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 (PM2.5), sulphur (expressed as sulphur dioxides or SO2), nitrogen oxides (NOx), 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 SOx 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:

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

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 NH3. 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, NOx, and PM2.5). In contrast, emissions of nine pollutants (Pb, TPM, PM10, PAHs, SOx 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:

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 PM2.5 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:

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.

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