Canada’s Air Pollutant Emissions Inventory Report 2025: 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 several protocols, the most active being the Gothenburg, Heavy Metals, and Persistent Organic Pollutants (POPs) protocols. Canada has ratified all 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 three main types of air pollutants included in this report. The first are criteria air contaminants, which include emissions of particulate matter less than or equal to 2.5 microns in diameter (PM2.5), sulphur (expressed as sulphur dioxides or SO2),Footnote 1 nitrogen oxides (NOx), and VOCs. The second type is selected heavy metals: lead (Pb), cadmium (Cd), and mercury (Hg). Finally, the third type of air pollutants are POPs, which include dioxins and furans, hexachlorobenzene (HCB), and four types of polycyclic aromatic hydrocarbons (PAHs). 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 2 Canada's annual official submission to the UNECE comprises an air pollutant dataset submitted by February 15 and its accompanied report by March 15.
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 3 are supplemented with well-documented, science-based estimation tools and methodologies to quantify total emissions. Together, these data sources provide comprehensive coverage of air pollutant emissions across Canada. For more information on the APEI development, refer to Chapter 3.
Overview of Canada’s Air Pollution Emissions (1990 to 2023)
This edition of the Air Pollutant Emissions Inventory Report includes information on the most recent estimates of air pollutant emissions for 1990 to 2023.
The APEI indicates that 2023 emissions of 14 of the 17 reported air pollutants are decreasing compared to historical 1990 levels. A few air pollutant emission sources account for a significant portion of these trends as shown in Table ES-1.Footnote 4 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 34% (TPM) and 25% (PM10) since 1990. These increases are largely from dust emissions associated with transportation on unpaved roads as well as construction operations.
- Transportation on unpaved roads has increased approximately 77% in terms of vehicle kilometres travelled between 1990 and 2023.
- Capital expenditures on construction, which are used to calculate construction dust emissions and reflected in overall construction operations volume, have increased approximately 80% between 1990 and 2023.
- Emissions of NH3 in 2023 were 25% higher than 1990 levels.
- Ammonia emissions increased between 1990 and 2000 from 395 kt to 476 kt, then fluctuated between 449 kt and 498 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.
Table ES-1a: Canadian Air Pollutant Emission Trends (1990-2023)
| Air Pollutant | 1990 Total Emissions | 2023 Total Emissions | Change in total emissions (%) |
|---|---|---|---|
| TPM (Mt) | 20 | 27 | +34% |
| PM10 (Mt) | 6.5 | 8.2 | +25% |
| PM2.5 (Mt) | 1.6 | 1.4 | -15% |
| NH3 (kt) | 395 | 495 | +25% |
| SOx (kt) | 3,010 | 608 | -80% |
| Pb (t) | 1,023 | 93 | -91% |
| Cd (t) | 81 | 4.3 | -95% |
| Hg (t) | 34 | 3.1 | -91% |
| PAH (t) | 243 | 20 | -92% |
| NOx (Mt) | 2.2 | 1.2 | -45% |
| VOC (Mt) | 2.2 | 1.4 | -38% |
| CO (Mt) | 13 | 4.5 | -65% |
| D/F (gTEQ) | 233 | 77 | -67% |
| HCB (kg) | 39 | 4.8 | -88% |
Table ES-1b : Main Contributor to the Trends (1990-2023)
| Air Pollutant | Main contributor to the trend | Driver of the trend |
|---|---|---|
| TPM and PM10 | Dust | The increases in particulate matter emissions (TPM and PM10) are largely from dust emissions associated with transportation on unpaved roads as well as construction operations. Transportation on unpaved roads has increased in terms of vehicle kilometres travelled, and capital expenditures on construction, which are used to calculate construction dust emissions, have also increased. |
| PM2.5 and NH3 | Agriculture | Changes in farming practices related to the production of annual agricultural crops contributed to emission decreases of PM2.5, including reductions in areas under summer fallow and the adoption of conservation tillage practices. The increases in NH3 emissions are 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. |
| SOx, Pb, Cd, Hg and PAH | Ore and Mineral Industries | Non-Ferrous Refining and Smelting contributed to the decreases in emissions of SOx, Pb, Cd and Hg, in part owing to the closure of outdated smelters and implementation of pollution prevention measures. The Aluminium Industry contributed to the decreases in emissions of PAHs, in part owing to process improvements and to the progressive phase-out of old Söderberg aluminium production technologies. |
| NOx, VOC and CO | Transportation and Mobile Equipment | In the Transport and Mobile Equipment category, Heavy-Duty Diesel Vehicles contributed to the decreases in emissions of NOx, and Light-Duty Gasoline Trucks and Vehicles, to the decreases in VOCs and CO emissions. Despite a 168% increase in total vehicle kilometres travelled from the Heavy-Duty Diesel Vehicles and a 28% increase in the total fuel consumption of Light-Duty Gasoline Trucks and Vehicles, emissions have decreased due to improved fuel economy and implemented regulations that have effectively lowered NOx, CO and hydrocarbon emissions from engines. |
| D/F and HCB | Incineration and Waste | Waste Incineration contributed to the decrease in emissions of HCB and dioxins and furans, in part owing to improvements in incineration practices and technologies. |
When observing long-term emission trends, large-scale events can have a significant impact on a portion of the time series analyzed and should be considered. 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. Impacts of the pandemic, more pronounced in 2020, are now harder to distinguish in recent years, as most air pollutants have resumed their gradual downward trend of recent decades.
Between 2022 and 2023, 9 of the 17 pollutants have shown increases. The most significant ones are HCB (15 %), followed by TPM (5.8%), Cd (4.8 %), PM10 (4.5%) and Hg (4.2%). The PM increases are due to more kilometers travelled, while the other increases are due to variations in the facility-reported data or the activity data used to estimate emissions. Since most of these pollutants are now showing emission levels lower than the historical ones, and emissions totals are often driven mainly by only a few facilities, a small variation from one facility can be shown as a relatively large percentage variation. 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. In this respect, work is ongoing to attribute emissions closer to where they occur. Indeed, gridded maps of latest year emissions are now published on the Government of Canada Open Data Portal.Footnote 5 For each of the main sources of air pollutant emissions, the most significant pollutants have been selected and mapped on a 1 km grid (by ecodistrict for Agriculture). This represents the first iteration and will undergo continuous improvements. More information on gridded maps can be found in Chapter 3. Please contact ec.dirp.donnees-data.pird.ec@ec.gc.ca if additional details regarding the maps are needed.
Improvements to Canada’s Air Pollution Emission Estimates
Continuous improvement is considered good practice for air pollutants 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.
This year’s inventory includes numerous methodological improvements, the most significant one being in the Home Firewood Burning sector, resulting in overall downward recalculations in TPM, PM2.5, SOx, NOx, VOCs, and PAHs emissions, and upward recalculations in CO, 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 6 pursuant to the 1979 CLRTAP and its associated protocols. This edition of the Canada’s APEI indicates that all international commitments relative to air pollution emissions continue to be met. For more information on international commitments and a complete list of protocols under the CLRTAP, refer to Annex 4.
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 section 1.3.
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