Canada’s Air Pollutant Emissions Inventory Report 2022: chapter 2

2020 Emissions and trends

This chapter describes the main sources and sectors contributing to the emissions of each pollutant and their historical trends. A description of source categories, sectors and sub-sectors is provided in Chapter 1 Table 1–1.

The contribution of each source category to total emissions of air pollutants for 2020 varies by pollutant (Table 2–1), ^{Footnote 1}  for example.

• Dust, largely from construction operations and unpaved roads, accounts for 62% of emissions of particulate matter less than or equal to 2.5 microns (PM_2.5).
• Agriculture accounts for most ammonia (NH₃) emissions (94%).
• Incineration and Waste accounts for a significant proportion of hexachlorobenzene (HCB), and dioxins and furans (D/F) emissions (61% each).
• Ore and Mineral Industries accounts for the largest proportion of lead (Pb) (83%), cadmium (Cd) (51%) and mercury (Hg) (37%) emissions.
• Transportation and Mobile Equipment is the largest emitter of carbon monoxide (CO) (62%) and nitrogen oxides (NO_x) (47%).
• Oil and Gas Industry is the largest emitter of sulphur oxides (SO_x) (38%) and volatile organic compounds (VOCs) (36%).
• Commercial/Residential/Institutional is a particularly significant source of polycyclic aromatic hydrocarbons (PAHs) (84%).

The most recent year for which data are available for this report, the year 2020, was 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. These decreases occurred in numerous source categories, most notably:

• Transportation and Mobile Equipment showed decreases of NO_x (-92 kt or -12%), VOCs (-33 kt or -12%) and CO (-272 kt or -8.6%). 
  • These reductions are mostly due to a decrease in the vehicle kilometres traveled (VKT) in the Light-Duty Gasoline Vehicles and Trucks categories. 
  • The decrease in VKT can also be linked to the Unpaved Roads Dust source emission reduction for PM2.5 (-58 kt or -14%).
•  The Oil and Gas Industry contributed to the decrease in SO_x (-26 kt or -10%) and VOCs emissions (-83 kt or -13%). 
  • The reductions in SO_x can be explained in part by a 5% reduction in total crude oil production and a 2% reduction in natural gas production 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 VOC reductions result from decreases in venting and leaks at oil and natural gas production and processing facilities.

• Coal electric power generation saw emission decreases of SO_x (-37 kt or -19%) and Hg (-95 kg or 16%) attributed to a decrease in coal consumption.
• Decreases in Ore and Mineral Industries emissions of Pb (-6.6 t or -6.4%), Cd (-2.2 t or -51%) and HCB (-1.8 kg or -40%) are in part due to the permanent closure of a non-ferrous metal smelter in December 2019.

This edition of the Air Pollutant Emissions Inventory Report summarizes the most recent estimates of air pollutant emissions for 1990 to 2020, as of February 2022. 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:

• The Non-Ferrous Refining and Smelting Industry sector is a major contributor to emissions of Pb, SO_x, Cd and Hg; emissions of these pollutants from this source have decreased by 91%, 93%, 98% and 99%, respectively, over this time period, in part owing to closure of outdated smelters and implementation of pollution prevention measures.
• Home Firewood Burning is a major contributor to emissions of PM_2.5, VOCs, CO and PAHs; emissions of these pollutants from this source have decreased by 43%, 39%, 34% and 29% respectively, over this time period, owing to a 28% reduction in wood consumption and the adoption of more efficient wood combustion equipment.
• Coal-fired electric power generation is a major contributor to emissions of SO_x, Hg and HCB; emissions of these pollutants from this source have decreased by 69%, 75% and 98%, respectively, over this time period 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 have each decreased by 69% from these sources, over this time period.
  • The decrease in emissions is despite a 72% increase in the number of these vehicles on the road, and is due to regulations that have effectively decreased sulphur levels in fuels and lowered NOx and hydrocarbon emissions from engines.^{Footnote 2}
• Transportation associated with the combustion of gasoline^{Footnote 3} is a major contributor to emissions of VOC and CO; emissions of these pollutants have decreased by 82% and 67%, respectively, over this time period.
  • The decrease in emissions is despite a 58% increase in on-road light-duty gasoline trucks and vehicles and off-road spark-ignition engines, and is due to regulations that have effectively decreased sulphur levels in fuels and 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 68% and 70%, respectively, over this time period, in part owing to improvements in incineration technologies.

Despite significant decreases in emissions of most pollutants, since 2005 emissions of particulate matter have risen by 33% (TPM), 29% (PM₁₀) and 15% (PM_2.5). These increases are largely coming 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 2020 were 24% above 1990 levels, although 1% below 2005 levels. The upward trend in NH₃ emissions is primarily driven by the use of inorganic nitrogen fertilizer.

The subsequent sections of this chapter identify the important sources of emissions for each substance in 2020 and their varying contribution to total emissions over time (Table 2–2).

The full-time series of national, provincial and territorial pollutant emissions from 1990 to 2020 are available online on the Government of Canada Open Data Portal.

Notes:
Totals may not add up due to rounding.
Emissions of pollutants are expressed in either kt, kg, gTEQ or g.
Values in this report have been rounded to two significant digits.
0.00 Indicates emissions were truncated due to rounding.
- Indicates no emissions

Notes:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

The subsequent sections of this chapter identify the important sources of emissions for each substance in 2020 and their varying contribution to total emissions over time.

The full time series of national, provincial, and territorial pollutant emissions from 1990 to 2020 are available online on the Government of Canada Open Data Portal.

Table 2–2: Total air pollutant emissions in 2020 for Canada by source, sector and subsector

Notes:
Totals may not add up due to rounding.
Emissions of pollutants are expressed in either kt, kg, gTEQ or g.
Values in this report have been rounded to two significant digits.
0.00 Indicates emissions were truncated due to rounding.
- Indicates no emissions

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.

Note:
Refer to Annex 4.4 for more information on international marine navigation and air transportation reporting emissions.

Note:
a. PAH includes B(a)p, B(b)f, B(k)f, I(1,2,3-cd)p.