standards as objectives under the Canadian Environmental Protection Act, 1999.

Calculation of the Air quality indicators follow the same data-handling conventions as those used in calculating the values of the standards. It is important to note that the achievement of the standards for PM2.5, O3, SO2 and NO2 is calculated using 3-year averages of the measured concentrations at the local level, while the indicator values are calculated at the national and regional levels using a single year only. As such, comparisons of the indicator values to the standards are provided for illustrative purposes only and not for assessing whether the standards are achieved. Furthermore, the indicators are not adjusted for exceptional events or for pollution from transboundary flows. The following table provides details of the standards.

 

Canadian Ambient Air Quality Standards for fine particulate matter, ground-level ozone, sulphur dioxide and nitrogen dioxide
Pollutant Averaging time 2020 Standard
(numerical value)
Statistical form
PM2.5 24-hour (calendar day) 27 µg/m3 The 3-year average of the annual 98th percentile of the daily 24-hour average concentrations
PM2.5 Annual (calendar year) 8.8 µg/m3 The 3-year average of the annual average of the daily 24-hour average concentrations
O3 8-hour 62 ppb The 3-year average of the annual 4th-highest of the daily maximum 8-hour average concentrations
SO2 1-hour 70 ppb The 3-year average of the annual 99th percentile of the daily maximum 1-hour average concentrations
SO2 Annual (calendar year) 5.0 ppb The arithmetic average over a single calendar year of all 1-hour average concentrations
NO2 1-hour 60 ppb The 3-year average of the annual 98th percentile of the daily maximum 1-hour average concentrations
NO2 Annual (calendar year) 17.0 ppb The arithmetic average over a single calendar year of all 1-hour average concentrations

Data collection and validation

Data obtained from National Air Pollution Surveillance monitoring stations are converted to a format compatible with the Canada-wide Air Quality Database. All data in the Canada-wide Air Quality Database have a comparable level of quality because jurisdictions adhere to established quality assurance and quality control procedures as outlined in the National Air Pollution Surveillance Monitoring and Quality Assurance/Quality Control Guidelines. These procedures include site and sampling system design, use of monitoring methods that meet defined minimum performance specifications, operation, maintenance and calibrations, and data validation techniques. National Air Pollution Surveillance monitoring organizations are responsible for submitting quality-assured data, as per the specifications in the Guidelines, to the Canada-wide Air Quality Database. Data submitted to the National Air Pollution Surveillance database are in the hour-ending format (that is, minute data collected between 01:01 and 02:00 are averaged and reported as the 02:00 hour).

Data completeness criteria

The following criteria are used to determine which stations have sufficient hourly and daily measurements in each year to be considered valid for inclusion in the indicators. These are largely based on the specifications set out in the Canadian Council of Ministers of the Environment's Guidance Document on Achievement Determination: Canadian Ambient Air Quality Standards for Fine Particulate Matter and Ozone (PDF; 265 kB).

For fine particulate matter (PM2.5):

  • a valid day has data for at least 18 hours (75%)
  • a station is included only when
    • at least 75% of days in the calendar year are valid and
    • at least 60% of days in each quarter (3 months)Footnote 16 of a calendar year are valid

For the peak (98th percentile) 24-hour PM2.5 indicator, a station is also included if it exceeds the 24-hour standard of 28.0 micrograms per cubic metre (µg/m3), even if the above data completeness criteria are not satisfied.

For ground-level ozone (O3):

  • a valid 8-hour period has data for at least 6 hours (75%)
  • a valid day requires data for at least 18 hours (75%)
  • a station is included only when at least 75% of days in the combined second and third quarters (April 1 to September 30) are valid

For the peak (4th-highest) 8-hour O3 indicator, a station is also included if it exceeds the 8-hour standard of 63 parts per billion (ppb), even if the above data completeness criteria are not satisfied.

For average sulphur dioxide (SO2):

  • a station is included only when at least 75% of hourly averages in the calendar year are valid and
  • at least 60% of hourly averages in each quarter (3 months) of a calendar year are valid

For peak (99th percentile) 1-hour sulphur dioxide (SO2):

  • a valid daily maximum 1-hour average has hourly data for at least 18 hours (75%)
  • a station is included only when
    • at least 75% of days in the calendar year are valid
    • at least 60% of days in each quarter (3 months) of a calendar year are valid

For the peak (99th percentile) 1-hour SO2 indicator, a station is also included if it exceeds the 1-hour standard of 70 ppb, even if the above data completeness criteria are not satisfied.

For average nitrogen dioxide (NO2):

  • a station is included only when at least 75% of hourly averages in the calendar year are valid and
  • at least 60% of hourly averages in each quarter (3 months) of a calendar year are valid

For peak (98th percentile) 1-hour nitrogen dioxide (NO2):

  • a valid daily maximum 1-hour average has hourly data for at least 18 hours (75%)
  • a station is included only when
    • at least 75% of days in the calendar year are valid and
    • at least 60% of days in each quarter (3 months) of a calendar year are valid

For the peak (98th percentile) 1-hour NO2 indicator, a station is also included if it exceeds the 1-hour standard of 60 ppb, even if the above data completeness criteria are not satisfied.

There are fewer data for volatile organic compounds (VOCs), and therefore data completeness criteria are different. At urban monitoring stations, VOC samples are usually collected over a 24-hour period once every 6 days, and, at rural stations, samples are collected over a 4-hour sampling period (12:00 to 16:00) once every 3 days. For VOCs, data completeness criteria are as follows:

  • a valid day requires data for a consecutive period of 24 hours at an urban station and for a consecutive 4 hours at a rural station
  • a valid quarter (3 months) requires data for at least 5 samples
  • a station is included only if the year has 3 valid quarters
Number of stations that satisfied the data completeness criteria for 2016
Indicator Number of stations
Peak (98th percentile) 24-hour PM2.5 187
Average PM2.5 187
Peak (4th-highest) 8-hour O3 199
Average O3 190
Peak (99th percentile) 1-hour SO2 97
Average SO2 91
Peak (98th percentile) 1-hour NO2 154
Average NO2 159
VOCs 38

After the data completeness criteria have been met, the pollutant concentrations are calculated for the selected stations.

Pollutant-specific calculations

Fine particulate matter

The PM2.5 average and peak (98th percentile) 24-hour indicators are based on the 24-hour daily average concentrations (daily average) for the whole year. The daily average value for PM2.5 is measured from midnight to midnight.

For a given station, the average indicator is calculated by summing all valid daily averages and dividing by the number of valid days. The peak (98th percentile) 24-hour indicator is obtained by determining the 98th percentile value of all 24-hour daily values for a given year. The 98th percentile value corresponds to the concentration for which 98% of all the daily 24-hour values are less than it and 2% are greater than or equal to it. For example, the 98th percentile value of 25 µg/m3 at a given station means that 98% of all daily 24-hour average concentrations are less than 25 µg/m3, and only 2% are equal to or greater than 25 µg/m3. The following table provides the rank of the 98th percentile value based on the number of available daily measurements.Footnote 17 

98th percentile rank based on the number of available measurements
Number of available daily measurements in a year 98th percentile rank
274 to 300 6th highest
301 to 350 7th highest
351 to 366 8th highest

The urban area, regional and national indicators (average and peak [98th percentile] 24-hour) for PM2.5 are calculated by averaging the station-level annual average and station-level annual peak values for selected stations within either the urban area, the region or Canada as a whole.

Ground-level ozone

Ozone concentrations are calculated in parts per billion (ppb). There are 24 consecutive 8-hour average concentrations (8-hour rolls) that can possibly be calculated for each day. The highest value of the 24 averaged concentrations is the daily maximum. An illustration of the 8-hour averages is provided in the figure below.

Calculation of the ground-level ozone daily maximum 8-hour average concentration

Calculation of the ground-level ozone daily maximum 8-hour average concentration (see below for long description)
Long description
This figure shows an example of the calculation of one daily maximum 8-hour average concentration. The figure shows hourly concentrations, the 8-hour moving average and the daily maximum. The concentration is calculated in parts per billion. There are 24 consecutive 8-hour moving average concentrations (8-hour rolls) that can possibly be calculated for each day. The highest value of those 24 concentrations is the daily maximum.

For each station, the average O3 indicator is calculated by taking the average of the daily maximum 8-hour (ending) averages for the period from January 1 to December 31. The urban area, regional and national averages for O3 are obtained by averaging the station-level annual averages for selected stations within the urban area, the region or Canada as a whole.

For each station, the peak (4th-highest) 8-hour O3 indicator is based on the 4th-highest of the daily maximum 8-hour average concentrations measured over a given year. All of the daily maximum 8-hour average concentrations are ordered in an array from highest to lowest, with equal values repeated as often as they occur. Each value is assigned a rank. For a given year, the 4th-highest ranking value in the array is identified as the annual peak (4th-highest) 8-hour O3 concentration for that station. The urban area, regional and national peak O3 indicators are obtained by averaging all 4th-highest values from selected stations within the urban area, the region or Canada as a whole.

Sulphur dioxide

The SO2 average is based on the annual average of the hourly concentrations while the peak (99th percentile) 1-hour indicator is based on the annual 99th percentile of the daily maximum 1-hour average concentrations. The daily maximum 1-hour average value for SO2 is measured from midnight to midnight.

For a given station, the average indicator is calculated by summing all valid hourly averages and dividing by the number of total hours. The peak (99th percentile) 1-hour indicator is obtained by determining the 99th percentile value of all 24-hour daily maximum values for a given year. The 99th percentile value corresponds to the concentration for which 99% of all the daily 24-hour maximum values are less than it and 1% is greater than or equal to it. For example, the 99th percentile value of 65 ppb at a given station means that 99% of all daily maximum 1-hour average concentrations are less than 65 ppb, and only 1% are equal to or greater than 65 ppb. The following table provides the rank of the 99th percentile value based on the number of available daily measurements.

99th percentile rank based on the number of available measurements
Number of available daily measurements in a year 99th percentile rank
274 to 300 3rd highest
301 to 366 4th highest

The national, regional and urban area indicators (average and peak [99th percentile] 1-hour) for SO2 are calculated by averaging the station-level annual average and station-level annual peak values for selected stations within the urban area, the region or throughout Canada.

Nitrogen dioxide

The NO2 average is based on the annual average of all hourly concentrations while the peak (98th percentile) 1-hour indicator is based on the annual 98th percentile of the daily maximum 1-hour average concentrations. The daily maximum 1-hour average value for NO2 is measured from midnight to midnight.

For a given station, the average indicator is calculated by summing all valid hourly averages and dividing by the number of total hours. The peak (98th percentile) 1-hour indicator is obtained by determining the 98th percentile value of all daily maximum values for a given year. The 98th percentile value corresponds to the concentration for which 98% of all the daily maximum values are less than it and 2% is greater than or equal to it. For example, the 98th percentile value of 25 ppb at a given station means that 98% of all daily maximum 1-hour average concentrations are less than 25 ppb, and only 2% are equal to or greater than 25 ppb. The national, regional and urban area indicators (average and peak [98th percentile] 1-hour) for NO2 are calculated by averaging the station-level annual average and station-level annual peak values for selected stations within the urban area, the region or Canada as a whole.

Volatile organic compounds

Urban VOC station indicators are calculated from daily average concentrations (24-hour average concentrations) while rural VOC station indicators are calculated from daily 4-hour average (from 12:00 to 16:00) concentrations. The daily 24-hour average concentrations are based on measurements taken from midnight to midnight. For a station, the average indicator is calculated by taking the average of the daily concentrations for a given year.

The national, regional and urban area average indicators for VOCs are obtained by averaging the station-level annual averages from selected stations within the urban area, the region and throughout Canada.

While the concentration unit for individual VOCs is usually ppb, parts per billion carbon (ppbC) are used in these indicators to assess the quantity of mixed VOC species.

Station selection criteria for inclusion in national and regional indicators (time‑series)

Station-level indicators were calculated for the years 2002 to 2016 for all air pollutants. Each station was then assessed for its suitability (sufficient data, no large gaps at the beginning or end) for inclusion in the national and regional time series. The specific criteria are as follows:

  • for the national and regional time series, a station is included if it satisfies the data completeness criteria for at least 11 of the 15 years
  • stations are excluded if data are missing for at least 2 consecutive years at the beginning or end of the time series
    • this measure avoids the use of data from stations that were commissioned or decommissioned at the beginning or end of the time series

In addition to the time series selection criteria, a minimum of 3 monitoring stations are required to calculate the indicator for a region, for a given year.

Station selection results

The following table indicates the number of monitoring stations that satisfied the selection criteria (data completeness and time series) and were thus included in the national and regional Air quality indicators for the time series. Further details on the stations selected are available in Annex A.

Number of stations selected for the national and regional Air quality indicators for 2016
Indicator Canada Atlantic Canada Southern Quebec Southern Ontario Prairies and northern Ontario British Columbia
Peak (98th percentile) 24-hour PM2.5 114 8 30 35 20 19
Average PM2.5 109 8 28 33 20 19
Peak (4th-highest) 8-hour O3 155 18 40 38 29 29
Average O3 153 17 40 38 29 28
Peak (99th percentile) 1-hour SO2 68 6 7 8 25 21
Average SO2 65 5 7 7 24 21
Peak (98th percentile) 1-hour NO2 89 6 15 22 21 25
Average NO2 101 7 15 25 27 26
VOCs 38 5 9 13 5 6

Note: The sum of the regional stations do not match all the time the national station numbers because stations from the Northwest Territories and Yukon were added to the national totals.

Local (station-level) indicators for O3, PM2.5, SO2, NO2 and VOCs are also presented in the Canadian Environmental Sustainability Indicators' interactive indicator maps. All stations displayed on the map satisfy the data completeness criteria.

Imputation

Stations that do not have enough measurements to meet the time series criteria for every year are excluded from the national and regional indicators. However, in some cases, monitoring stations are located close enough to others to allow data from neighbouring stations to be used to supplement missing data. Stations that were moved but remain relatively close to their previous location were also imputed. Annex B provides details on the stations that were used for imputation in the calculation of the time series.

Monitoring equipment

Fine particulate matter monitoring equipment

Five (5) types of monitoring equipment are used to monitor ambient PM2.5 concentrations:

  • older technology: Rupprecht & Patashnick tapered element oscillating microbalance (TEOM) monitor
  • current technology: Thermo Scientific TEOM 1400a with the Series 8500C Filter Dynamics Measurement System (FDMS) monitor
  • current technology: Met One BAM-1020 Beta Attenuation Mass monitor
  • current technology: Thermo Scientific 5030 or 5030i SHARP (Synchronized Hybrid Ambient Real-time Particulate) monitor
  • current technology: GRIMM Environmental Dust Monitor model EDM 180 and 365

The current technologies have been approved by the United States Environmental Protection Agency as Class III federal equivalent methods and have been deployed across the National Air Pollution Surveillance network replacing older tapered element oscillating microbalance instruments that have been found to exclude a portion of the PM2.5 mass from measurement. Further details on this technological transition are available in Annex C.

Ground-level ozone monitoring equipment

Ozone measurements are made using ultraviolet photometry. Sample air passes through a beam of light from an ultraviolet lamp, which is absorbed by O3. The amount of ultraviolet light absorbed is proportional to the amount of O3 in the sample.

Sulphur dioxide monitoring equipment

Sulphur dioxide measurements are made using pulse-fluorescence ultraviolet adsorption instruments. This technology is based on the principle that SO2 molecules absorb ultraviolet light at one wavelength and emit ultraviolet light at a different wavelength. The intensity of the emitted light is proportional to the number of SO2 molecules in the sample gas.

Nitrogen dioxide monitoring equipment

Nitrogen dioxide is measured by subtraction following measurement of the total of nitrogen oxides (NOX)Footnote 18 and nitrogen monoxide (NO) alone. NO concentrations are determined photometrically by measuring the light intensity from the chemiluminescent reaction of NO mixed with excess O3. The chemiluminescence method detects only NO, therefore, NO2 must first be converted to NO for measurement purposes. Sample flow either is directed through a converter to reduce NO2 to NO, or it bypasses the converter to allow detection of only NO. The sample stream with reduced NO2 is a measurement of NO plus NO2, which is expressed as NOX. The difference between NOX and NO detection is taken as the NO2 concentration.

Volatile organic compound monitoring equipment

The air samples are collected in either 6-litre or 3.2-litre stainless steel canisters. The canisters are then shipped to the Environment and Climate Change Canada analysis laboratory in Ottawa. A combined gas chromatography-flame ionization detector system is used for quantification of VOCs containing 2 carbons, while a combined gas chromatography-mass selective detector system operating in selected ion monitoring mode is used for quantification of VOCs containing 3 to 12 carbons. Approximately 120 VOCs (including a number of biogenic species such as isoprene and pinenes) are targeted for quantification in the samples, but not all VOCs are detectable in each sample. The total concentration of VOCs in parts per billion carbon is calculated from the total mass of all species detected in the sample. The list of VOCs targeted for quantification is provided in Annex D.

Statistical analysis

Non-parametric statistical tests were carried out on temporal concentration data to detect the presence of a linear trend and, if present, to determine the orientation (positive or negative) and magnitude of the rate of change (slope). The standard Mann-Kendall trend test was used to detect trend presence and orientation, while the Sen's pairwise slope method was used to estimate the slope. Results of the tests are available in Annex E. Both tests were applied to the regional and national data for O3, PM2.5, SO2, NO2 and VOCs. A trend was reported when the Mann-Kendall test indicated the presence of a trend at the 95% confidence level over the 15-year time series.

The following table presents the rate of change per year (slopes expressed in median annual percentage change, relative to the value in the first year of each time series) for the national and regional Air quality indicators over the reported time series from 2002 to 2016.

Rate of change per year for the national and regional Air quality indicators, 2002 to 2016
Indicator National
(median annual percent change)
Atlantic Canada
(median annual percent change)
Southern Quebec
(median annual percent change)
Southern Ontario
(median annual percent change)
Prairies and northern Ontario
(median annual percent change)
British Columbia
(median annual percent change)
PM2.5 average [A] 3.36 -1.48 [A] 3.59 [A]
PM2.5 peak (98th percentile) 24-hour [A] [A] -3.32 -3.30 10.37 [A]
O3 average [A] [A] [A] [A] [A] [A]
O3 peak (4th-highest) 8-hour -1.15 -1.65 -1.70 -1.81 [A] [A]
SO2 average -4.44 -6.72 -5.28 -4.84 -3.69 -3.20
SO2 peak (99th percentile) 1-hour -3.89 -5.36 -4.02 -3.22 -4.20 -3.10
NO2 average -3.09 -3.31 -3.47 -4.00 -2.20 -2.49
NO2 peak (98th percentile) 1-hour -1.94 -2.23 -2.31 -2.66 -0.76 -1.74
VOCs average -3.13 -2.89 -4.25 -3.61 -2.62 -3.77

Note: [A] Indicates that the Mann-Kendall method failed to reject the null hypothesis at the 95% confidence level, meaning a trend was not detected.

Calculation of Air quality indicators for urban areas

Urban areas are municipalities or cities defined by the census metropolitan area or the census agglomerations from Statistics Canada. A census metropolitan area or a census agglomeration is an area consisting of one or more neighbouring municipalities situated around a core. A census metropolitan area must have a total population of at least 100 000 of which 50 000 or more live in the core. A census agglomeration must have a core population of at least 10 000.

All the monitoring stations located within the census metropolitan area or census agglomeration are considered in the calculation only if they meet the same selection criteria used for the national and regional indicators. See the section on data completeness criteria.

Annual ambient levels from all monitoring stations found in the urban area are averaged. The average is a simple arithmetic average and is not weighted by the population covered by each station. This calculation is repeated for each indicator.

Only the urban areas for the most populated communities in Canada and the provincial and territorial capitals are reported for these indicators if they have sufficient data. Data for sulphur dioxide and volatile organic compounds were considered too sparse to allow for appropriate urban comparisons. For a complete list of the urban areas and monitoring stations found in these urban areas, consult Annex F.

Recent changes

The stations used to calculate the indicators vary slightly between different editions of the indicators. For more information, consult the caveats and limitations section under Revisions to station selections. Some air quality data of previous years were reassessed and corrected.

New SO2 and NO2 air quality indicators based on the Canadian Ambient Air Quality Standards were added to the set of indicators. The peak SO2 indicator is provided for the first time and is based on the annual 99th percentile of the daily maximum 1-hour average concentrations. The peak NO2 indicator is also provided for the first time and is based on the annual 98th percentile of the daily maximum 1-hour average concentrations. The average SO2 and NO2 indicators based on the annual average of the hourly concentrations are the same than the previous SO2 and NO2 indicators.

New Air quality indicators estimated by urban area for PM2.5, O3 and NO2 were added for the present release.

Caveats and limitations

Data completeness

Some data collected at stations cannot be used in calculating the indicators because the data do not meet the data completeness criteria. These criteria are based on standard practices supported by expert opinion and are used by a number of organizations, such as the World Health Organization, the Canadian Council of Ministers of the Environment and the United States Environmental Protection Agency. The criteria allow for some gaps in data.

Revisions to station selections

Monitoring stations are selected based on the 15-year time series criteria for the calculation of the Air quality indicators. As this is a rolling 15-year time period, the number of stations selected may vary from one edition of the indicators to the next and may change the historical trends. Caution is should be exercised when comparing different editions of the Air quality indicators.

The following table shows the number of stations removed, added, relocated or combined for PM2.5, O3, SO2, NO2 and VOC indicators.

Number of stations removed and number of new stations compared to December 2016 release of the Air quality indicators
Indicator Number of stations removed[A] Number of new or relocated stations Total number of stations used for the imputation Number of combined stations after imputation[B]
Peak (98th percentile) 24-hour PM2.5 3 52 36 17
Average PM2.5 6 50 29 14
Peak (4th-highest) 8-hour O3 10 24 51 23
Average O3 10 24 47 21
Peak (99th percentile) 1-hour SO2 n/a n/a 10 5
Average SO2 16 11 8 4
Peak (98th percentile) 1-hour NO2 n/a n/a 24 10
Average NO2 6 26 29 14
VOCs 2 9 18 9

Note: n/a = not applicable. [A] These stations no longer respect the time series criteria and were removed from the calculation of the national and regional indicators for the whole time series. [B] These stations were included in the calculation of the national and regional indicators. Annex B provides details on the stations that were used for imputation.

Regional air quality indicators

The number of available monitoring stations and pollutants measured varies from region to region. In certain years, regions that have close to the minimum number of monitoring stations required may record an unusual value if a particular monitoring station did not meet the completeness criteria for that year. This is especially true when the value obtained differs greatly from those obtained at other stations (overshadowing all the other stations). For this reason, the regional indicators may be subject to annual fluctuations.

Effect of new fine particulate matter measurement technologies

Since 2005, the Rupprecht & Patashnick tapered element oscillating microbalance (TEOM) monitors used in the National Air Pollution Surveillance program have gradually been replaced by newer monitoring technologies (federal equivalency method-approved instruments). Many studies conducted in Canada, the United States and other countries have found that the TEOM monitors under-report concentrations compared with the newer monitors, especially when the air contains a large proportion of semi-volatile particulate matter. This may be the case during cooler seasons when the air contains a greater proportion of ammonium nitrate and semi-volatile organic compounds.

Some of the year-to-year variations in the PM2.5 air quality indicators may be due, in part, to the introduction of the newer monitoring technologies across the National Air Pollution Surveillance Network rather than to changes in actual ambient concentrations only. As such, trends in PM2.5 concentrations may not be a true reflection of the changes that have occurred over the time period concerned (see Annex C).

Resources

Resources

References

Canadian Council of Ministers of the Environment (2011) Ambient Air Monitoring Protocol for PM2.5 and Ozone (PDF; 787 kB). Retrieved on May 4, 2018.

Canadian Council of Ministers of the Environment (2014) Air Quality Management System. Retrieved on May 4, 2018.

Environment and Climate Change Canada (2013) National Air Pollution Surveillance Program. Retrieved on May 4, 2018.

Dann T (2012) CESI PM2.5 Air Indicator Using Transformed Data. Prepared for Environment Canada.

Dann T (2013) Comparison of CESI PM2.5 Air Indicators with Transformed Data (FEM Basis). Prepared for Environment Canada.

Related information

Annexes
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