Archived: Air Pollutant Emission Inventory report: chapter 2

Chapter 2: 2015 emissions and trends

This chapter describes, for each pollutant, the main sources and sectors contributing to the 2015 emissions and to the historical trends. For the purpose of the present inventory, source categories are broken down into sectors (e.g. aluminium industry is a sector within the source category ore and mineral industries) and subsectors (e.g. primary aluminium smelting and refining is a subsector of the aluminium industry sector). A brief description of each sector is provided in Table 1-1.

The contribution of each source category to total emissions of air pollutants varies with substances (Table 2-1).^Footnote2 The dust source category is a particularly important source of particulate matter (PM) emissions, accounting for 62% of emissions of total particulate matter less than or equal to 2.5 microns (PM_2.5). The agriculture source category accounts for most ammonia (NH₃) emissions (94%), while incineration and waste sources account for a significant proportion of hexachlorobenzene (HCB) (62%) and dioxins/furans (D/F) (42%) emissions. The ore and mineral industries account for the largest proportion of sulphur oxides (SO_x) (46%), lead (Pb) (76%) and cadmium (Cd) (70%) emissions. The transportation and mobile equipment source category is the largest emitter of nitrogen oxides (NO_x) (54%) and carbon monoxide (CO) (53%). The oil and gas industry is the largest emitter of volatile organic compounds (VOCs) (37%). The ore and mineral industries and the incineration and waste sources each released about one third (31%) of the total mercury (Hg) emissions. The commercial/residential/institutional source category is a particularly significant source of polycyclic aromatic hydrocarbons (PAHs) (92%).

A few key sources exert a relatively large influence on the emissions of several pollutants or their trends. Among industrial sources, the non-ferrous mining and smelting industry is a major source of SO_x (35%), Pb (69%) and Cd (65%). Since 1990, the industry contributed significantly to the downward trends in emissions of these pollutants, as well as emissions of Hg. Over the years, the upstream petroleum industry has become a dominant source of VOC (36%) and NO_x (23%) emissions in Canada, with increasing trends in emissions of both pollutants. In contrast, electric power generation (coal) achieved important reductions in emissions of SO_x, NO_x, VOCs, HCB and Hg. Home firewood burning represents 92% of Canada’s PAH emissions and 21% of its CO emissions; it is also the dominant combustion source of PM_2.5. While transportation and mobile equipment sources remain large contributors to NO_x, VOC and CO emissions, emissions from these sources have decreased significantly since 1990.

The last year saw no significant change in the general downward trends of pollutant emissions. Emissions of SO_x continued to decline, largely due to decreasing emissions from upstream petroleum operations and coal-fired electric power generation. Improved control measures and changes in sulphur levels in fuel resulted in a decrease in PM_2.5 and D/F emissions from marine transport. Upgrades to the Rio Tinto Alcan smelter in the province of British Columbia resulted in a significant decrease in PAH emissions from the aluminium industry. Emissions of Cd have steadily declined in recent years, with reductions in emissions from several sources.

Notes:

Totals may not add up due to rounding.

Emissions of pollutants are expressed in either kt, kg, gTEQ or g.

This report's rounding protocol is based on an estimated uncertainty of 10-50% for all sectors, for which the protocol indicates rounding to two (2) significant digits.

- denotes no emissions.

The various components of each source category contribute varying proportions of emissions of each pollutant (Table 2-2). For example, within the dust source category, road dust and construction operations are the largest sources of total PM emissions (almost six times greater than agriculture, the next most significant source). The upstream petroleum industry is the largest emitter of VOCs, heavy-duty diesel vehicles are significant emitters of NO_x and off-road gasoline vehicles and equipment are large contributors of CO. The subsequent sections of this chapter identify the important sources of emissions for each substance in 2015 and their varying contribution to total emissions over time.

The full time series of national, provincial and territorial pollutant emissions from 1990 to 2015 are available through the Air Pollutant Emission Inventory Online Data Query Tool.

Notes:

Totals may not add up due to rounding.

-denotes no emissions.

• ^{Table 2-2 Note a} PAH includes B(a)p, B(b)f, B(k)f, I(cd)p.