Air pollutant emissions

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Sulphur oxide emissions by source

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

Key results

• Between 1990 and 2023, SO_X emissions decreased by 80% from 3 010 kilotonnes (kt) to 608 kt
• In 2023, 3 sources accounted for 93% (567 kt) of the total SO_X emissions: the oil and gas industry, the ore and mineral industries and electric utilities

Total sulphur oxide emissions by source, Canada, 1990 to 2023

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 1 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The interactive figures provide a dynamic and customizable format to explore the emissions.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, the oil and gas industry accounted for approximately 43% of total national SO_X emissions (264 kt). Electric utilities and ore and mineral industries followed with 22% (135 kt) and 28% (168 kt) of national emissions, respectively. For the ore and mineral industries, 35% (59 kt) of its SO_X emissions came from the non-ferrous refining and smelting industry.

The largest reduction in emissions between 1990 and 2023 was from ore and mineral industries with a reduction in emissions of approximately 1 316 kt. The largest driver of the reduction from this source was from the non-ferrous refining and smelting industry with a reduction of 1 207 kt over the period.

This significant decrease in SO_X emissions from 1990 to 2023 (80%) 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 4 major smelters in Manitoba, Ontario, Quebec and New Brunswick
• lower emissions from fossil-fuel-fired (such as, coal-fired) power-generating utilities due to better technologies and plant closures (for example, the phase-out of coal electricity generation in Ontario and Alberta)
• implementation of regulations on low-sulphur fuels^{Footnote 3 Footnote 4}     

More recently, between 2022 and 2023, SO_X emissions have declined due to decreases in emissions from the electric utilities industry of 19 kt (13%), largely driven by reduced use of coal power plants and increased use of cleaner fuels.

Sulphur oxide emissions by province and territory

Key results

• In 2023, Alberta and Saskatchewan accounted for 27% (164 kt) and 19% (117 kt) of national SO_X emissions
• Between 1990 and 2023
  • the largest reductions were observed in Ontario and Manitoba. Emissions in these provinces decreased by 1 028 kt (91%) and 507 kt (99.6%), respectively
  • Saskatchewan was the only province that had an increase in SO_X  emissions (15%, or 15 kt)

Sulphur oxide emissions by province and territory, Canada, 1990, 2005 and 2023

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 (2025) Air Pollutant Emissions Inventory.

Alberta had the highest SO_X emissions level in 2023, accounting for 27% (164 kt) of total national emissions. Emissions in the province mainly came from the oil and gas industry and electric utilities, combined, accounting for 94% (155 kt) of the emissions. Between 2005 and 2023, the province experienced a 64% decline in emissions (295 kt) with the oil and gas industry, notably reductions from natural gas processing and oil sands mining extraction and processing, accounting for a large part of the reductions since 2005. 

Saskatchewan was the second-highest emitter of SO_X in 2023, accounting for 19% (117 kt) of total national emissions. Emissions from electric utilities, specifically coal electric power generation, was the largest contributor to SO_X emissions in the province.  

Ontario ranked third, with 16% (96 kt) of total national emissions of SO_X; the ore and mineral industries sector was the most important source of emissions in the province in 2023.

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.^{Footnote 5} 

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.

Key results

• In 2023, 2 653 facilities across Canada reported SO_X emissions representing 90% of total national emissions. Of these facilities:
  • 2 206 facilities reported emissions under 25 tonnes (t)
  • 428 facilities reported emissions between 25 to 6 000 t
  • 19 facilities reported emissions of 6 000 t or more located in Quebec (5), Ontario (4), Alberta (4), Saskatchewan (3), Nova Scotia (2) and British Columbia (1)

Sulphur oxide emissions by reporting facilities, Canada, 2023

Source: Environment and Climate Change Canada (2025) 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 2023, NO_X emissions were 1 228 kilotonnes (kt); this is 45% lower than in 1990
• The oil and gas industry was the largest source of NO_X, representing 37% (452 kt) of total emissions in 2023

Total nitrogen oxide emissions by source, Canada, 1990 to 2023

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 1 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The interactive figures provide a dynamic and customizable format to explore the emissions.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

The oil and gas industry was the largest contributor of NO_X emissions between 1990 and 2023. Emissions of NO_X from this sector increased by 108 kt (31%) during that period. 

The transportation (road, rail, air, and marine) sector emitted the next largest proportion of NO_X emissions in 2023, representing 25% (303 kt) of total national emissions. This sector also experienced the largest decrease in emissions (592 kt or 66%) between 1990 and 2023.

The decline in NO_X emissions between 1990 and 2023 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)

More recently, between 2022 and 2023, NO_X emissions from transportation (road, rail, air and marine) sources have increased by 1 kt (0.4%), notably from domestic marine navigation. Likewise, the oil and gas industry saw NOx emissions increase by 8 kt (2%) between 2022 and 2023.

Nitrogen oxide emissions by province and territory

Key results

• In 2023, among provinces and territories, Alberta emitted the most NO_X. The province accounted for 42% (520 kt) of national emissions
• Between 1990 and 2023,
  • the largest reduction was observed in Ontario. Emissions decreased by 415 kt (70%) in the province
  • NO_X emissions increased in Northwest Territories and Nunavut by 61% (8 kt)^{Footnote 6}   

Nitrogen oxide emissions by province and territory, Canada, 1990, 2005 and 2023

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 (2025) Air Pollutant Emissions Inventory.

The oil and gas industry is an important source of NO_X emissions in Alberta, accounting for 68% (352 kt) of the province's NO_X emissions in 2023. The increasing contribution of this sector to the province's emissions between 1990 and 2023 was more than offset by emission reductions from the transport and electric utilities sectors.

British Columbia and Ontario contributed the second and third largest proportions of NO_X emissions in 2023, with British Columbia accounting for 14% (169 kt) and Ontario accounting for 14% (175 kt) of total national emissions, with transportation (road, rail, air and marine) being the most important source in both provinces followed by the oil and gas industry in British Columbia and off-road vehicles and mobile equipment in Ontario. However, Ontario experienced the largest decrease in emissions (415 kt) between 1990 and 2023 in large part due to emission reductions from transportation (road, rail, air and marine), electric utilities, manufacturing, ore and mineral industries and off-road vehicles and mobile equipment. In Ontario, the majority of total NO_X emission reductions occurred between 2005 and 2023 (363 kt).

Quebec ranked fourth, with 10% (119 kt) of total national emissions. Transportation (road, rail, air and marine) was the most important source of NO_X in this province. Quebec also experienced a large decrease in emissions (169 kt) between 2005 and 2023 mainly due to emission reductions from transportation (road, rail, air and marine).

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.

Key results

• In 2023, 3 917 facilities across Canada reported NO_X emissions representing 43% of total national emissions. Of these facilities: 
  • 2 452 facilities reported emissions under 50 tonnes (t)
  • 1 348 facilities reported emissions between 50 to 800 t
  • 117 facilities reported emissions of 800 t or more located in Alberta (43), Ontario (18), Quebec (14), British Columbia (9), Saskatchewan (8), Newfoundland and Labrador (7), Nova Scotia (6), New Brunswick (5), Northwest Territories (3), Nunavut (3), and Manitoba (1)

Nitrogen oxide emissions by reporting facilities, Canada, 2023

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

Navigate data using the interactive map

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 7}  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 2023, VOC emissions in Canada were 1 368 kilotonnes (kt); this is a 38% (832 kt) decrease from 1990 levels
• Since 1990, the oil and gas industry has been the highest contributor to VOC emissions. In 2023, the sector accounted for 40% (541 kt) of total emissions

Total volatile organic compound emissions by source, Canada, 1990 to 2023

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 and other miscellaneous sources. Consult Table 1 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The interactive figures provide a dynamic and customizable format to explore the emissions.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

Apart from the oil and gas industry, paints and solvents, and off-road vehicles and mobile equipment were also important sources of VOC emissions in 2023 contributing 20% (271 kt) and 9% (128 kt) of total emissions, respectively.

The largest emissions reduction between 1990 and 2023 was from transportation (road, rail, air and marine), with emissions reductions of 281 kt (81%). 

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 facility closures, decrease in production and improved emission controls
• lower levels of VOCs in products such as paints, solvents and cleaners

Compared to the previous year, VOC emissions increased by 1 kt (0.1%) in 2023. The largest increase was from the oil and gas industry 7 kt (1%), notably light medium crude oil production which accounted for just under half of the overall oil and gas increase (3.4 kt). 

Volatile organic compound emissions by province and territory

Key results

• Alberta emitted the highest proportion of VOCs in 2023, representing 35% (474 kt) of national emissions
• Between 1990 and 2023,
  • Ontario experienced the largest reduction in VOC emissions; emissions in the province decreased by 311 kt (53%)
  • Saskatchewan was the only province that experienced an increase in VOC emissions, with 16 kt (9%), primarily due to the oil and gas industry

Volatile organic compound emissions by province and territory, Canada, 1990, 2005 and 2023

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 (2025) Air Pollutant Emissions Inventory.

Alberta was the highest emitting province of VOCs in 2023 (474 kt), with the oil and gas industry as the main source, contributing 74% (349 kt) of the province's emissions

Ontario was the second-highest emitter of VOCs, accounting for 20% (279 kt) of total national emissions in 2023. The main emission sources are paints and solvents, off-road vehicles and mobile equipment, and manufacturing. Ontario also experienced the largest reduction in emissions, with 311 kt (53%) between 1990 and 2023, mainly as a result of emission reductions from manufacturing and transportation (road, rail, air and marine). The majority of the reductions in Ontario occurred between 2005 and 2023 (292 kt).

Saskatchewan was the third largest emitter, with 14% (193 kt) of total national emissions in 2023, where the oil and gas industry accounted for 73% of the emissions in that province.

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.

Key results

• In 2023, 4 755 facilities across Canada reported VOC emissions representing 17% of total national emissions. Of these facilities:
  • 3 099 facilities reported emissions under 15 tonnes (t)
  • 1 579 facilities reported emissions between 15 to 400 t
  • 77 facilities reported emissions of 400 t or more located in Alberta (27), Ontario (21), Saskatchewan (8), Quebec (8), Manitoba (4), New Brunswick (3), Newfoundland and Labrador (3), British Columbia (2) and Nova Scotia (1)

Volatile organic compound emissions by reporting facilities, Canada, 2023

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

Navigate data using the interactive map

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 2023, NH₃ emissions were 495 kilotonnes (kt), which is 25% higher than in 1990
• Agriculture (livestock, crop production and fertilizer) was the main source of NH₃ emissions in 2023. Emissions from this source accounted for more than 94% (463 kt) of total national emissions

Total ammonia emissions by source, Canada, 1990 to 2023

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 1 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The interactive figures provide a dynamic and customizable format to explore the emissions.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

Between 1990 and 2023, agriculture (livestock, crop production and fertilizer) experienced the largest increase (106 kt or 30%) in NH₃ emissions. It also remained the key source of NH₃ emissions throughout that period. Emissions from manufacturing (11 kt), other sources (14 kt) and transportation (road, rail, air and marine) (6 kt) combined represented 6% of national emissions in 2023.

The growth in NH₃ emissions from agriculture (livestock, crop production and fertilizer) between 1990 and 2023 is mainly due to the increased use of synthetic nitrogen fertilizers in crop production. Up to 2005, increasing livestock populations also added to the growth. However, from 2006 to 2011, livestock populations decreased and NH₃ emissions from that source have since declined slowly. More recently, emissions from crop production have been steadily increasing since 2006.^{Footnote 8} 

Ammonia emissions by province and territory

Key results

• In 2023, Alberta and Saskatchewan accounted for almost half (243 kt) of national NH₃ emissions
• Between 1990 and 2023,
  • Ontario experienced the largest emissions reduction with 13 kt (12%)
  • The largest increase in NH₃ emissions was in Saskatchewan with emissions more than doubling (a 60 kt increase) 
  • Alberta and Manitoba also increased in NH3 emissions by 39 kt and 18 kt, respectively

Ammonia emissions by province and territory, Canada, 1990, 2005 and 2023

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 (2025) Air Pollutant Emissions Inventory.

In 2023, Alberta emitted the most NH₃ of all the provinces and territories, accounting for 27% (135 kt) of total national emissions. Saskatchewan contributed the second-largest proportion  of NH₃, representing 22% (109 kt).

Ontario followed with 20% (98 kt) of total national emissions. Livestock farms and the application of fertilizers were the most important sources of NH₃ emissions in Ontario.

Virtually almost all of the increase in national emissions between 1990 and 2023 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.

Key results

• In 2023, 305 facilities across Canada reported NH₃ emissions representing 4% of total national emissions. Of these facilities:
  • 199 facilities reported emissions under 25 tonnes (t)
  • 98 facilities reported emissions between 25 to 400 t
  • 8 facilities rreported emissions of 400 t or more located in Alberta (5), British Columbia (1), Manitoba (1) and Saskatchewan (1)

Ammonia emissions by reporting facilities, Canada, 2023

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

Navigate data using the interactive map

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 2023,
  • CO emissions in Canada were 4 518 kilotonnes (kt), a decrease of 65% from 1990 levels
  • Off-road vehicles and mobile equipment was the largest source of CO emissions in Canada, representing 38% (1 713 kt) of total emissions
  • Transportation (road, rail, air and marine) was the second largest source, representing 22% (1 001 kt) of CO emissions in Canada

 Total carbon monoxide emissions by source, Canada, 1990 to 2023

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, manufacturing and other miscellaneous sources. Consult Table 1 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The interactive figures provide a dynamic and customizable format to explore the emissions.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, transportation, off-road vehicles and mobile equipment were the 2 most important sources of CO. These sources combined represented 60% (2 714 kt) of national emissions.

The largest reduction in emissions between 1990 and 2023 occurred in transportation (road, rail, air and marine) with an emission decrease of 5 104 kt (84%).

The decline in CO emissions between 1990 and 2023 was 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 2023, Quebec, Alberta and Ontario accounted for 70% (3 172 kt) of national CO emissions
• Between 1990 and 2023,
  • all provinces and territories experienced reductions in emissions
  • the largest reductions occurred in Ontario (2 637 kt or 73%), British Columbia (1 788 kt or 77%) and Quebec (1 339 kt or 53%)

Carbon monoxide emissions by province and territory, Canada, 1990, 2005 and 2023

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 (2025) Air Pollutant Emissions Inventory.

In 2023, Quebec emitted the most CO of all the provinces and territories, representing 26% (1 180 kt) of the total national emissions. Ore and mineral industries was the largest contributor to CO emissions in Quebec, representing 32% (376 kt) of the province’s total emissions. Within this sector, the aluminum industry accounted for 92% (346 kt) of the emissions.

The province of Alberta ranked second, with 23% (1 040 kt) of total national emissions in 2023, with 78% of those emissions from 2 sources; off-road vehicles and mobile equipment and the oil and gas industry.

Ontario, the third largest CO emitter, accounted for 21% (952 kt) of total national emissions. The off-road vehicles and mobile equipment sector accounted for 42% of the province's CO emissions.

The sharp decrease in emissions between 1990 and 2023 in all provinces and territories is mainly attributable to emission reductions from transportation (road, rail, air and marine), largely driven by improvements in fuel efficiency. Some of the largest reductions occurred between 2005 and 2023, notably for Ontario, with emissions decreasing by 1 519 kt (62%).

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.

Key results

• In 2023, 3 732 facilities across Canada reported CO emissions representing 19% of total national emissions. Of these facilities:  
  • 1 835 facilities reported emissions under 25 tonnes (t)
  • 1 812 facilities reported emissions between 25 to 1 000 t
  • 85 facilities reported emissions of 1 000 t or more located in Alberta (29), Ontario (18), Quebec (17), British Columbia (10), New Brunswick (6), Saskatchewan (4) and Newfoundland and Labrador (1)

Carbon monoxide emissions by reporting facilities, Canada, 2023

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

Navigate data using the interactive map

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.^{Footnote 9}   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 2023, PM_2.5 emissions were 1 370 kilotonnes (kt); this is 15% lower than in 1990
• Emissions from dust and fires (for example, road dust, dust from construction operations and prescribed burning^{Footnote 10} ) accounted for the majority of PM_2.5 emissions, reaching 63% (865 kt) of total national emissions in 2023
  • These emissions increased by 68% (352 kt) between 1990 and 2023, the majority of the increase coming from dust from construction operations, specifically non-residential construction, and unpaved roads

Total fine particulate matter emissions by source, Canada, 1990 to 2023

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 1 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category. The interactive figures provide a dynamic and customizable format to explore the emissions.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, 89% of PM_2.5 emissions came from open source emissions, such as dust and prescribed fires, and agriculture (livestock^{Footnote 11}  , crop production and fertilizer). PM_2.5 emissions does not include emissions from natural sources such as wildfires and vegetation. In general, these open source 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.  As such, exposure of PM_2.5 to most people in Canada is not driven by emissions from open sources, but rather from PM_2.5 that forms when pollutants react in the atmosphere. 

The remaining 11% of PM_2.5 emissions in 2023 came from home firewood burning (51 kt or 4%) and other sources, including:

• ore and mineral industries, representing 2% (31 kt) of the emissions
• manufacturing and miscellaneous sources, such as emissions from commercial cooking, each representing about 1% (15 kt and 16 kt) of emissions
• off-road vehicles and mobile equipment, representing about 1% (16 kt)
• the oil and gas industry, representing about 1% (13 kt)
• transportation (road, rail, air and marine), representing less than 1% (7 kt)
• other emissions (less than 1%; 7 kt) coming from building heating and energy generation, electric utilities, incineration and waste, and the use of paints and solvents

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

The decreases in PM_2.5 emissions between 1990 and 2023 are mainly attributable to emission reductions from agriculture (crop production) (327 kt or 48%), manufacturing (99 kt or 87%) and home firewood burning (50 kt or 50%). These reductions outweigh the increase in emissions from dust and fires (352 kt or 68%), specifically road dust and dust from construction operations, over the period. The adoption of conservation practices in crop production and the use of new fireplace inserts, furnaces and stoves that burn more efficiently to control home firewood burning emissions were the main drivers leading to the reductions.

Fine particulate matter emissions by province and territory

Key results

• In 2023, Saskatchewan and Alberta emitted the most PM_2.5, representing  51% (695 kt) of total national emissions
• Between 1990 and 2023,
  • the largest decrease was observed in Saskatchewan with 147 kt (29%)
  • PM_2.5 emissions increased by 6 kt (4%) in Quebec, 1 kt (50%) in Yukon and 4 kt (81%) in Northwest Territories and Nunavut

Fine particulate matter emissions by province and territory, Canada, 1990 and 2023

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 (2025) Air Pollutant Emissions Inventory.

In 2023, Saskatchewan was the highest emitting province of PM_2.5 emissions, accounting for 26% (359 kt) of total national emissions. Agriculture (specifically wind erosion) and dust and fires (specifically dust from unpaved roads) were the largest sources of PM_2.5 emissions in the province.

Alberta ranked second in 2023, with 25% (336 kt) of total national PM_2.5 emissions. Dust and fires (specifically dust from unpaved roads) were the largest sources, with agriculture (livestock, crop production and fertilizer) being the second-largest source of PM_2.5, specifically from wind erosion, tillage practices and harvesting.

Ontario ranked third, with 17% (228 kt), and Quebec ranked fourth with 11% (157 kt). For these 2 provinces, dust and fires were the largest source of emissions.

The exclusion of emissions from dust and fires and agriculture (livestock, crop production and fertilizer) provide a different breakdown of PM_2.5 emissions in each province and territory. With these emissions removed, Quebec becomes the largest emitting province of PM_2.5 in 2023, representing 31% (48 kt) of total emissions (156 kt); home firewood burning being the largest emitting source. Ontario ranks second with 24% (38 kt) of emissions, with home firewood burning and ore and mineral industries equally being the largest sources of emissions. Alberta and British Columbia rank third and fourth, representing 15% (24 kt) (the largest source being from the oil and gas industry) and 12% (19 kt) (the largest source being from the ore and mineral industries) of emissions. Between 1990 and 2023, with dust, fires and agriculture excluded, all of the provinces and territories experienced emissions reductions between 80% (British Columbia, with a 75 kt emission reduction; the primary source of emissions being from manufacturing) and 41% (Northwest Territories and Nunavut, with a 0.6 kt emission reduction; with off-road vehicles and mobile equipment being the largest sources of emissions).

Fine particulate matter 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 PM_2.5 emissions from individual facilities.

Key results

• In 2023, 4 921 facilities across Canada reported PM_2.5 emissions representing 4% of total national emissions. Of these facilities:  
  • 2 737 facilities reported emissions under 1 tonne (t)
  • 2 091 facilities reported emissions between 1 to 100 t
  • 93 facilities reported emissions of 100 t or more located in Quebec (22), British Columbia (18), Ontario (18), Alberta (16), Saskatchewan (9), Newfoundland and Labrador (5), New Brunswick (2), Manitoba (2), and Nunavut (1))

Fine particulate matter by reporting facilities, Canada, 2023

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

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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, contributing to climate warming and linked to adverse human health effects. Reductions in black carbon emissions have near-term climate and health and environmental benefits such as improving air quality, slowing climate warming, reducing snow and ice melts, increasing crop yields and reducing negative impacts to ecosystem health and human health.

Key results

• Emissions of black carbon were 22 kt in 2023, a decrease of 40% from 2013 
• In 2023, 3 sectors accounted for 76% of national black carbon emissions:
  • off-road vehicles and mobile equipment
  • home firewood burning
  • transportation (road, rail, air and marine) 

Total black carbon emissions by source, Canada, 2013 to 2023

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 1 in the Data sources and methods for more details. The interactive figures provide a dynamic and customizable format to explore the emissions.
Source: Environment and Climate Change Canada (2025) Canada's Black Carbon Emissions Inventory.

In 2023, off-road vehicles and mobile equipment (for example, lawn and garden equipment, recreational vehicles, excavators, graders) accounted for the largest proportion of total national emissions, representing 35% (8 kt) of emissions. Home firewood burning and transportation (road, rail, air and marine) were also large contributors, each representing 20% (4 kt) of total national emissions. The remaining emissions came from the oil and gas industry, building heating and energy generation and other sources (such as the ore and mineral industries).

Black carbon emissions by province and territory

Key results

• In 2023, 3 provinces, Alberta, Quebec and Ontario, accounted for 62% (13 kt) of total national black carbon emissions
• Between 2013 and 2023:
  • all provinces and territories experienced reductions in black carbon emissions between 18% to 68%, with the main sources of national reductions coming from the off-road vehicles and mobile equipment (44%, 5 937 kt), transportation (road, rail, air and marine) (56%, 5 685 kt) and home firewood burning (37%, 2 549 kt) sectors 
  • Alberta, Ontario and Quebec experienced the largest reductions in emissions with decreases of 2.8 kt each. For these 3 provinces, the reductions were mainly attributable to lower emissions from transportation (road, rail, air and marine) and off-road vehicles and mobile equipment

Black carbon emissions by province and territory, Canada, 2013 and 2023

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 upstream activities (i.e., exploration, drilling, production and field processing) and to a lesser extent from downstream activities (i.e., refining, storage and distribution). Air pollutants emitted by this sector contribute to 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. ^{Footnote 12} 

Key results

• In 2023, the oil and gas industry was a major contributor to total national emissions  of sulphur oxides (SO_X) (43%),  volatile organic compounds (VOCs) (40%), nitrogen oxides (NO_X) (37%) and carbon monoxide (CO) (12%)
• The oil and gas industry is also a source of emissions of fine particulate matter (PM_2.5) and ammonia (NH₃). However, in 2023, it made up only 1% of the respective total emissions of these pollutants

Contribution of the oil and gas industry to total air pollutant emissions by activity type, Canada, 2023

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 2023. In the oil and gas industry, upstream activities include exploration, drilling, production and field processing and downstream activities include refining, storage and distribution.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, the oil and gas industry was the largest contributor to the total national emissions of SO_X, VOCs and NO_X. It was also the third-largest contributor to emissions of CO.

Most emissions from the oil and gas industry came from upstream activities compared to downstream activities. In 2023, 98% of NH₃, 96% of VOC and NO_X, 94% of CO, 88% of PM_2.5 and 86% 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 SO_X and VOC emissions decreased 51% and 11% , respectively, between 1990 and 2023
• CO and NO_X increased by 61% and 31%, respectively, over that period

Changes in emissions of key air pollutants from the oil and gas industry, Canada, 1990 to 2023

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 2023.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

The increases in CO and NO_X emissions between 1990 and 2023 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.^{Footnote 13}  This increase is in part explained by the fact that crude oil production in Canada more than doubled since 1990. The growth was mostly driven by a rapid increase in oil sands production, particularly by in-situ oil sands extraction. 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 oil sands mining, extraction and upgrading, and natural gas production and processing, attributed to better emission control technologies. 

For VOCs, the recent decline was partly due to reductions in light/medium crude oil production and petroleum refining, storage and distribution. The decrease in VOC emissions is also driven by reduced venting emissions from crude oil production since 2014 (over this period, operators took measures to conserve gas under provincial directives, even prior to the implementation of federal and provincial regulations). In addition, federal and provincial regulations to reduce fugitive emissions from the sector came into effect in 2020, contributing further to the decline.

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. These air pollutants lead to the formation of fine particulate matter, ozone, smog and acid rain. These pollutants and resulting impacts also adversely affect human health, the environment and the economy.

Key results

• In 2023, transportation, off-road vehicles and mobile equipment accounted for more than half (60%) of total national emissions of carbon monoxide (CO), 38% of nitrogen oxides (NO_X) and 14% of total emissions of volatile organic compounds (VOCs)
  • While also a source of emissions for fine particulate matter (PM_2.5), ammonia (NH₃) and sulphur oxides (SO_X), the sectors represented less than 2% of total national emissions, respectively

Contribution of transportation, off-road vehicles and mobile equipment to total air pollutant emissions by transportation mode, Canada, 2023

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 (2025) 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 travel rely predominantly on diesel fuel. Aviation relies on turbo aviation fuel. These transportation modes are the largest sources of NO_X transportation-related emissions accounting for 22% (268 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 2023, emissions from passenger cars, motorcycles and light trucks amounted to 834 kt of CO, 34 kt of NO_X and 48 kt of VOCs. These emissions represented 18%, 3% and 4% of all emissions of these pollutants respectively.

Off-road vehicles and equipment^{Footnote 14}  are also a significant source of pollution. Their combined emissions make up 38%, 13% and 9% 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. In 2023, commercial equipment use produced higher emissions of NO_X, PM_2.5, SO_X, and NH₃ compared to recreational and lawn and garden equipment use. However, emissions of CO and VOCs were greater from recreational and lawn and garden equipment use than from commercial use of equipment.

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

Key results

• Between 1990 and 2023, total emissions of NO_X, VOCs and CO from transportation, off-road vehicles and mobile equipment decreased by 63%, 69% and 72%, respectively
• Since 2000, all 3 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 2023

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 2023.
Source: Environment and Climate Change Canada (2025) 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 2023. This decrease is mainly attributable to the adoption of new regulations that lead to the gradual introduction of emission control technologies and clean fuel for vehicles. 

Between 1990 and 2000, NO_X emissions increased by 23%. It includes the increase in emissions from light trucks (116%), large trucks and buses (19%) and marine and air transportation (17 and 19%), which can be linked to economic and population growth during that time. From 2000 to 2023, new regulations contributed to a decrease in NO_X emissions (33%, 71 kt) from light trucks (91%), large trucks and buses (72%) and emissions from rail travel (52%).

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, transportation infrastructure, fuel efficiency and fuel type.

Air pollutant emissions from the electric utilities

Electricity generation produces 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 contribute to 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 2023, electric utilities were the source of 22% and 7% of total national emissions of sulphur oxides (SO_X) and nitrogen oxides (NO_X), respectively
• 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 pollutants

Contribution of electric utilities to total air pollutant emissions by fuel source, Canada, 2023

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 2023. The indicator excludes emissions from industries that generate electricity and heat as a supporting activity rather than as their primary purpose. "Other sources" include fuel sources such as waste material and other uncategorized sources of electricity generation.
Source: Environment and Climate Change Canada (2025) Air Pollutant Emissions Inventory.

In 2023, 92% of SO_X and 51% 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 hydroelectric, 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 directly emit air pollutants:

• 62% of electricity comes from hydro
• 13% comes from nuclear power plants
• 8% comes from non-hydroelectric renewable sources, such as wind, solar, tidal power and biomass^{Footnote 15} 

Changes in emissions from electric utilities

Key results

• Emissions of SO_X and NO_X from electric utilities declined by 78% and 65%, respectively, between 1990 and 2023
• Most of that decline occurred from 2005 onward

Changes in emissions of key air pollutants from electric utilities, Canada, 1990 to 2023

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 2023. 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 (2025) Air Pollutant Emissions Inventory.

The majority of the decline in SO_X and NO_X emissions between 1990 and 2023 occurred from 2005 onwards. Between 2005 and 2023, the share of electricity that came from burning fossil fuels fell from 25% to 18%. This decrease was mostly the result of a reduction in the use of coal power plants for electricity generation.^{Footnote 16}  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 targeting air pollutants and greenhouse gases emitted from electricity generation facilities
• domestic and international agreements
• better pollutant removal technologies used in smokestacks
• power plant closures

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 methods for trend analysis 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 has 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 20}  combining emissions reported by facilities to the National Pollutant Release Inventory with emissions of all other sources 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 14, 2025, and cover the period from 1990 to 2023. 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 (2015) to submit periodic inventories of its black carbon emissions to the Arctic Council Secretariat. Canada already voluntarily reports black carbon emissions to the United Nations Economic Commission for Europe as a Party to the Gothenburg Protocol, which was amended in 2012 to add fine particulate matter. 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 14, 2025.

Black carbon is a short-lived climate pollutant, (SLCP), meaning it contributes to warming but 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 hundreds to thousands of years) and other longer-lived greenhouse gases (GHGs). Although their life spans are short, SLCPs are potent contributors to warming of the Earth's surface.^{Footnote 21}   When black carbon deposits on snow and ice, it darkens the surface, accelerating heating and melting, creating a warming impact that is particularly strong in the Arctic and other snow covered areas (including glaciers).^{Footnote 22}  Reducing emissions of SLCPs, including black carbon, help slow near-term warming – the impacts of reductions are seen quickly because SLCPs have such short lifespans in the atmosphere. 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 because mitigation can slow global temperature warming and improve air quality.

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 1993 to 2023 are current as of November 27, 2025.

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, provincial and territorial levels, 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 23}  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 24} 

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 A2-1 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 some exceptions, for example, the 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^{Footnote 25}  of air pollution sources. The ratios used for each source are available on the Government of Canada’s Open Data Portal. More information on black carbon emission estimation methods can be found in Chapter 3 of Canada’s Black Carbon Inventory Report.

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 2023, except for black carbon, which covers the period from 2013 to 2023. For the regional indicators (provincial/territorial), emissions are presented for 1990 (2013 for black carbon) and 2023. Facility level emissions information are available from 2011 to 2023.

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 1 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.

Note: ^[A] Includes electric power generation from combustion of waste materials by utilities and by industry for commercial sale and/or private use. ^[B] Includes human respiration, perspiration and dental amalgams.

For display purposes, smaller emitting sources are sometimes grouped together under the title Other sources in the charts of air pollutant emissions by source. The names of the sources grouped as such are listed in the notes of each chart.

Sectoral indicators

Sectoral indicators on air pollutant emissions from transportation, off-road vehicles and mobile equipment, electric utilities and the oil and gas industry provide additional analysis on the largest sources of Canada's air pollutant emissions. These indicators also rely on calculated emissions data from the Air Pollutant Emissions Inventory.

These indicators are provided at the national level. They identify the contribution of each sector to the national emissions of air pollutants for the year 2023. They also provide information about emissions of selected pollutants, by sector, for the period from 1990 to 2023.

Tables 2 through 4 below show the alignment of air pollutant emission sources reported in the Air pollutant emissions indicators compared with those reported by the sectoral indicators.

Note: ^[A] Includes electric power generation from combustion of waste materials by utilities and by industry for commercial sale and/or private use.