Emissions of harmful substances to air

Key results

• In 2023, mercury, lead and cadmium emissions had decreased by 91%, 91% and 95%, respectively from 1990 levels
• In 2023, arsenic facility-based emissions had decreased by 78% from 1993 levels^{Footnote 2} 

Percentage change of mercury, lead and cadmium emissions from 1990 level and arsenic emissions from 1993 level, Canada

How this indicator was calculated

Note: The indicator reports emissions from human-related activities only for mercury, lead and cadmium and facility-based emissions for arsenic. It does not include emissions from natural sources such as forest fires or volcanoes. Facility-based reporting for arsenic emissions did not begin until 1993.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory and National Pollutant Release Inventory.

The decreases in mercury, lead, cadmium and arsenic emissions are mostly attributed to large reductions in emissions from the non-ferrous smelting and refining industry. This decline was primarily due to the implementation of mandatory pollution prevention plans under CEPA 1999, closing of outdated smelters, compliance with federal and provincial legislation, and conformance with guidelines introduced over this period. The changes in facility processes and adoption of emission reduction technologies also contributed to the reduction of mercury emissions.

However, emissions of mercury have not changed substantially since 2011. This may be due to a range of competing factors such as increases in production levels offset by the ongoing implementation of cleaner technologies, facility closures and regulations coming into force in the earlier years.

While overall lead emissions declined between 1990 and 2023, they did increase slightly from 2014 to 2017 but continued to decline afterwards. These reductions are partly due to the closure of some non-ferrous metal smelting and refining facilities, the installation of more efficient emission control equipment, changes in lead concentrations in smelter feed and changes in production levels at some facilities. 

Cadmium emissions fluctuated between 1990 and 2006 but decreased steadily starting in 2007, before declining sharply in 2010. Fluctuations in cadmium emissions prior to 2010 are mostly driven by emissions from a non-ferrous smelting and refining facility in Manitoba that is now closed.

Reporting to the National Pollutant Release Inventory (NPRI) of facility-based arsenic emissions did not begin until 1993. Arsenic emissions from facilities fluctuated between 1993 and 2004 but decreased drastically in 2005 and continued to steadily decline since. Fluctuations in facility-based arsenic emissions prior to 2005 are mostly driven by a foundry facility in Quebec that was required to lower its arsenic emissions. Fluctuations were also driven by changes to NPRI reporting in 2002.

For more detailed information on emissions from industrial, commercial and institutional facilities, visit the Canadian Environmental Sustainability Indicator’s interactive maps.

Emissions of mercury to air

Mercury is a naturally occurring metal that can be emitted to the air by natural processes (like melting permafrost, volcanic activity, and soil and rock erosion), human activities (such as coal-fired electricity generation and waste incineration and treatment) and the improper disposal of mercury-containing products (such as batteries, thermometers, and fluorescent lamps).

Mercury emissions are both a local and a global concern. Mercury can travel long distances in the atmosphere and may settle anywhere in Canada, including in ecologically sensitive areas such as the Canadian Arctic and the Great Lakes. Mercury that has accumulated in the environment can be re-emitted into the atmosphere through natural processes, such as temperature change and microbial activity, or human activities that disturb mercury-laden sites. Re-emission of mercury is a more significant source of atmospheric mercury pollution than anthropogenic emissions from Canadian sources because it involves the release of mercury that has been accumulated over decades in the environment, which exceeds current direct emissions.^{Footnote 3} 

Mercury can have significant negative impacts on human health and the environment as mercury persists in the environment and accumulates in food chains over time, up to several decades. In humans, exposure poses a particular risk to populations who rely heavily on the consumption of aquatic and marine species, such as northern and Indigenous communities, whose traditional diets typically include predatory fish (for example, freshwater trout and Arctic char) and marine mammals.

This indicator reports on mercury emissions from human-related activities using data from the Air Pollutant Emissions Inventory (APEI).

Mercury emissions to air by source
Mercury emissions to air by province and territory
Mercury emissions to air from facilities
Global mercury emissions to air

Mercury emissions to air by source

Key results

• In 2023, 3.13 tonnes of mercury were emitted from anthropogenic sources in Canada
  • Combined emissions from the ore and mineral industries, including the non-ferrous smelting and refining industry (11% or 0.33 tonnes), the iron and steel industry (10% or 0.32 tonnes), other ore and mineral industries (8% or 0.26 tonnes) and the cement and concrete industry (6% or 0.19 tonnes), collectively emitted 35% (or 1.1 tonnes) of the annual total
  • Incineration and waste represented the highest emitting sector, emitting 28% (or 0.86 tonnes) of the annual total
• Between 1990 and 2023, mercury emissions decreased by 91% (or 30.4 tonnes) 

Mercury emissions to air by source, Canada, 1990 to 2023

How this indicator was calculated

Note: The indicator reports emissions from human-related activities only. It does not include emissions from natural sources such as forest fires or volcanoes. The category "other sources" includes agriculture (livestock, crop production and fertilizer), building heating and energy generation, home firewood burning, manufacturing, the oil and gas industry, transportation (road, rail, air and marine) and other miscellaneous sources. Other ore and mineral industries include the aluminum industry, the asphalt paving industry, cement and concrete, iron and steel industries, iron ore industry and mining and rock quarrying. For more details on the sources, consult the Data sources and methods. 
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

The largest reduction in mercury emissions from a single anthropogenic source between 1990 and 2023 was from the non-ferrous smelting and refining industry. This industry reduced its emissions by 98.7% (from 24.9 tonnes in 1990 to 0.33 tonnes in 2023), contributing to 81% of the overall emissions reduction of mercury. National emissions drastically decreased by 43% between 1992 and 1993 and have generally continued to steadily decrease since. The sharp decline in mercury emissions between 1992 and 1993 was largely due to a major process change at a smelter in Manitoba, which significantly reduced mercury emissions from what was, then, Canada's largest point source. Additional closures and modernizations of smelters across Canada and pollution prevention regulations and standards also helped reduce mercury emissions during this period.

The reductions between 1990 and 2023 were primarily due to changes in facility processes and adoption of emission reduction technologies, the closing of outdated smelters, compliance with federal and provincial legislation, and conformance with guidelines.

Between 1990 and 2023, emissions from electric utilities, and incineration and waste declined by 79% and 67% (1.8 and 1.7 tonnes), respectively. The decrease from electric utilities was largely due to the closure of coal-fired power plants.^{Footnote 4} Combined, these two sources contributed 11% to the total decrease in mercury emissions.

Mercury emissions to air by province and territory

Key results

• In 2023, Ontario (35%), British Columbia (18%) and Saskatchewan (16%) accounted for 68% of national mercury emissions
• Between 1994 and 2023,^{Footnote 5} Manitoba had the largest reduction in annual emissions with a decrease of 4.3 tonnes

Mercury emissions to air by province and territory, Canada, 1994, 2013 and 2023

How this indicator was calculated

Note: Emissions from the Northwest Territories for 1994 includes emissions from Nunavut, which was officially separated from the Northwest Territories in 1999. The indicator reports emissions from human-related activities only. It does not include emissions from natural sources such as forest fires or volcanoes. Some reported emissions from Newfoundland and Labrador, Prince Edward Island, New Brunswick, Yukon, the Northwest Territories and Nunavut are too small to see in the figure. To access all available years data please refer to the indicator’s interactive figures or, for the full dataset, to the Air Pollutant Emissions Inventory.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, Ontario had the highest mercury emissions, accounting for 35% (1.1 tonnes) of the national total. These emissions came mostly from the incineration and waste sector, the iron and steel industry, and the mining and rock quarrying industry, which together accounted for 58% of the total provincial emissions.

All provinces and territories had lower emissions in 2023 compared to 1994, with the caveat that Nunavut, which separated from the Northwest Territories in 1999 and thus lacks data for comparison to 1994. Manitoba had the largest decline in emissions between 1994 and 2023. This decline was mostly due to changes in zinc processing technology and production levels, and the closure of an outdated copper smelter at a non-ferrous smelting and refining facility.

Mercury emissions from most of the provinces and territories have declined or remained stable since 1994, except for Saskatchewan. The province had an overall increase in emissions from 1994 to 2008, followed by a gradual decline until 2014.

Alberta had the largest decrease in emissions between 2013 and 2023 (0.3 tonnes). This decline was largely from electric utilities, likely due to the closure of coal-fired power plants.^{Footnote 4} 

Mercury emissions to air from facilities

The National Pollutant Release Inventory provides detailed information on emissions from industrial, commercial and institutional facilities that meet its reporting criteria.

The Canadian Environmental Sustainability Indicators provide access to this information through an online interactive map. The map allows users to explore rates of mercury emissions to air from individual facilities.

In 2023, facility-reported mercury emissions represent 62% of total national mercury emissions.^{Footnote 6} Of these facilities:

• 59 facilities reported emissions under 0.5 kilogram (kg)
• 106 facilities reported emissions between 0.5 to 100 kg
• 3 facilities reported emissions over 100 kg, located in Saskatchewan (2) and British Columbia (1)

Mercury emissions to air by facility, Canada, 2023

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2025) National Pollutant Release Inventory.

Global mercury emissions to air

Mercury in the air can travel hundreds to thousands of kilometres via air masses before being deposited to the environment.^{Footnote 7}   Environment and Climate Change Canada  estimates that over 95% of the human-related mercury deposited in Canada came from sources outside of the country.^{Footnote 3}

Key results

• In 2015, the latest year for which data are available, global mercury emissions^{Footnote 8}  to air from human activity were estimated to be 2 220 tonnes
• The East and Southeast Asia, South America and Sub-Saharan Africa regions accounted for 73% of the global total
• The North America region (which includes only Canada and the United States) emitted 40 tonnes, or about 2% of the global total
  • Canada emitted less than 5 tonnes or about 0.2% of the global total

Global mercury emissions to air, 2015

How this indicator was calculated

Note: CIS = Commonwealth of Independent States. The CIS includes Armenia, Azerbaijan, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Moldova, Russian Federation, Tajikistan, Turkmenistan, Ukraine and Uzbekistan. The 28 member countries of the European Union includes Austria, Belgium, Bulgaria, Croatia, Republic of Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden and the United Kingdom. The North American region includes only Canada and the United States, Mexico is grouped into the Central America and the Caribbean region.
Source: United Nations Environmental Program (2019) Global Mercury Assessment 2018.

Emissions of lead to air

Lead is a naturally occurring metal found in the Earth's crust whichcan be released during natural processes, such as rock and soil erosion. However, in Canada, most lead emissions come from industrial activities, such as metal smelting and refining, and various combustion processes. Lead is also used in the manufacture of vehicle lead-acid batteries worldwide, as well as pipes, sheeting, and within glass to prevent radiation exposure from television and computer screens.

Lead emissions to air can be deposited on land or water surfaces and accumulate in soils, sediments, humans and wildlife. Exposure to lead, even in small amounts, can be hazardous to humans and wildlife. In humans, chronic exposure to relatively low levels may affect the central and peripheral nervous systems, blood pressure, and renal function, and may result in reproductive problems and developmental neurotoxicity.

This indicator reports on lead emissions from human-related activities using data from the Air Pollutant Emissions Inventory (APEI).

Emissions of lead to air by source
Emissions of lead to air by province and territory
Emissions of lead to air from facilities

Emissions of lead to air by source

Key results

• In 2023, 93.3 tonnes of lead were emitted in Canada
• The largest source of lead emissions has been the non-ferrous smelting and refining industry since 1990. These emissions accounted for 70% (or 65.3 tonnes) of total emissions in 2023
• Between 1990 and 2023, national lead emissions decreased by 91% (or 930.1 tonnes)

Lead emissions to air by source, Canada, 1990 to 2023

How this indicator was calculated

Note: The indicator reports emissions from human-related activities only. It does not include emissions from natural sources such as forest fires or volcanoes. The category "other sources" includes agriculture (livestock, crop production and fertilizer), building heating and energy generation, electric utilities, home firewood burning, incineration and waste, off-road vehicles and mobile equipment, the oil and gas industry, paints and solvents and other miscellaneous sources. The other ore and mineral industries include the aluminum industry, the asphalt paving industry, the cement and concrete industry, foundries, iron and steel industry, iron pelletizing mining and rock quarrying and the mineral products industry. For more details on the sources, consult the Data sources and methods.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

The largest reduction in lead emissions between 1990 and 2023 was from the non-ferrous smelting and refining industry (93% or 821 tonnes). The decline was due to the 2006 publication of a Pollution Prevention Planning Notice targeting base metal smelters and refineries and zinc plants (BMS P2 Notice)^{Footnote 11}  and the installation of more efficient emission control equipment in operating smelters, along with the closure of outdated smelters in 2010, 2018 and 2019. The majority of emissions prior to 2010 are due to 2 non-ferrous smelting and refining facilities, one located in Quebec and the other located in Manitoba.

From 2014 to 2017, national lead emissions increased slightly; however, emissions began to decrease gradually from 2018 onwards. The decrease in lead emissions is mostly attributable to the implementation of pollution prevention plans under the BMS P2 Notice and the implementation of the base-level industrial emissions requirements (BLIERs), and the development for the non-ferrous smelting and refining industry through environmental performance agreements (EPAs).^{Footnote 12}  Some fluctuations in national emissions may be due to changes in lead concentrations in smelter feed, changes in production levels at some facilities and the closure of smelters in Manitoba in 2018 and New Brunswick in 2019.

Lead emissions to air by province and territory

Key results

• In 2023, Quebec and Ontario accounted for 72% and 12% of national lead emissions, respectively
• Between 1994 and 2023,^{Footnote 5}  Manitoba had the largest decrease in annual emissions of 503.5 tonnes

Lead emissions to air by province and territory, Canada, 1994, 2013 and 2023

How this indicator was calculated

Note: Emissions from the Northwest Territories for 1994 includes emissions from Nunavut, which was officially separated from the Northwest Territories in 1999. The indicator reports emissions from human-related activities only. It does not include emissions from natural sources such as forest fires or volcanoes. Some reported emissions from Newfoundland and Labrador, Prince Edward Island, Nova Scotia, Saskatchewan, Yukon, the Northwest Territories and Nunavut are too small to see in the figure. Some legacy data for 1994 that cannot be attributed to any province or territory are excluded from the figure. To access all available years data please refer to the indicator’s interactive figures or, for the full dataset, to the Air Pollutant Emissions Inventory.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, Quebec had the highest lead emissions in Canada, accounting for 72% (66.9 tonnes) of national emissions. These emissions came mostly from the non-ferrous smelting and refining industry and accounted for 90% of the total provincial emissions.

Between 1994 and 2023, Manitoba and Quebec experienced the largest emission reductions with 503.5 tonnes (99.7%) and 316.2 tonnes (82.5%), respectively. These declines were mostly due to the reduced emissions from the non-ferrous smelting and refining industry.

New Brunswick and Newfoundland and Labrador had slight increases in lead emissions between 1994 and 2013, although emissions in both provinces declined between 2013 and 2023.

In most provinces, emissions continued to decrease or remained stable from 2013 to 2023, except for Quebec. Ontario had the largest decrease in emissions (14.3 tonnes, 56%) between 2013 and 2023, largely from the non-ferrous smelting and refining industry. This decrease was mostly due to process changes and the implementation of pollutant prevention plans under the BMS P2 Notice combined with the implementation of the EPAs.

Lead emissions to air from facilities

The National Pollutant Release Inventory provides detailed information on emissions from industrial, commercial and institutional facilities that meet its reporting criteria.

The Canadian Environmental Sustainability Indicators provide access to this information through an online interactive map. The map allows you to explore lead emissions to air from individual facilities.

In 2023, facility-reported lead emissions represent 82% of total national lead emissions.^{Footnote 6}   Of these facilities:

• 122 facilities reported emissions under 0.5 kilogram (kg)
• 230 facilities reported emissions between 0.5 to 200 kg
• 17 facilities reported emissions over 200 kg, located in Quebec (8), Ontario (5), British Columbia (1), Alberta (1), Saskatchewan (1), and Newfoundland and Labrador (1) 
  • One (1) non-ferrous smelting and refining facility in Quebec accounted for 56% (or 58,911 kg) of the total facility-reported emissions of lead in 2023

Lead emissions to air by facility, Canada, 2023

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2025) National Pollutant Release Inventory.

Emissions of cadmium to air

Cadmium is a naturally occurring metal in the Earth's crust. This metal can be released during natural processes, such as weathering and erosion of cadmium-bearing rocks, forest fires, and volcanic activity. Human activity can also contribute to cadmium emissions, such as through the manufacture of batteries, electroplating, power generation and heating, transportation, solid waste disposal, and sewage sludge application.

Exposure to cadmium can be hazardous to both humans and wildlife since cadmium accumulates in the food chain over time. The Government of Canada has concluded that cadmium compounds may be harmful to the environment and may constitute a danger based on their carcinogenic potential. Human exposure to cadmium has been associated with gastrointestinal irritation and harmful effects on the kidneys and bones.

This indicator reports on cadmium emissions from human-related activities using data from the Air Pollutant Emissions Inventory (APEI).

Emissions of cadmium to air by source
Emissions of cadmium to air by province and territory
Emissions of cadmium to air from facilities

Emissions of cadmium to air by source

Key results

• In 2023, 4.3 tonnes of cadmium were emitted in Canada
• Since 1990, the largest source of cadmium emissions has been the non-ferrous smelting and refining industry. It accounted for 47% (or 2.0 tonnes) of the national total in 2023
• Between 1990 and 2023, cadmium emissions decreased by 95% (or 76.8 tonnes)

Cadmium emissions to air by source, Canada, 1990 to 2023

How this indicator was calculated

Note: The indicator reports emissions from human-related activities only. It does not include emissions from natural sources such as forest fires or volcanoes. The category "other sources" includes agriculture (livestock, crop production and fertilizer), electric utilities, home firewood burning, incineration and waste, oil and gas industry, transportation (road, rail, air and marine) and other miscellaneous sources. Other ore and mineral industries include the aluminum industry, the asphalt paving industry, the cement and concrete industry, foundries, the iron and steel industry, iron pelletizing, mining and rock quarrying and mineral products industry. For more details on the sources, consult the Data sources and methods.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

Between 1990 and 2023, cadmium emissions from the non-ferrous smelting and refining industry declined by 97% (76.2 tonnes). This decline was responsible for nearly all of the reduction in national cadmium emissions between 1990 and 2023. The decline was due to the closure of outdated smelters in 2010, 2018 and 2019 and the implementation of pollution prevention plans under the base metal smelter and refineries and zinc plants Pollution Prevention Notice (BMS P2 Notice)^{Footnote 11}  combined with the implementation of the Environmental Performance Agreements (EPAs).^{Footnote 12} 

The fluctuations in cadmium emissions prior to 2010 were mostly driven by changes in emissions from a single non-ferrous smelting and refining facility in Manitoba that is now closed. 

Cadmium emissions to air by province and territory

Key results

• In 2023, Ontario and Quebec accounted for 72% (3.1 tonnes) of national cadmium emissions
• Between 1994 and 2023,^{Footnote 5}  Manitoba had the largest decline in emissions (59.7 tonnes)

Cadmium emissions to air by province and territory, Canada, 1994, 2013 and 2023

How this indicator was calculated

Note: Emissions from the Northwest Territories for 1994 includes emissions from Nunavut, which was officially separated from the Northwest Territories in 1999. The indicator reports emissions from human-related activities only. It does not include emissions from natural sources such as forest fires or volcanoes. Some reported emissions from Newfoundland and Labrador, Prince Edward Island, Nova Scotia, Manitoba, Saskatchewan, Yukon, the Northwest Territories and Nunavut are too small to see in the figure. Legacy data for 1994 that cannot be attributed to any province or territory are excluded from the figure. To access all available years data please refer to the indicator’s interactive figures or, for the full dataset, to the Air Pollutant Emissions Inventory.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, Ontario and Quebec reported the highest cadmium emissions of all the provinces and territories, accounting for 37% (1.6 tonnes) and 35% (1.5 tonnes) of national emissions, respectively. These emissions came mostly from the non-ferrous smelting and refining industry, manufacturing industries, and building heating and energy generation.

Between 1994 and 2023, emissions declined or remained stable for all provinces and territories, except Alberta and Newfoundland and Labrador. During this period, Manitoba experienced the largest decline in cadmium emissions (99.9% or 59.7 tonnes).

While Ontario, Alberta, and Newfoundland and Labrador had higher cadmium emissions in 2013 compared to 1994, emissions from all provinces and territories continued to decrease or remained stable from 2013 to 2023. Manitoba experienced the largest decline between 2013 and 2023 (1.6 tonnes), largely from the non-ferrous smelting and refining industry. This decrease was mostly due to the closure of a smelter in 2018. 

Cadmium emissions to air from facilities

The National Pollutant Release Inventory provides detailed information on emissions from industrial, commercial and institutional facilities that meet its reporting criteria.

The Canadian Environmental Sustainability Indicators provide access to this information through an online interactive map. The map allows you to explore cadmium emissions to air from individual facilities.

In 2023, facility-reported cadmium emissions represent 74% of total national cadmium emissions.^{Footnote 6}  Of these facilities:

• 130 facilities reported emissions under 0.5 kilogram (kg)
• 116 facilities reported emissions between 0.5 to 20 kg
• 17 facilities reported emissions over 20 kg, located in Alberta (7), Quebec (4), Ontario (3), British Columbia (1), Saskatchewan (1) and Newfoundland and Labrador (1)

Cadmium emissions to air by facility, Canada, 2023

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2025) National Pollutant Release Inventory.

Emissions of arsenic to air

Arsenic is a naturally occurring element released in aquatic and terrestrial environments from natural weathering and rock and soil erosion. Arsenic is also released to the environment from sources such as mining and rock quarrying, metal processing, wood preservation, coal-fired power generation and arsenical pesticides.

Exposure to arsenic can be hazardous to humans and wildlife as it accumulates in the food chain over time. The Government of Canada concluded inorganic arsenic compounds may be harmful to the environment and may constitute a danger to human health based on their carcinogenic potential. In humans, exposure to arsenic has been associated with heart disease, decreased lung function and harmful effects to the skin.

This indicator reports on arsenic^{Footnote 9}  emissions from facility-based reporting to the National Pollutant Release Inventory (NPRI). The NPRI provides detailed information on emissions from industrial, commercial and institutional facilities that meet its reporting criteria.

Emissions of arsenic to air by source
Emissions of arsenic to air by province and territory
Emissions of arsenic to air from facilities

Emissions of arsenic to air by source

Key results

• In 2023, 15.4 tonnes of arsenic were emitted in Canada from facilities
• In 2023, the largest source of arsenic emissions from facilities was the non-ferrous smelting and refining industry, accounting for 89% (or 13.7 tonnes) of the national total
• Between 1993 and 2023, arsenic facility-based emissions decreased by 78% (or 56.2 tonnes)

Facility-based arsenic emissions to air by source, Canada, 1993 to 2023

How this indicator was calculated

Note: The indicator reports emissions from facilities only. It does not include emissions from natural sources such as forest fires or volcanoes. The category "other sources" includes incineration and waste, manufacturing, the oil and gas industry and other miscellaneous sources. Other ore and mineral industries include foundries, the iron and steel industry, mining and rock quarrying and mineral products industry. For more details on the sources, consult the Data sources and methods.
Source: Environment and Climate Change Canada (2025) National Pollutant Release Inventory.

Between 1993 and 2023, facility-based arsenic emissions from the non-ferrous smelting and refining industry declined by 42% (9.8 tonnes). This decline was responsible for 17% of the total reduction in national arsenic emissions between 1993 and 2023. The decline was due to the closure of outdated smelters in 2010, 2018 and 2019 and the implementation of pollution prevention plans under the base metal smelter and refineries and zinc plants Pollution Prevention Notice (BMS P2 Notice)^{Footnote 11}  combined with the implementation of the Environmental Performance Agreements (EPAs).^{Footnote 12} 

Before 2010, most of the changes in facility-based arsenic emissions were caused by a single non-ferrous metal smelting and refining facility located in Manitoba, which has since shut down. Similarly, fluctuations in arsenic emissions before 2005 were largely influenced by a smelter in Quebec. In addition, in 2002, the federal government implemented the Metal and Diamond Mining Effluent Regulations to limit arsenic pollution into waters across Canada. As a result of these regulations, a mining and rock quarrying facility in Ontario significantly reduced its emissions. Fluctuations were also driven by changes to NPRI air emissions reporting in 2002.

Arsenic emissions to air by province and territory

Key results

• In 2023, Ontario and Quebec accounted for 91% (14 tonnes) of national arsenic facility-based emissions
• Between 2003 and 2023,^{Footnote 10}  Ontario had the largest decline in emissions (53.9 tonnes)

Arsenic emissions to air by province and territory, Canada, 2003, 2013 and 2023

How this indicator was calculated

Note: The indicator reports emissions from facility-based activities only. It does not include emissions from natural sources such as forest fires or volcanoes. Some reported emissions from Newfoundland and Labrador, Prince Edward Island, Nova Scotia, New Brunswick, Manitoba, Saskatchewan, Yukon, the Northwest Territories and Nunavut are too small to see in the figure. To access all available years data please refer to the indicator’s interactive figures or, for the full dataset, to the Air Pollutant Emissions Inventory.
Source: Environment and Climate Change Canada (2025) National Pollutant Release Inventory.

In 2023, Quebec and Ontario reported the highest arsenic emissions from facilities of all the provinces and territories, accounting for 76% (11.8 tonnes) and 14% (2.2 tonnes) of national emissions, respectively. These emissions came mainly from the non-ferrous smelting and refining industry.

Note: [A] In 2023, no facility-based arsenic emissions were reported in Prince Edward Island.

Between 2003 and 2023, reported arsenic emissions decreased in all the province and territories, except for Newfoundland and Labrador and Saskatchewan. Ontario experienced the largest decrease between 2003 and 2023 (53.9 tonnes), largely from the non-ferrous smelting and refining industry. This decrease was mostly due to process changes and the implementation of pollution prevention plans under the BSM P2 Notice combined with the implementation of the EPAs.

While Newfoundland and Labrador, Prince Edward Island, New Brunswick and Saskatchewan had higher arsenic emissions in 2013 compared to 2003, emissions from all provinces and territories continued to decrease or remained stable from 2013 to 2023. Quebec experienced the largest decline between 2013 and 2023 (7.6 tonnes), largely from the non-ferrous smelting and refining sector.

Yukon, Northwest territories and Nunavut had no reported emissions in 2003. Yukon had no reported emissions in 2013. Prince Edward Island was the only province that had no reported facility-based arsenic emissions in 2023.

Arsenic emissions to air from facilities

The National Pollutant Release Inventory provides detailed information on emissions from industrial, commercial and institutional facilities that meet its reporting criteria.

The Canadian Environmental Sustainability Indicators provide access to this information through an online interactive map. The map allows you to explore arsenic emissions to air from individual facilities.

In 2023, 199 facilities across Canada reported arsenic releases. Of these facilities:

• 89 facilities reported emissions under 1 kilogram (kg)
• 88 facilities reported emissions between 1 to 20 kg
• 22 facilities reported emissions over 20 kg, located in Ontario (6), British Columbia (5), Quebec (4), Alberta (2), Newfoundland and Labrador (2), Saskatchewan (2) and Nunavut (1)

Arsenic emissions to air by facility, Canada, 2023

Navigate data using the interactive map

How this indicator was calculated

Source: Environment and Climate Change Canada (2025) National Pollutant Release Inventory.

About the indicators

What the indicators measure

These indicators track human-related emissions to air of 3 substances (mercury, lead and cadmium) and facility-based emissions to air of 1 substance (arsenic). The 4 substances are defined as toxic under the Canadian Environmental Protection Act, 1999. For each substance, data are provided at the national, regional (provincial and territorial) and facility level, and by source. Global emissions data are also provided for mercury.

Why these indicators are important

Mercury and its compounds, lead, inorganic cadmium compounds and  inorganic arsenic compounds are on the Toxic substances list under Schedule 1 of the Canadian Environmental Protection Act, 1999. This means that these substances are "entering or may enter the environment in a quantity or concentration or under conditions that (a) have or may have an immediate or long-term harmful effect on the environment or its biological diversity; (b) constitute or may constitute a danger to the environment on which life depends; or (c) constitute or may constitute a danger in Canada to human life or health."

The indicators inform Canadians about emissions of mercury, lead and cadmium to air from human activity and emissions of arsenic from facility-based reporting in Canada. These indicators also help the government to identify priorities and develop or revise strategies to inform further risk management and to track progress on policies put in place to reduce or control these 4 substances and air pollution in general.

Related initiatives

These indicators support the measurement of progress towards the following 2022 to 2026 Federal Sustainable Development Strategy Goal 11: Improve access to affordable housing, clean air, transportation, parks, and green spaces, as well as cultural heritage in Canada. 

In addition, the indicators contribute to the Sustainable Development Goals of the 2030 Agenda for Sustainable Development. They are linked to the 2030 Agenda's Goal 11: Sustainable Cities and Communities and Target 11.6: "By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management."

Related indicators

The Releases of harmful substances to water indicators track human-related releases to water of 4 toxic substances, namely mercury, lead, cadmium and arsenic, and their compounds. For each substance, data are provided at the national, provincial/territorial, facility level and by source.

The Human exposure to harmful substances indicators track the concentrations of 4 substances (mercury, lead, cadmium and bisphenol A) in Canadians.

The Air pollutant emissions indicators track emissions from human activities of 6 key air pollutants: sulphur oxides (SO_X), nitrogen oxides (NO_X), volatile organic compounds (VOCs), ammonia (NH₃), carbon monoxide (CO) and fine particulate matter (PM_2.5). Black carbon, which is a component of PM_2.5, is also reported. Mercury, lead, cadmium and arsenic can also be components of particulate matter. Data are provided for each air pollutant at the national, provincial/territorial, facility level and by major source.

The Air quality indicators track ambient concentrations of fine particulate matter (PM_2.5), ozone (O₃), sulphur dioxide (SO₂), nitrogen dioxide (NO₂), and volatile organic compounds (VOCs) at the national and regional levels and at local monitoring stations.

Data sources and methods

Data sources

Data for the indicators for mercury, lead and cadmium are based on emission estimates reported in the Air Pollutant Emissions Inventory. The inventory data are available online on the Open Data website. Facility data for the arsenic indicator and the interactive maps for the 4 substances come from the National Pollutant Release Inventory, which are also available on Open Data.

Global mercury emissions data were taken from the United Nations Environment Programme's Global Mercury Assessment 2018 report.

Methods

The indicators are produced by grouping the calculated emissions data from Canada's national inventories to report on the key sources that contribute to the majority of mercury, lead, cadmium and arsenic emissions.

Recent changes

The emission estimates reported in Canada’s Air Pollutant Emissions Inventory used in the indicators undergo continuous improvements, leading to recalculations. For more information about these recent changes, consult Annex 3 of the Air Pollutant Emissions Inventory Report.

A new substance, arsenic, has been included in this indicator using data from the National Pollutant Release Inventory.

Caveats and limitations

Total emissions of mercury, lead, cadmium and arsenic to air reported in these indicators exclude natural sources such as forest fires or volcanoes. Arsenic reflects only facility-based emissions to air as reported to the National Pollutant Release Inventory (NPRI). They do not include estimates of emissions from other sources, such as emissions from cities, transboundary pollution or consumer products in Canada. 

To provide a consistent global picture, Canadian mercury emissions data used for the international comparison came from the United Nations Environment Programme's Global Mercury Assessment 2018 report. However, it is important to note that the emissions data found in this report were estimated using different estimation techniques and different source classifications than the data used for the national indicators. In addition, some sources were not quantified in the international comparison due to a lack of data.

The methods used to estimate air pollutant emissions continue to evolve. In general, improvements are made every year to methodologies for estimating emissions. As a result of these improvements, emissions for a given year may differ from those previously published by the department. Caution is advised when comparing different reports and different sources.

Prior to the launch of the NPRI, emissions data were collected and compiled by provincial, territorial and regional environmental authorities. As such, in the provincial/territorial comparisons in the indicators, the base year used differs from that used in the national indicators. Furthermore, some legacy data for 1994 could not be attributed to any province or territory. The legacy data were captured under unspecified region in the data tables.

Resources

References

Environment and Climate Change Canada (2016). Canadian Mercury Science Assessment Report. Retrieved on April 7, 2025. 

United Nations Environment Programme (2019) Global Mercury Assessment 2018. Retrieved on April 7, 2025.

Environment and Climate Change Canada (2025) Using and interpreting data from the National Pollutant Release Inventory. Retrieved on April 7, 2025.

Environment and Climate Change Canada (2025) Canada's Air Pollutant Emissions Inventory: overview. Retrieved on April 7, 2025.

Environment and Climate Change Canada (2025) National Pollutant Release Inventory bulk data. Retrieved on April 7, 2025.

Related information

NPRI sector overview: Aluminium

NPRI sector overview: Electricity

NPRI sector overview: Metal ore mining

Alternative format

Download the alternative format of the Emissions of harmful substances to air indicator (PDF; 1.5 MB).

Updated August 2025

These interactive figures support the Emissions of harmful substances to air indicator. Use them to explore the latest emissions of mercury, lead, cadmium and arsenic in a dynamic and customizable format.

Select data by using the drop-down menu above each figure and clear your selections by clicking the "Reset figures" button on the right-hand side of the dashboard. All values in the figures will automatically update based on your selections.

You can also choose to use your keyboard to navigate the figures.

Note: The charts are defaulted to show the national total and trends. When filtering for multiple provinces and territories, the cumulative total and trends will be reflected on the chart. Analysis of long-term regional trends should be interpreted with caution. Legacy data prior to 2005 could not be attributed to any province or territory and are classified as emissions from an unspecified region. The fluctuations in lead and cadmium emissions prior to 2010 are mostly driven by emissions from a single non-ferrous refining and smelting facility in Manitoba.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory and National Pollutant Release Inventory.

Download data file (Excel/CSV; 11 MB)