Canada’s Air Pollutant Emissions Inventory Report 2024: Executive Summary

Canada’s Air Pollutant Emissions Inventory (APEI) is a comprehensive inventory of anthropogenic emissions of 17 air pollutants at the national, provincial and territorial levels. This inventory fulfills Canada’s international reporting obligations under the 1979 Convention on Long-range Transboundary Air Pollution (CLRTAP or Air Convention) of the United Nations Economic Commission for Europe (UNECE). The Air Convention has been supplemented by number of protocols, the most active being the Gothenburg, Heavy Metals, and Persistent Organic Pollutants (POPs) protocols. Canada has ratified all of the protocols except for the 1991 Protocol on Volatile Organic Compounds (VOCs). The requirements under that Protocol are obsolete, given that Canada now has commitments on VOCs under the Gothenburg Protocol. The Air Convention protocols aim to reduce emissions of particulate matter less than or equal to 2.5 microns in diameter (PM_2.5), sulphur (expressed as sulphur dioxides or SO₂), nitrogen oxides (NO_x), VOCs, lead (Pb), cadmium (Cd), mercury (Hg), dioxins and furans, and other POPs: polycyclic aromatic hydrocarbons (PAHs), which include four types, and hexachlorobenzene (HCB). The APEI also reports emissions of additional air pollutants including total particulate matter (TPM), particulate matter less than or equal to 10 microns in diameter (PM₁₀), carbon monoxide (CO) and ammonia (NH₃).^{Footnote 1}

In addition, the APEI supports monitoring and reporting obligations under the Canada-U.S. Air Quality Agreement and the development of air quality management strategies, policies and regulations. It also provides data for air quality forecasting and informs Canadians about pollutants that affect their health and the environment.

The APEI is compiled from many different data sources. Emission data reported by individual facilities to Environment and Climate Change Canada’s (ECCC) National Pollutant Release Inventory (NPRI)^{Footnote 2} are supplemented with well-documented, science-based estimation tools and methodologies to quantify total emissions. Together, these data sources provide a comprehensive coverage of air pollutant emissions across Canada. For more information on the APEI development, refer to Chapter 3.

Canada's annual official submission to the UNECE comprises an air pollutant dataset submitted by February 15 and its accompanied report by March 15. This edition of the Air Pollutant Emissions Inventory Report includes information on the most recent estimates of air pollutant emissions for 1990 to 2022.

Canada’s Air Pollution Emission Trends (1990 to 2022)

The APEI indicates that emissions of 14 of the 17 reported air pollutants are decreasing compared to historical levels. In 2022, notable examples include decreases of 95% of Cd emissions, 91% of Hg emissions, 88% of Pb emissions, 78% of SO_x emissions and 65% of CO emissions compared to 1990 emission levels.^{Footnote 3}  A few key sources of air pollutants account for a significant portion of these downward trends. In particular:

• Non-Ferrous Refining and Smelting is a major contributor to emissions of Hg, Cd, SO_x, and Pb; emissions of these pollutants from this source have decreased by almost 100%, 98%, 94% and 89%, respectively, in part owing to the closure of outdated smelters and implementation of pollution prevention measures.
• Coal-fired electric power generation is a major contributor to emissions of HCB, Hg and SO_x; emissions of these pollutants from this source have decreased by 98%, 76% and 72%, respectively, as emission control equipment was adopted on some older units, and more recently, as coal-fired power plants have closed down and have been replaced by lower-emission sources such as natural gas power plants.
• Light-Duty Gasoline Trucks and Vehicles are major contributors to emissions of NO_x and PAHs; emissions of these pollutants from these sources have decreased by 90% and 83%, respectively.
  • Despite a 66% increase in total vehicle kilometres travelled (VKT) from these vehicle types, emissions have decreased primarily due to improved fuel economy and implemented regulations that have effectively lowered NO_x and hydrocarbon emissions from engines.
• Waste Incineration is a major contributor to emissions of HCB and dioxins and furans; emissions of these pollutants from this source have decreased by 95% and 84%, respectively, in part owing to improvements in incineration practices and technologies.
• The combustion of gasoline^{Footnote 4}  in the Transportation and Mobile Equipment source category is a major contributor to emissions of CO and VOCs; emissions of these pollutants from this source have decreased by 72% each.
  • Despite a 24% increase in the total fuel consumption of on-road Light-Duty Gasoline Trucks and Vehicles and a 36% increase in the total fuel consumption of off-road gasoline engines, emissions have decreased primarily due to implemented regulations that have effectively lowered CO and hydrocarbon emissions from engines.
• The activities associated with the production of annual agricultural crops are a major contributor to emissions of PM_2.5; emissions from this source have decreased by 48%, in part owing to reductions in areas under summer fallow and the adoption of conservation tillage practices.

Despite significant decreases in emissions of most pollutants, emissions of a few air pollutants have increased since 1990:

• Particulate matter emissions have risen gradually by 18% (TPM) and 13% (PM₁₀) since 1990. These increases are largely from dust emissions associated with transportation on unpaved roads as well as construction operations.
• Emissions of NH₃ in 2022 were 22% higher than 1990 levels.
  • Ammonia emissions increased between 1990 and 2000 from 395 kt to 476 kt, then oscillated between 449 kt and 499 kt.
  • This upward trend is primarily driven by increases in livestock populations in the first half of the time series in combination with continual increases in the use of inorganic nitrogen fertilizer throughout the monitoring period

Additional information on air pollutant emission trends can be found in Chapter 2.

Irrespective of the downward trends observed in Canadian emissions, air quality issues may still arise when emission sources are spatially concentrated. While the APEI provides valuable information on emissions within Canada, it does not distinguish localized sources of emissions within the provincial and territorial level aggregations.

Recent Observed Changes in Canada’s Air Pollution Emissions (2019 to 2022)

When observing long-term emission trends, large-scale events can have a significant impact on a portion of the time series analyzed and must be taken into account. The years 2020 and 2021 were marked by the COVID-19 pandemic. This coincides with notable observed emission decreases between 2019 and 2020 for almost all pollutants except for NH_3. In 2021, the second year of the pandemic, most of the pollutant emissions increased compared to 2020 levels, mainly due to the recovery of transportation (air, road and marine) and production in some industrial sectors, but the majority of pollutants remained below their 2019 pre-pandemic levels.

The first year following the end of pandemic-related restrictions and closures, 2022, has shown decreases in eight pollutants compared to 2021 (CO, Cd, dioxins and furans, HCB, Hg, NH₃, NO_x, and PM_2.5). In contrast, emissions of nine pollutants (Pb, TPM, PM₁₀, PAHs, SO_x and VOC) increased between 2021 and 2022. For all pollutants except NH₃ and Pb, emissions in 2022 remained below 2019 pre-pandemic levels. Impacts of the pandemic, more pronounced in 2020, are now harder to distinguish in 2022, as most air pollutants have resumed their gradual downward trend of recent decades.

The categories with major emission changes between 2019 and 2022 are most notably:

• Transportation and Mobile Equipment showed decreases of VOCs (-46 kt or -19%), CO (-412 kt or -13%) and NO_x (-63 kt or -10%) over this period.
  • These reductions are mostly due to a decrease in VKT between 2019 and 2020 in the Light-Duty Gasoline Trucks and Vehicles categories; between 2020 and 2022, VKT increased but were still below 2019 pre-pandemic levels.
  • A similar change is noted from Unpaved Road Dust, also linked to VKT, with a greater emission decrease between 2019 and 2020 followed by an increase in 2021, resulting in an overall decrease for PM_2.5 (-19 kt or -4.5%) between 2019 and 2022.
• The Oil and Gas Industry contributed to emission decreases of VOCs (-83 kt or -14%) and NO_x (-25 kt or -5.4%), and an increase in SO_x emissions (7.7 kt or 2.9%) over this period.
  • The VOC reductions result from decreases in venting and fugitive equipment leaks at oil and natural gas production and processing facilities.
  • The overall decreases in NO_x can be explained in part by sustained reductions in fuel combustion emissions following a drop in total crude oil and natural gas production in 2020, along with decreases in the Petroleum Refining subsector that are mainly due to the closure of the Come-By-Chance refinery in Newfoundland and Labrador.
  • The overall increase in SO_x emissions is due to increases in crude bitumen production in 2021 and 2022, as well as increased flaring at natural gas production and processing facilities.
• Coal electric power generation saw emission decreases of SO_x (-55 kt or -28%) and Hg (-113 kg or -20%) over this period, between 2019 and 2020
• Ore and Mineral Industries emissions of Cd (-2.4 t or -51%) and HCB (-1.4 kg or -31%) decreased; in contrast, Pb emissions increased by 6.2 t or 6.2%, over this period.
  • HCB and Cd emissions from the Non-Ferrous Refining and Smelting Industry decreased (-2.3 kg or -84%, and -2.3 t or -57%, respectively) between 2019 and 2022 due to the permanent closure of a non-ferrous metal smelter in December of 2019.
  • Between 2019 and 2022, Pb emissions from the Non-Ferrous Refining and Smelting Industry increased significantly (9.0 t or 10%) mainly due to normal operational variations and differences in sampling results at a single facility that accounts for 74 to 93% of emissions from this industry, directly impacting observed changes.

Improvements to Canada’s Air Pollution Emission Estimates

Continuous improvement is considered good practice for air pollutant inventory preparation. ECCC consults and works with key federal, provincial and territorial partners, along with industry stakeholders, research centres and consultants, on an ongoing basis to improve the quality of the information used to compile the APEI. As new information and data become available and more accurate methods are developed, previous estimates are updated to provide a consistent and comparable trend in emissions and removals.

This year’s inventory includes significant methodological improvements in the Dust Construction Operations and Waste Incineration sectors, resulting in overall downward recalculations in PM_2.5 and HCB emissions, respectively, compared to the last APEI edition. For more information on recalculations, refer to Annex 3.

Canada’s Air Pollution Emissions Relative to International Commitments

Canada reports on atmospheric emissions of air pollutants to the UNECE through the European Monitoring and Evaluation Programme (EMEP) Centre on Emission Inventories and Projections (CEIP)^{Footnote 5}  pursuant to the 1979 CLRTAP and its associated protocols. This edition of the Air Pollutant Emissions Inventory Report indicates that:

• Emissions of PM_2.5 were 1.3 megatonnes (Mt) in 2022.
  • Emissions of PM_2.5 decreased from most sources with the notable exceptions of dust sources (not from combustion) such as construction operations and roads; Canada’s emission reduction commitment for PM_2.5 excludes these two sources along with agricultural crop production.
  • In line with Canada’s commitment, PM_2.5 emissions in 2022 were 31% lower than 2005 levels; therefore, Canada continues to meet its commitment to reduce emissions of PM_2.5 by 25% from 2005 levels by 2020 and beyond, as per the amended Gothenburg Protocol.
• Emissions of SO_x were 0.7 Mt in 2022, which is 55% below the 2010 emission ceiling under the 1999 Gothenburg Protocol and 69% below 2005 levels; therefore, Canada continues to meet its commitment to reduce emissions of SO_x by 55% from 2005 levels by 2020 and beyond, as per the amended Gothenburg Protocol.
• Emissions of NO_x were 1.3 Mt in 2022, which is 42% below the 2010 emission ceiling under the 1999 Gothenburg Protocol and 43% below 2005 levels; therefore, Canada continues to meet its commitment to reduce emissions of NO_x by 35% from 2005 levels by 2020 and beyond, as per the amended Gothenburg Protocol.
• Emissions of non-methane VOCs (NMVOCs) were 1.4 Mt in 2022, which is 33% below the 2010 emission ceiling under the 1999 Gothenburg Protocol and 39% below 2005 levels; therefore, Canada continues to meet its commitment to reduce emissions of NMVOCs by 20% from 2005 levels by 2020 and beyond, as per the amended Gothenburg Protocol.
• Emissions of Cd, Hg and Pb in 2022 were 90%, 82% and 75% respectively below the ceilings established under the 1998 Aarhus Protocol on Heavy Metals.
• Emissions of all POPs in 2022 were below the ceilings established under the 1998 Aarhus Protocol on Persistent Organic Pollutants, including HCB (89% below), the four species of PAHs (81% below), and dioxins and furans (65% below).

Canada’s Air Emissions Regulations and Non-Regulatory Measures

Downward trends in emissions of air pollutants reflect the ongoing implementation of a wide range of regulatory and non-regulatory instruments that aim to reduce or eliminate pollutants to improve and maintain air quality in Canada. Regulations related to the 17 APEI pollutants are under the Canadian Environmental Protection Act, 1999 (CEPA 1999).

Several greenhouse gas regulations are also expected to achieve significant co-benefit reductions in air pollutants, for example the Regulations Respecting Reduction in the Release of Methane and Certain Volatile Organic Compounds (Upstream Oil and Gas Sector).

Non-regulatory instruments include guidelines, as well as codes of practice, performance agreements and pollution prevention planning notices for various sectors. More information on Canada’s air emissions Regulations and non-regulatory measures, including a list of Regulations related to APEI pollutants, can be found in Chapter 1.3.