Air pollutant emissions

Between 1990 and 2018, the largest emission reductions were observed for SO_X, which decreased by 73%. It was followed by CO emissions (54% reduction), VOCs (37%), NO_X (25%) and PM_2.5 (11%). These reductions since 1990 are due in part to government actions and voluntary initiatives from key industrial emitters that were put in place to restrict or eliminate the release of air pollutants in Canada. For PM_2.5, since 2010, emissions have been steadily increasing outweighing the reductions observed over the period. Compared to 2017, there has been a slight upward trend in all the pollutants with the exception of SO_X.

In 2018, the majority of emissions of the 6 key air pollutants in Canada came from ore and mineral industries, transportation, the oil and gas industry, agriculture, and dust and fires (for example, road dust, prescribed burning).

Distribution of air pollutant emissions by source, Canada, 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation. The category "dust and fires" includes emissions from human activities such as prescribed burning and dust from roads. Consult Table 2 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

The human made sources most contributing to Canada's air pollutant emissions in 2018 were the following:

• the oil and gas industry, ore and mineral industries and electric utilities together represented the majority of SO_X emissions
• transportation (road, rail, air and marine) was a key source of NO_X and CO emissions
• off-road vehicles and mobile equipment and home firewood burning were also important sources of CO emissions and the oil and gas industry was an important source of NO_X emissions
• most of the VOC emissions came from the oil and gas industry and from the use of paints and solvents
• agriculture (livestock, crop production and fertilizer) accounted for the majority of NH₃ emissions
• dust and fires were the most important sources of PM_2.5 emissions

At the provincial level, emissions of the 6 key air pollutants in 2018 were:

• the highest in Alberta for SO_X, (27% of national emissions), NO_X (36%), VOCs (31%), NH₃ (27%) and PM_2.5 (33%)
• the highest in Quebec for CO (28%)
• the second highest in Ontario for SO_X (18% of national emissions), VOCs (21%) and CO (24%)
• also important in British Columbia for NO_X and Saskatchewan for NH₃ and PM_2.5, accounting for 16%, 21% and 30% of the national emissions of these pollutants

Distribution of air pollutant emissions by province and territory, Canada, 2018

How this indicator was calculated

Note:  The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

Sulphur oxide emissions by source

Emissions of sulphur oxides (SO_X)  in the atmosphere can have adverse effects on human health and the environment. The SO_X emissions released by human activities consist mostly of sulphur dioxides (SO₂). Sulphur dioxide can affect respiratory systems of humans and animals and cause damage to vegetation, buildings and materials. It is also a precursor to fine particulate matter (PM_2.5) and acid rain.

Key results

• Between 1990 and 2018, SO_X emissions decreased by 73% to 811 kilotonnes (kt) in 2018
• In 2018, three sources accounted for 91% (741 kt) of the total SO_X emissions: the oil and gas industry, ore and mineral industries and electric utilities

Total sulphur oxide emissions by source, Canada, 1990 to 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation. The category "other sources" includes emissions from transportation (road, rail, air and marine), off-road vehicles and mobile equipment, home firewood burning, incineration and waste, agriculture (livestock, crop production and fertilizer), dust and fires, paints and solvents, building heating and energy generation, manufacturing, and other miscellaneous sources. Consult Table 2 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The numbers have been rounded off and their sum may not correspond to the total.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

In 2018, the oil and gas industry and the ore and mineral industries each accounted for approximately 32% of total national SO_X emissions (261 kt and 259 kt respectively). Electric utilities followed with 27% (220 kt) of national emissions. For the ore and mineral industries, 54% (140 kt) of its SO_X emissions came from the non-ferrous refining and smelting industry.

The largest reduction in emissions between 1990 and 2018 was from ore and mineral industries with a reduction in emissions of 1 222 kt. The largest driver of the reduction from the source was from the non-ferrous refining and smelting industry with a reduction of 1 132 kt over the period.

This significant decrease in SO_X emissions from 1990 to 2018 is due in large part to government actions to fight acid rain and related federal-provincial and United States agreements^{Footnote 1 Footnote 2} on capping SO_X emissions by 1994. Further reductions were also realized through:

• technological upgrades, new air pollution controls for non-ferrous metal smelters and the closure of 3 major smelters in Manitoba, Ontario and Quebec
• lower emissions from fossil-fuel-fired (for example, coal-fired) power-generating utilities as a result of better technologies and plant closures (for example, the phase-out of coal electricity generation in Ontario)
• better emission control technologies within the oil and gas sector
• implementation of regulations on low-sulphur fuels^{Footnote 3 Footnote 4} 

Sulphur oxide emissions by province and territory

Key results

• In 2018, Ontario and Alberta accounted for 46% (369 kt) of national SO_X emissions
• Between 1990 and 2018,
  • the largest reduction was observed in Ontario. Emissions in the province decreased by 980 kt (87%)
  • Saskatchewan was the only province that experienced an increase in SO_X (21%, or 20 kt)

Sulphur oxide emissions by province and territory, Canada, 1990 and 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

Alberta had the highest SO_X emissions level in 2018, accounting for 27% (223 kt) of total national emissions. Emissions in the province mainly came from the oil and gas industry and electric utilities, combined accounting for 94% (210 kt) of the emissions.

Ontario was the second-highest emitter of SO_X in 2018, accounting for 18% (146 kt) of total national emissions. Ore and mineral industries were the largest contributor to SO_X emissions of the province in 2018. The sharp reduction in SO_X emissions in Ontario between 1990 and 2018 was mainly due to emission reductions from ore and mineral industries (notably the non-ferrous refining and smelting industry) and electric utilities.

Saskatchewan ranked third, with 14% (117 kt) of total national emissions; electric utilities was the most important source of emissions in the province.

Sulphur oxide emissions by facilities

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

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

Sulphur oxide emissions by reporting facilities, Canada, 2018

Note: Facility-reported sulphur oxide emissions represent 90% of total national sulphur oxide emissions.
Source: Environment and Climate Change Canada (2020) National Pollutant Release Inventory.

Navigate data using the interactive map

Nitrogen oxide emissions by source

Nitrogen oxides (NO_X) include emissions of nitric oxide (NO) and nitrogen dioxide (NO₂). Nitrogen dioxide can have adverse effects on human health and the environment. Nitrogen oxides contribute to acid rain, which can lead to the acidification of aquatic and terrestrial ecosystems. It also contributes to the eutrophication of lakes and to the formation of ground-level ozone (O₃) and fine particulate matter (PM_2.5).

Key results

• In 2018, NO_X emissions were 1 768 kilotonnes (kt). This is 25% lower than in 1990
• Transportation (road, rail, air and marine) was a major source of NO_X representing 41% (723 kt) of total emissions in 2018

Total nitrogen oxide emissions by source, Canada, 1990 to 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation. The category "other sources" includes emissions from ore and mineral industries, manufacturing, building heating and energy generation, home firewood burning, incineration and waste, agriculture (livestock, crop production and fertilizer), dust and fires, paints and solvents, and other miscellaneous sources. Consult Table 2 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The numbers have been rounded off and their sum may not correspond to the total.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

While transportation (road, rail, air and marine) was the main contributor of NO_X, it was also the sector that experienced the largest reduction between 1990 and 2018. Emissions of NO_X from this sector decreased by 260 kt (26%) during that period. 

The oil and gas industry emitted the next largest proportions of NO_X emissions in 2018, representing 27% (486 kt) of total national emissions. This sector also experienced the largest increase 41% (140 kt) in emissions between 1990 and 2018, partly offsetting reductions from other sectors.

The decline in NO_X emissions between 1990 and 2018 is mostly attributable to 2 factors:

• the reduction in emissions from transportation after 2000, given the progressive introduction of cleaner technology and fuels for vehicles
• lower emissions from fossil-fuel-fired (for example, coal-fired) power-generating utilities as a result of better emission control technologies and certain plant closures (for example, the closure of coal power plants in Ontario)

Nitrogen oxide emissions by province and territory

Key results

• Among provinces and territories, Alberta emitted the most NO_X in 2018. The province accounted for 36% (638 kt) of national emissions
• Between 1990 and 2018,
  • the largest reduction was observed in Ontario. Emissions decreased by 320 kt (53%) in the province
  • NO_X emissions slightly increased in Saskatchewan and increased by (23%, or 3 kt) for Nunavut and Northwest Territories combined

Nitrogen oxide emissions by province and territory, Canada, 1990 and 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

The oil and gas industry is an important source of NO_X emissions in Alberta, accounting for 60% (380 kt) of the province's NO_X emissions in 2018. The increasing contribution of this sector to the province's emissions between 1990 and 2018 was offset by emission reductions from the transport and electric utilities sectors.

Ontario and British Columbia both contributed the second-largest proportion of NO_X emissions in 2018, each accounting for 16% (279 kt) of total national emissions, with transportation (road, rail, air and marine) being the most important source in both provinces followed by off-road vehicles and mobile equipment in Ontario and the oil and gas industry in British Columbia. However, Ontario experienced the largest decrease in emissions levels (320 kt) between 1990 and 2018 in large part due to emission reductions from transportation, electric utilities and off-road vehicles and mobile equipment.

Quebec ranked fourth, with 12% (219 kt) of total national emissions. Transportation (road, rail, air and marine) was the most important source of NO_X in this province.

Nitrogen oxide emissions by facilities

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

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

Nitrogen oxide emissions by reporting facilities, Canada, 2018

Note: Facility-reported nitrogen oxide emissions represent 32% of total national nitrogen oxide emissions.
Source:  Environment and Climate Change Canada (2020) National Pollutant Release Inventory.

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Volatile organic compound emissions by source

Volatile organic compounds (VOCs) are carbon-containing gases and vapours released into the atmosphere by natural sources and human activities. ^{Footnote 5} There are hundreds of VOCs that are emitted and that affect the health of Canadians and the environment. VOCs are primary precursors to the formation of ground-level ozone and particulate matter which are the main pollutants contributing to the formation of smog.

Key results

• In 2018, VOC emissions in Canada were 1 914 kilotonnes (kt). This is a 1 123 kt (37%) decrease from 1990 levels
• Since 2000, the oil and gas industry has been the highest contributor to VOC emissions. In 2018, the sector accounted for 35% (674 kt) of total emissions

Total volatile organic compound emissions by source, Canada, 1990 to 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation. The category "other sources" includes emissions from incineration and waste, ore and mineral industries, dust and fires, building heating and energy generation, electric utilities, agriculture (livestock, crop production and fertilizer) and other miscellaneous sources. Consult Table 2 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The numbers have been rounded off and their sum may not correspond to the total.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

The oil and gas industry was the main source of VOC emissions in 2018 with 674 kt emitted (35% of total emissions). Paints and solvents and home firewood burning were also important sources contributing 22% (412 kt) and 12% (228 kt) of total emissions.

The source with the largest emissions reduction between 1990 and 2018 was off-road vehicles and mobile equipment, with emissions reductions of 676 kt (83%). 

The long-term decrease in VOC emissions is mainly attributable to 3 factors:

• the progressive introduction of cleaner technologies and fuels resulting in emission reductions from transportation, off-road vehicles and mobile equipment
• emission reductions from most industrial and non-industrial sources from improved emission controls
• lower levels of VOCs in products such as paints, solvents and cleaners

The two sources with significant emissions growth over the 1990 to 2018 period were the oil and gas industry with an increase of 74 kt (12%) and the use of paints and solvents with an increase of 55 kt (15%).

The recent increase in VOC emissions can be attributed to the use of paints and solvents, transportation and the oil and gas industry. 

Volatile organic compound emissions by province and territory

Key results

• Alberta emitted the highest proportion of VOCs in 2018. The province represented 31% (593 kt) of national emissions
• Between 1990 and 2018,
  • Ontario experienced the largest reduction in VOC emissions. Emissions in the province decreased by 56% (506 kt)
  • Saskatchewan was the only province that experienced an increase in VOC emissions (55%, or 93 kt)

Volatile organic compound emissions by province and territory, Canada, 1990 and 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

Alberta was the highest emitting province of VOCs in 2018 (593 kt), with the oil and gas industry as the main source, contributing 72% (425 kt) of the province's emissions.

Ontario was the second-highest emitter of VOCs, accounting for 21% (397 kt) of total national emissions in 2018. The main emission sources are paints and solvents, home firewood burning and off-road vehicles and mobile equipment. Ontario also experienced the largest reduction in emissions, with 506 kt (56%) between 1990 and 2018, mainly as a result of emission reductions from off-road vehicles and mobile equipment and transportation (road, rail, air and marine).

Quebec was the third largest emitter, with 16% (315 kt) of total national emissions, where home firewood burning and paints and solvents accounted for 62% of the emissions in that province.

Most provinces and territories experienced significant reductions in emissions between 1990 and 2018 with the exception of Saskatchewan, where emissions increased 55% over the period. The oil and gas industry is responsible for the increase in emissions in Saskatchewan.

Volatile organic compound emissions by facilities

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

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

Volatile organic compound emissions by reporting facilities, Canada, 2018

Note: Facility-reported volatile organic compound emissions represent 13% of total national volatile organic compound emissions.
Source:  Environment and Climate Change Canada (2020) National Pollutant Release Inventory.

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Ammonia emissions by source

Ammonia (NH₃) is a colourless gas with a noticeable odour at high concentrations. It can be poisonous if inhaled in great quantities and is irritating to the eyes, nose, and throat. It can also contribute to the nitrification and eutrophication of aquatic systems. In the air, the gas combines with sulphates and nitrates to form secondary fine particulate matter (PM_2.5).

Key results

• In 2018, NH₃ emissions were 484 kilotonnes (kt). This is 21% higher than in 1990
• Agriculture (livestock, crop production and fertilizer) was the main source of NH₃ emissions in 2018. Emissions from this source accounted for more than 93% (453 kt) of total national emissions

Total ammonia emissions by source, Canada, 1990 to 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation. The category "other sources" includes emissions from incineration and waste, the oil and gas industry, home firewood burning, ore and mineral industries, electric utilities, building heating and energy generation, off-road vehicles and mobile equipment, dust and fires, paints and solvents, and other miscellaneous sources. Consult Table 2 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The numbers have been rounded off and their sum may not correspond to the total.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

Between 1990 and 2018, agriculture (livestock, crop production and fertilizer) experienced the largest increase (25% or 90 kt) in NH₃ emissions. It also remained the key source of NH₃ emissions throughout that period. Emissions from manufacturing (12 kt), other sources (12 kt), and transportation (road, rail, air and marine) (8 kt) combined represented 7% of national emissions in 2018.

The growth in NH₃ emissions from agriculture (livestock, crop production and fertilizer) between 1990 and 2018 is mainly due to the increased use of synthetic nitrogen fertilizers. Up to 2005, larger livestock populations also added to the growth. However, from 2006 to 2011, livestock populations decreased and have since remained stable. More recently, emissions from crop production have been steadily increasing since 2006.

Ammonia emissions by province and territory

Key results

• In 2018, Alberta and Saskatchewan accounted for almost half (234 kt) of national NH₃ emissions
• Between 1990 and 2018,
  • Ontario experienced the largest emissions reduction. Emissions in the province decreased by 23 kt (21%)
  • The largest increase in NH₃ emissions was in Saskatchewan. Emissions in the province more than doubled (a 54 kt increase)

Ammonia emissions by province and territory, Canada, 1990 and 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

In 2018, Alberta emitted the most NH₃ of all the provinces and territories, accounting for 27% (131 kt) of total national emissions. Saskatchewan contributed the second-largest proportion of NH₃, representing 21% (103 kt).

Ontario and Quebec followed with 18% and 14% (90 kt and 69 kt) of total national emissions, respectively. For all provinces, livestock farms and the application of fertilizers were the most important sources of NH₃ emissions.

Almost all of the increase in emissions between 1990 and 2018 took place in Saskatchewan, Alberta and Manitoba.

Ammonia emissions by facilities

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

The Canadian Environmental Sustainability Indicators provide access to this information through an interactive map. The map allows you to explore NH₃ emissions from individual facilities.

Ammonia emissions by reporting facilities, Canada, 2018

Note: Facility-reported ammonia emissions represent 4% of total national ammonia emissions.
Source: Environment and Climate Change Canada (2020) National Pollutant Release Inventory.

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Carbon monoxide emissions by source

Carbon monoxide (CO) is a colourless, odourless, tasteless and poisonous gas. Once inhaled into the bloodstream, it can inhibit the blood's capacity to carry oxygen to organs and tissues, affecting human health.

Key results

• In 2018, CO emissions in Canada were 5 752 kilotonnes (kt), a decrease of 54% from 1990 levels
• Transportation (road, rail, air and marine) was the largest source of CO emissions in Canada. In 2018, the sector represented 33% (1 902 kt) of total emissions

 Total carbon monoxide emissions by source, Canada, 1990 to 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation. The category "other sources" includes emissions from dust and fires, electric utilities, building heating and energy generation, incineration and waste, agriculture (livestock, crop production and fertilizer), paints and solvents, ore and mineral industries, manufacturing and other miscellaneous sources. Consult Table 2 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The numbers have been rounded off and their sum may not correspond to the total.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

In 2018, transportation, off-road vehicles and mobile equipment, and home firewood burning were the 3 most important sources of CO. These sources combined represented 76% (4 399 kt) of national emissions.

The largest reduction in emissions between 1990 and 2018 occurred in transportation (road, rail, air and marine) with an emission decrease of 3 619 kt (66%).

The decline in CO emissions between 1990 and 2018 is mainly due to increasingly stringent engine and vehicle regulations and the progressive introduction of cleaner and more efficient technology in vehicles (for example, catalytic converters).

Carbon monoxide emissions by province and territory

Key results

• In 2018, Ontario and Quebec accounted for 52% (3 009 kt) of national CO emissions
• Between 1990 and 2018,
  • all provinces and territories experienced significant reductions in emissions
  • the largest reductions occurred in Ontario (by 2 130 kt or 60%), British Columbia (by 1 649 kt or 69%) and Quebec (by 1 069 kt or 40%)

Carbon monoxide emissions by province and territory, Canada, 1990 and 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

In 2018, Quebec emitted the most CO of all the provinces and territories, representing 28% (1 601 kt) of the total national emissions. Home firewood burning was the most important source of CO emissions for Quebec.

The province of Ontario ranked second, with 24% (1 409 kt) of total national emissions in 2018, with 37% of those emissions from transportation (road, rail, air and marine).

Alberta, the third largest CO emitter, accounted for 18% (1 032 kt) of total national emissions. The oil and gas industry accounted for 42% of the province's CO emissions.

The sharp decrease in emissions between 1990 and 2018 in all provinces is mainly attributable to emission reductions from transportation (road, rail, air and marine).

Carbon monoxide emissions by facilities

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

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

Carbon monoxide emissions by reporting facilities, Canada, 2018

Note: Facility-reported carbon monoxide emissions represent 15% of total national carbon monoxide emissions.
Source:  Environment and Climate Change Canada (2020) National Pollutant Release Inventory.

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Fine particulate matter emissions by source

Particulate matter (PM) is directly emitted into the air in solid or liquid form. It is also formed in the air from precursor substances such as sulphur oxides, nitrogen oxides, volatile organic compounds and ammonia.[1] Fine particulate matter (PM_2.5) refers to particulate matter with a size of less than 2.5 micrometres (also called microns). It is one of the major components of smog. When inhaled deeply into the lungs, even small amounts of PM_2.5 can cause serious health problems. It can also damage vegetation and structures, contribute to haze and reduce visibility.

Key results

• In 2018, PM_2.5 emissions were 1 625 kilotonnes (kt). This is 11% lower than in 1990
• Emissions from dust and fires (for example, road dust and prescribed burning) accounted for the majority of PM_2.5 emissions, reaching 59% (955 kt) of total national emissions in 2018. These emissions increased by 80% (425 kt) between 1990 and 2018. Dust from construction operations and unpaved roads accounted for the majority of the increase.

Total fine particulate matter emissions by source, Canada, 1990 to 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires and from vegetation. The category "other sources" includes emissions from ore and mineral industries, transportation (road, rail, air and marine), manufacturing, off-road vehicles and mobile equipment, the oil and gas industry, building heating and energy generation, electric utilities, incineration and wastes, paints and solvents, and other miscellaneous sources. Consult Table 2 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The numbers have been rounded off and their sum may not correspond to the total.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

In 2018, 82% of PM_2.5 emissions came from open source emissions, such as dust and fires, and agriculture (livestock^{Footnote 7} , crop production and fertilizer). In general, these emissions are spread over large geographical areas, are highly dependent on weather conditions (for example, wind and rain) and are located outside of urban areas.

The remaining 18% of PM_2.5 emissions in 2018 came from home firewood burning (161 kt or 10%) and other sources, including:

• ore and mineral industries, representing 2% (34 kt) of the emissions
• transportation (road, rail, air and marine), representing 1% (21 kt)
• manufacturing and off-road vehicles and mobile equipment, each representing about 1% (16 kt) of emissions
• miscellaneous sources, such as emissions from cigarette smoking, representing 1% (16 kt)
• the oil and gas industry, representing less than 1% (12 kt)
• other emissions (less than 1%) coming from building heating and energy generation, electric utilities, incineration and wastes, and the use of paints and solvents

Many of the sources above, despite representing a small proportion of national emissions, can have a disproportionate impact on the population because they are generally concentrated in populated areas.

The decreases in PM_2.5 emissions between 1990 and 2018 are mainly attributable to emission reductions from agriculture (livestock, crop production and fertilizer), home firewood burning and manufacturing. These reductions outweigh the increase in emissions from dust and fires over the period. The adoption of conservation practices in crop production and the use of new fireplace inserts, furnaces and stoves in homes that control emissions and burn more efficiently were the main drivers leading to the reductions. Since 2010, however, emissions from dust and fires have gradually increased outweighing reductions from the other sources.

Black carbon emissions by source

Black carbon is a component of PM_2.5 and is generated by the incomplete combustion of fossil fuels and biomass. It is a short-lived climate pollutant, and is linked to both climate warming and adverse human health effects. Reductions in black carbon emissions have near-immediate and local benefits.

Key results

• Emissions of black carbon were 37 kt in 2018, a slight increase from 2017 when emissions were 36 kt
• In 2018, 3 sectors accounted for 88% of national black carbon emissions:
  • home firewood burning
  • transportation (road, rail, air and marine)
  • off-road vehicles and mobile equipment

Total black carbon emissions by source, Canada, 2013 to 2018

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. It does not include emissions from natural sources such as forest fires. The chart includes emissions from the most significant sources of black carbon. "Other sources" includes emissions from ore and mineral industries, manufacturing, electric utilities and agriculture. Consult Table 2 in the Data sources and methods for more details.
Source: Environment and Climate Change Canada (2020) Canada's Black Carbon Emissions Inventory.

In 2018, home firewood burning and transportation (road, rail, air and marine) accounted for the largest proportions of total national emissions, both representing 31% (12 kt and 11 kt) of emissions. Off-road vehicles and mobile equipment (for example, lawn and garden equipment, recreational vehicles, excavators, graders) were also large contributors, representing about 26% (10 kt) of total national emissions. The remaining 12% of emissions came from the oil and gas industry, building heating and energy generation and other sources (such as ore and mineral industries).

For both transportation and off-road vehicles and mobile equipment, the use of diesel engines was the main source of black carbon emissions.

Black carbon emissions by province and territory

Key results

• In 2018, Quebec and Ontario accounted for 46% (17 kt) of total national black carbon emissions
• Between 2013 and 2018,
  • all provinces and territories experienced reductions in black carbon emissions between 2% to 45%
  • Alberta and Ontario experienced the largest reductions in emissions of 1.6 kt, respectively 

Black carbon emissions by province and territory, Canada, 2013 and 2018

Air pollutant emissions from transportation, off-road vehicles and mobile equipment

Transportation, off-road vehicles and mobile equipment are among the largest sources of air pollutants in Canada. Burning fossil fuels to power vehicles and engines causes emissions of many air pollutants. Air pollutants are responsible for the formation of fine particulate matter, ozone, smog and acid rain. They also adversely affect human health, the environment and the economy.

Key results

• In 2018, transportation, off-road vehicles and mobile equipment accounted for more than half of total national emissions of carbon monoxide (CO) and nitrogen oxides (NO_X) and 16% of total emissions of volatile organic compounds (VOCs)
• While also a source of emissions for fine particulate matter (PM_2.5), sulphur oxides (SO_X) and ammonia (NH₃), the sectors represented less than 3% of total national emissions of these other pollutants

Contribution of transportation, off-road vehicles and mobile equipment to total air pollutant emissions by transportation mode, Canada, 2018

How this indicator was calculated

Note: "Passenger cars and motorcycles" include cars powered by motor gasoline, diesel, liquefied petroleum gas and compressed natural gas engines as well as all types of motorcycles. "Passenger light trucks" include light-duty trucks powered by motor gasoline, diesel, liquefied petroleum gas and compressed natural gas engines. "Large trucks and buses" include heavy-duty trucks powered by motor gasoline, diesel, liquefied petroleum gas and compressed natural gas engines.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

The contribution of each transportation mode to emissions of different air pollutants is in large part explained by the mix of fuels used in these modes.

Large trucks and buses, and rail and marine rely predominantly on diesel fuel. Aviation relies on aviation turbo fuel. These transportation modes are the largest sources of NO_X transportation-related emissions accounting for 34% (596 kilotonnes [kt]) of total NO_X emissions.

Passenger cars and light trucks mostly use gasoline and are an important source of pollutants, especially in urban centres. In 2018, emissions from passenger cars, motorcycles and light trucks amounted to 1 337 kt of CO, 126 kt of NO_X and 115 kt of VOCs. These emissions represented 23%, 7% and 6% of all emissions of these pollutants respectively.

Other sources (mainly composed of off-road vehicles and equipment)^{Footnote 8} are also a significant source of pollution. Their combined emissions make up 23%, 11% and 7% of the total emissions of CO, NO_X and VOCs, respectively. Emissions mostly come from household use of gasoline- or diesel-powered recreational and lawn and garden equipment and from the operation of agricultural, construction and mining equipment.

The largest source of sulphur oxide (SO_X) emissions in the transportation sector is marine vessels. Emissions of SO_X from marine vessels decreased by 91% between 2014 and 2018 due to the introduction of more stringent regulations.

Changes in emissions from transportation, off-road vehicles and mobile equipment

Key results

• Between 1990 and 2018, total emissions of NO_X, CO and VOCs from transportation, off-road vehicles and mobile equipment decreased by 34%, 60% and 75%, respectively
• Since 2000, all pollutants demonstrated the same downward trend in their emissions level

Changes in emissions of key air pollutants from transportation, off-road vehicles and mobile equipment, Canada, 1990 to 2018

How this indicator was calculated

Note: Fine particulate matter, sulphur oxides and ammonia are not shown in the chart due to their low share (≤ 5%) of total emissions in 2018.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

Pollutant emissions have decreased despite economic and population growth as well as growth in transport activities for the period between 1990 and 2018. This decrease is mainly attributable to the adoption of new regulations that lead to the gradual introduction of technologies and clean fuel for vehicles.

Between 1990 and 2000, NO_X emissions increased by 24%. It includes the increase in emissions from light trucks (92%), large trucks and buses (44%) and marine transportation (34%). From 2000 to 2018, new regulations contributed to a decrease in emissions from light trucks (60%) and large trucks and buses (44%), while emissions from marine travel continued to increase by 2%. Emissions from air, marine and rail travel represented 17% of national emissions of NO_X in 2018.

Transportation emissions are influenced by a variety of factors. These include population and economic growth, volume of passenger and freight travel, vehicle type, emission control technologies, fuel efficiency and fuel type.

Air pollutant emissions from the electric utilities

Electricity generation produces a large share of total national sulphur oxides (SO_X) and nitrogen oxides (NO_X). SO_x and NO_X are mostly emitted from power plants burning fossil fuels such as coal and, to a lesser extent, natural gas and diesel. These air pollutants are responsible for the formation of fine particulate matter, ozone, smog and acid rain. They also adversely affect human health, the environment, and the economy.

Key results

• In 2018, electric utilities were the source of 27% and 7% of total national emissions of sulphur oxides (SO_X) and nitrogen oxides (NO_X)
• Most of the air pollutant emissions from electric utilities come from burning coal
• Electric utilities are also a source of carbon monoxide (CO), volatile organic compounds (VOCs), fine particulate matter (PM_2.5) and ammonia (NH₃) emissions. However, they account for less than 1% of the total national emissions of these pollutant

Contribution of electric utilities to total air pollutant emissions by fuel source, Canada, 2018

How this indicator was calculated

Note: Carbon monoxide, fine particulate matter, volatile organic compounds and ammonia are not shown in the chart due to their low share (≤ 1%) of total emissions in 2018. Excludes emissions from industries that generate electricity and heat as a supporting activity rather than as their primary purpose. "Other" fuel sources include waste material and other uncategorized sources of electricity generation.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

In 2018, 96% of SO_X and 71% of NO_X emissions from electric utilities came from burning coal.

While generating electricity by burning fossil fuels causes air pollutant emissions, the use of non-fossil energy sources, such as wind, nuclear and other renewable sources to generate electricity does not emit air pollutants. A large share of the electricity generated in Canada comes from sources that do not emit air pollutants:

• 60% of electricity comes from hydro
• 15% comes from nuclear power plants
• 7% comes from non-hydro renewable sources, such as wind, solar, tidal power and biomass^{Footnote 9} 

Changes in emissions from the electric utilities

Key results

• Emissions of SO_X and NO_X from electric utilities declined by 64% and 50%, respectively, between 1990 and 2018
• Most of that decline occurred from 2005 onward

Changes in emissions of key air pollutants from electric utilities, Canada, 1990 to 2018

How this indicator was calculated

Note: Carbon monoxide, fine particulate matter, volatile organic compounds and ammonia are not shown in the chart due to their low share (≤ 1%) of total emissions in 2018. Excludes emissions from industries that generate electricity and heat as a supporting activity rather than as their primary purpose.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

Between 1990 and 2018, emissions of NO_X and SO_X from electric utilities decreased by 50% and 64% respectively. The majority of the decline in emissions occurred from 2005 onwards. Between 2005 and 2018, the share of electricity that came from burning fossil fuels fell from 22% to 20%. This decline was mostly the result of a drop in electricity generation from coal power plants.^{Footnote 10}  The emissions reductions since 2005 are mainly due to:

• the change in the mix of energy sources used to generate electricity
• the introduction of regulations
• domestic and international agreements
• better removal technologies
• plant closures

Air pollutant emissions from the oil and gas industry

The oil and gas sector is an important contributor to air pollutant emissions.  Most emissions from the oil and gas sector come from activities such as exploration, drilling, production and field processing. Air pollutants are responsible for the formation of fine particulate matter (PM_2.5), ozone (O₃), smog and acid rain. They also adversely affect human health, the environment, and the economy. 

• In 2018, the oil and gas industry was a major contributor to total national emissions of volatile organic compounds (VOCs) (35%), sulphur oxides (SO_X) (32%), nitrogen oxides (NO_X) (27%) and carbon monoxide (CO) (10%)
• The oil and gas industry is also a source of emissions of fine particulate matter (PM_2.5) and ammonia (NH₃). However, in 2018, it made up less than 1% of the total emissions of these pollutants

Contribution of the oil and gas industry to total air pollutant emissions by activity type, Canada, 2018

How this indicator was calculated

Note: Fine particulate matter and ammonia are not shown in the chart due to their low share (≤ 1%) of total emissions in 2018.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

In 2018, the oil and gas industry was the sector contributing the most to total national emissions of VOCs. It was also the second-largest contributor to emissions of NO_X and SO_X, and the fourth-largest contributor to emissions of CO.

Most of emissions from the oil and gas industry came from upstream activities (exploration, drilling, production and field processing) compared to downstream activities (refining, storage and distribution). In 2018, 97% of VOC and NO_X, 95% of CO, and 82% of SO_X emissions from the oil and gas sector were from upstream activities.

Changes in emissions from the oil and gas industry

Key results

• Emissions of CO, NO_X and VOCs increased by 69%, 41% and 12%, respectively, between 1990 and 2018
• SO_X emissions decreased (51%) over that period

Changes in emissions of key air pollutants from the oil and gas industry, Canada, 1990 to 2018

How this indicator was calculated

Note: Fine particulate matter and ammonia are not shown in the chart due to their low share (≤ 1%) of total emissions in 2018.
Source: Environment and Climate Change Canada (2020) Air Pollutant Emissions Inventory.

The increases in CO, NO_X and VOC emissions were due to growth in oil and gas production (the upstream sector of the industry), as emissions from the downstream sector declined due to facility closures during that period. This increase is in part explained by the fact that crude oil production had more than doubled in Canada since 1990. The growth was mostly driven by a rapid increase in oil sands production. During the same period, production of natural gas from unconventional sources, such as those requiring the use of multi-stage fracturing techniques, also increased significantly.

The decrease in SO_X emissions was mostly the result of a decrease in emissions from bitumen and heavy oil upgrading and natural gas processing, attributed to better emission control technologies.

The Air Pollutant Emissions Inventory and the Black Carbon Emissions Inventory provide data and estimates on releases of air pollutants from human activities. These pollutants contribute to smog, acid rain, reduced air quality and climate change. Improvements to data and the analysis of trends are made periodically as new emission estimation methodologies are adopted and additional information is made available. Historical emissions are updated on the basis of these improvements.

Air Pollutant Emissions Inventory

The Air Pollutant Emissions Inventory fulfills many of Canada's international pollution levels reporting obligations.  Specifically, under the 1979 Convention on Long-range Transboundary Air Pollution, Canada is committed to submitting an annual inventory of emissions of key air pollutants to the United Nations Economic Commission for Europe. The inventory is a comprehensive assessment of 17 air pollutants,^{Footnote 13} combining emissions reported by facilities to the National Pollutant Release Inventory, with emissions estimated by Environment and Climate Change Canada. Estimates are developed using the latest estimation methods and are based on published statistics or other sources of information such as surveys and reports. The Air Pollutant Emission Inventory provides a comprehensive overview of pollutant emissions across Canada.

The national and provincial/territorial inventory data are current as of March 13, 2020, and cover the period from 1990 to 2018. Emissions data are compiled into a database for reporting approximately one year after data collection, validation and calculation have been completed. After this process is the interpretation of results and public reporting of the inventory. The Air pollutant emissions indicators are reported following the public release of the inventory data.

Black carbon emissions inventory

As a member of the Arctic Council, Canada committed under the Framework for Action on Enhanced Black Carbon and Methane Emissions Reductions to submit annual inventories of its black carbon emissions to the United Nations Economic Commission for Europe beginning in 2015. The Black Carbon Emissions Inventory is compiled using PM_2.5 emissions data from combustion-related sources from the Air Pollutant Emissions Inventory. Black carbon estimates are published separately from the Air Pollutant Emissions Inventory. The data are current as of March 13, 2020.

Black carbon is considered a short-lived climate pollutant, meaning it has a relatively short lifespan in the atmosphere (from a few days to a few weeks) compared to carbon dioxide (CO₂) (which can persist in the atmosphere for thousands of years) and other longer-lived greenhouse gases (GHGs). Although their life spans are short, short-lived climate pollutants are potent global warmers contributing to warming of the Earth's surface.^{Footnote 14}  Black carbon absorbs solar radiation 460 to 1 500 times more than CO₂.^{Footnote 15}  Short-lived climate pollutants, including black carbon, are important pollutants to consider when addressing climate change because they can respond relatively quickly to efforts to control their releases and thus impact near-term warming, which is particularly important in the Polar Regions, such as the Arctic.^{Footnote 16}  The Intergovernmental Panel on Climate Change (IPCC) special report on Global Warming states that reductions in short-lived climate pollutants are required to limit warming to a maximum of 1.5^oC, and Canada's Changing Climate Report flags short-lived climate pollutants as an important part of climate policy discussions.

National Pollutant Release Inventory

The National Pollutant Release Inventory is a database of pollutant releases (to air, water and land), disposals and transfers for recycling from industrial, commercial and institutional facilities. The data from these facilities is provided by the operators of the facilities as mandated by the Canadian Environmental Protection Act (the Act). Under the Act, owners or operators of facilities that manufacture, process or otherwise use or release one or more of the substances tracked by the inventory, and meet substance-specific reporting thresholds and other requirements, must report their pollutant releases, disposals and transfers annually to the department. The inventory data from 1994 to 2018 are current as of October 5, 2020.

Compilation of air pollutant emissions

The Air Pollutant Emissions Inventory is developed using 2 types of information:

• facility-reported data, consisting of emissions from relatively large industrial, commercial and institutional facilities
• in-house estimates, including diffuse sources and other sources that are too numerous to be accounted for individually, such as road and non-road vehicles, agricultural activities, construction and solvent use

The Air Pollutant Emissions Inventory is developed using many sources of information, procedures and emission estimation models. Emissions data reported by individual facilities to the department's National Pollutant Release Inventory are supplemented with documented, science-based estimation tools to quantify total emissions. Together, these data sources provide a comprehensive overview of pollutant emissions across Canada.

A compilation framework has been developed that makes use of the best available data, while ensuring that there is no double-counting or omissions. Additional information on the inventory compilation process is provided in Chapter 3 of the Air Pollutant Emissions Inventory Report.

Facility-reported emissions data

Facility-reported emissions data generally refers to any stationary sources that emit pollutants through stacks or other equipment at specific locations. The major source of facility-reported data is the National Pollutant Release Inventory.

Facility-reported data from the National Pollutant Release Inventory are used in the Air Pollutant Emissions Inventory without modifications, except when data quality issues are detected and not addressed during the quality control exercise. The National Pollutant Release Inventory reporting requirements and thresholds vary by pollutant and, in some cases, by industry. Details on these reporting requirements and thresholds are available on the National Pollutant Release Inventory website.

A distinction has been made between reporting facilities and non-reporting facilities. Reporting facilities meet the threshold required to report to the National Pollutant Release Inventory; while non-reporting facilities do not meet these thresholds due to their size or emission levels, and therefore are not required to report to the inventory. Some facilities may be required to report emissions on only certain pollutants. Therefore, emissions from the non-reporting facilities or of non-reported pollutants must be estimated in‑house to ensure complete coverage.

In-house emission estimates

In-house emission estimates are calculated with information such as production data and activity data, using various estimation methodologies and emission models. These emission estimates are at the national level rather than at any specific geographic locations. These include emissions from non-industrial, residential, commercial, transportation, and other sources, such as open burning, agricultural activities and construction operations. The Air Pollutant Emissions Inventory uses in-house estimates for the following emission sources:

• any residential, governmental, institutional, or commercial operation that does not report to the National Pollutant Release Inventory
• on-site solid waste disposal facilities
• motor vehicles, aircraft, vessels or other transportation equipment or devices
• other sources, such as open burning, agricultural activities and construction operations

In general, in-house emission estimates are calculated from activity data and emission factors.^{Footnote 17}  Activity data usually comprise statistical production or process data at the provincial, territorial or national level. This information is typically provided by provincial/territorial agencies, federal government departments, industry associations, etc. For each source category, activity data are combined with emission factors to produce provincial/territorial-level emission estimates.

The in-house emission estimate methodologies and emission models used in Canada are often based on those developed by the United States Environmental Protection Agency (U.S. EPA) and are adapted to reflect the Canadian climate, fuels, technologies and practices. Methods used in Canada's Air Pollutant Emissions Inventory are therefore generally consistent with those used in the United States or those recommended in the emission inventory guidebook.^{Footnote 18} 

The Air Pollutant Emissions Inventory reports air pollutant emissions from mobile sources such as on-road vehicles, off-road vehicles and engines. For the current edition of the Air Pollutant Emissions Inventory, an emissions estimation model developed by the U.S. EPA (MOVES) was used. The emissions for off-road vehicles and engines (such as graders, heavy trucks, outboard motors and lawnmowers) were estimated using the U.S. EPA's NONROAD emission estimation model (see "off-road vehicles and equipment" in Table A2-4 of Annex 2 of the Air Pollutant Emissions Inventory Report). The parameters in both models were modified to take into account variations in the Canadian vehicle fleet, emission control technologies, types of fuels, vehicle standards, and types of equipment engines and their application in various industries. The emission estimates for civil and international aviation, railways and navigation are estimated using detailed vehicle movement statistics coupled with fuel consumption, engine information, and emission rates by vehicle types.

Calculation of black carbon emissions

Emissions of black carbon are calculated by applying factors to estimate the fraction of black carbon in PM_2.5 emissions from combustion-related sources, with the exception of mobile sources, where models are used. The factors primarily come from the United States Environmental Protection Agency's SPECIATE database. SPECIATE is a repository of particulate matter speciation profiles of air pollution sources. Annex B of Canada's Black Carbon Emissions Inventory lists all the ratios used for each source.

Recalculations

Emission recalculation is an essential practice in the maintenance of an up-to-date air pollutant emissions inventory. The Air Pollutant Emissions Inventory is continuously updated with improved estimation methodologies, statistics and more recent and appropriate emission factors. As new information and data become available, previous estimates are updated and recalculated to ensure a consistent and comparable trend in emissions. Recalculations of previously reported emission estimates are common for both in-house estimates and facility-reported emission data. More information on recalculations is provided in Annex 3 of the Air Pollutant Emissions Inventory Report.

Emissions reconciliation

In several sectors, estimation of total emissions involves combining estimates provided by facilities with estimates developed in-house by the department. To prevent double counting of emissions and to confirm that the Air Pollutant Emissions Inventory includes all emissions, a comparison and reconciliation of emission estimates from various sources is performed for each pollutant, industry sector and geographical region, as appropriate. More information on the reconciliation process is provided in section 3.4 of the Air Pollutant Emissions Inventory Report.

Temporal coverage

Historical data are provided at the national level for the period from 1990 to 2018. For the regional indicators (provincial/territorial), emissions are presented for 1990 and 2018. Facility level emissions information are available from 2009 to 2018.

Air pollutant emissions by source classification

For the purpose of reporting the indicators, calculated emissions data from the Air Pollutant Emissions Inventory and Black Carbon Emissions Inventory are grouped into the following 13 sources:

1. agriculture (livestock, crop production and fertilizer)
2. building heating and energy generation
3. dust and fires
4. electric utilities
5. home firewood burning
6. incineration and waste
7. manufacturing
8. miscellaneous
9. off-road vehicles and mobile equipment
10. oil and gas industry
11. ore and mineral industries
12. paints and solvents
13. transportation (road, rail, air and marine)

Table 2 shows the allocation of air pollutant emission sources reported in the indicators compared with the sources and sectors reported by the Air Pollutant Emissions Inventory.