Canada’s Air Pollutant Emissions Inventory Report 2023: 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 serves many purposes: it fulfills Canada’s international reporting obligations under the 1979 Convention on Long-range Transboundary Air Pollution (CLRTAP) and the associated protocols ratified by Canada for the reduction of emissions of sulphur (expressed as sulphur dioxides or SO2), nitrogen oxides (NOx), fine particulate matter (PM2.5), cadmium (Cd), lead (Pb), mercury (Hg), volatile organic compounds (VOCs), dioxins and furans, and other persistent organic pollutants (POPs). The APEI also reports emissions of additional air pollutants including ammonia (NH3)Footnote 1 , carbon monoxide (CO), coarse particulate matter (PM10) and total particulate matter (TPM). 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, 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) 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. 

Recent observed changes in Canada's air pollution emissions (2019 to 2021)

The most recent years for which data are available for this report, 2020 and 2021, were marked by the COVID-19 pandemic. This coincides with observed emission decreases between the years 2019 and 2020 for almost all pollutants with the exception of NH3. Between 2020 and 2021, most of the pollutant emissions increased, but remained below their 2019 pre-pandemic levels, except for NH3 and hexachlorobenzene (HCB) that exceeded their 2019 emission levels in 2021. In contrast to these increases, SOx, Pb and polycyclic aromatic hydrocarbons (PAHs) emissions continued to decrease between 2020-2021, while VOC emissions remained stable. The categories that were major contributors to emission changes between 2019 and 2020 are similar to those observed between 2019 and 2021 occurring in numerous source categories, most notably:Footnote 2

Canada’s air pollution emission trends (1990 to 2021) 

This edition of the Air Pollutant Emissions Inventory Report summarizes the most recent estimates of air pollutant emissions for 1990 to 2021, as of February 2023. The inventory indicates that emissions of 14 of the 17 reported air pollutants are decreasing compared to historical levels, and a few key sources of pollutants account for a significant portion of the downward trends. In particular:

Despite significant decreases in emissions of most pollutants, since 2005, emissions of particulate matter have risen by 38% (TPM), 33% (PM10) and 18% (PM2.5). These increases are largely from dust emissions associated with transportation on unpaved roads as well as construction operations. Another exception to the general downward trends is the steady increase in emissions of NH3, which in 2021 were 25% above 1990 levels, and 1% above 2005 levels. The upward trend in NH3 emissions is primarily driven by the use of inorganic nitrogen fertilizer.

Irrespective of the downward trends observed in Canadian emissions, air quality issues may still arise when emissions 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.

Canada’s air pollution emissions relative to international commitments

Canada reports on atmospheric emissions of air pollutants to the United Nations Economic Commission for Europe (UNECE) through the European Monitoring and Evaluation Programme (EMEP) Centre on Emission Inventories and Projections (CEIP) 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 in order 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). 

A number of 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/or 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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