Mercury Emissions to Air
Mercury (Hg) is a naturally occurring metal that can be released to the air by natural processes such as soil and rock erosion and volcanic activity. Mercury can also be released to the air by human activities such as metal smelting, iron and steel production, coal-fired electricity generation, industrial boilers, cement kilns, waste incineration, and from the improper disposal of products such as electrical switches and fluorescent lights.
Mercury can be transported through the air and deposited into water or onto land. It can be transformed by microorganisms into methylmercury, a toxic form of mercury that is harmful to both humans and wildlife. Methylmercury can bioaccumulate in the food chain and enter our bodies through the ingestion of contaminated food. Mercury accumulated in vegetation can also be re-emitted to the air during forest fires.
In 2011, national mercury emissions totalled 3.7 tonnes (t), which is a 22% (about 1.0 t) decrease from the 2010 level. Mercury emissions in 2011 were 90% lower (31.3 t) than in 1990, the baseline year of this time series. The large decline in emissions since the 1990s is principally due to the adoption of various emission-reduction technologies in the non-ferrous smelting and refining sector, the closing of certain facilities, and compliance with the federal and provincial legislation and guidelines introduced over that period. Improvements in fossil fuel-fired electricity generation and incineration also contributed to the decline.
Mercury emissions to air, Canada, 1990 to 2011
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How this indicator was calculated
Note: Emissions from natural sources (e.g. volcanoes) and open sources (e.g. landfill waste) are not included in the indicator. Hg emissions from products are included in the 2007–2011 emission estimations. However, they are not yet included in the estimates for previous years. Updates to historical trends are currently being compiled by the National Pollutant Release Inventory (NPRI).
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Air Pollutant Emissions Data..
Sources of mercury emissions to air
In 2011, the highest proportion of mercury emissions released to the air in Canada came from the combustion of fuels for electric power generation, representing 27% (just under 1.0 t) of national emissions. Incineration released the second-highest proportion of mercury emissions, with 26% (just less than 1.0 t) of national emissions. The iron and steel industries released 12% (0.4 t) of national mercury emissions, making them the third-greatest individual source.
Mercury emissions to air by source, Canada, 2011
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How this indicator was calculated
Note: Emissions from natural sources (e.g. volcanoes) and open sources (e.g. landfill waste) have not been included in the indicator. “Other Sources” include all the other industrial, residential and commercial combustion, transportation and other miscellaneous sources not mentioned in this chart.
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Air Pollutant Emissions Data.
Regional mercury emissions to air
Ontario and Saskatchewan were the provinces with the highest mercury emission levels in 2011, representing 27% (1.0 t) and 20% (0.7 t) of the national emissions respectively. Ontario’s mercury emissions came mainly from iron and steel industries, incineration sources and cement and concrete industries, in addition to non-industrial sources such as electric power generation (utilities). The majority of Saskatchewan’s mercury emissions came from electric power generation (utilities) and the iron and steel industries. Quebec had the third-highest mercury emissions in 2011, contributing 18% (over 0.6 t) of the national emissions, mostly from incineration sources. Alberta had the fourth-highest mercury emissions, contributing 13% (just under 0.5 t) of the national emission levels.
Mercury emissions to air by province and territory*, Canada, 2011
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How this indicator was calculated
Note: Emissions from natural sources (e.g. volcanoes) and open sources (e.g. landfill waste) have not been included in the indicator.
*Mercury emissions for the territories are not shown in this chart because of their low values (less than 0.01 t).
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Air Pollutant Emissions Data.
Local mercury emissions from industrial facilities
Environment Canada’s National Pollutant Release Inventory (NPRI) provides detailed information on air pollutant emissions from industrial facilities. The Canadian Environmental Sustainability Indicators (CESI) provides access to this information through an online interactive map.
With the CESI interactive map, you can drill down to local areas and obtain details on mercury emissions from individual industrial facilities.
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Facility Reported Data.
International mercury emissions to air
The latest information indicates that, in 2010, the global emissions[1] of mercury to air from human activity were estimated to be 1960 tonnes (t). East and Southeast Asia account for 40% (777 t) of the global total, with China contributing about three quarters of this region’s emissions, or approximately one third of the total. Sub-Saharan Africa ranked second, with 16% (316 t), followed by South America, with 13% (245 t). South Asia ranked fourth, with 7.9% (154 t), and the Commonwealth of Independent States (CIS) & other European countries ranked fifth, with 6% (115 t). Canada emitted under 5 t, which corresponds to less than 1% of the global Hg emissions to air for 2010. Mercury emissions can travel hundreds to thousands of kilometres via air masses before being deposited.[2] For example, transboundary flows of Hg emissions from foreign sources accounted for over 95% of the anthropogenic mercury deposited in Canada in 2006.[3]
Related indicators
[1] United Nations Environmental Program (UNEP) Chemical Branch (2013) Global Mercury Assessment 2013: Sources, emissions, release, and environmental transport.
[2] Durnford D, Dastoor A, Figueras-Nieto D, Ryjkov A. Long-range transport of mercury to the Arctic and across Canada. Atmos Chem Phys Discuss 10:4673–4717. doi:10.5194/acpd-10-4673-2010, 2010.
[3] Environment Canada and Health Canada (2010) Risk management strategy for mercury.
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