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 the use 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 2010, national mercury emissions totalled 4.7 tonnes (t), which is an 18% or about 1.0 t lower than 2009 levels. Mercury emissions in 2010 were 87% lower (30.3 t) than 1990 levels, 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 2010

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 2007-2010 estimates. However, they are not yet included in the estimates for previous years. Updates to historical trends are currently being compiled by the NPRI.
Source:  Environment Canada (2012) National Pollutant Release Inventory: Air Pollutant Emission Summaries and Trends.

Sources of mercury emissions to air

In 2010, the highest proportion of mercury emissions released to the air in Canada came from electric power generation, representing 33% (just under 1.6 t) of national emissions. Incineration represented the second-highest proportion of mercury emissions, with 20% (just less than 1.0 t) of national emissions. The non-ferrous smelting and refining industry was the third individual source, with 12% (over 0.5 t) of national mercury emissions.

Mercury emissions to air by source, Canada, 2010

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 (2012) National Pollutant Release Inventory: Air Pollutant Emission Summaries and Trends.

Regional mercury emissions to air

Ontario and Alberta were the provinces with the highest Hg emission levels in 2010, with each representing over 21% (1.0 t) of the national emissions. Alberta’s mercury emissions came mainly from electric power generation facilities and the petroleum industry. Ontario’s mercury emissions, in addition to coming from incineration sources and the iron and steel industries, came from the manufacturing of mercury-rich products and the cement and concrete industries. Saskatchewan had the third-highest Hg emissions in 2010, contributing 18% (over 0.8 t) of the national emissions, mostly from electric power generation. Quebec had the fourth-highest Hg emissions, contributing about 13% (just under 0.6 t) of the national emission levels. More than one-half of Quebec’s emissions were attributable to the incineration sector alone.

Mercury emissions to air by province and territory*, Canada, 2010

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 0.005 t).
Source:  Environment Canada (2012) National Pollutant Release Inventory: Air Pollutant Emission Summaries and Trends.

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 (2012) National Pollutant Release Inventory: Facility Data.

International mercury emissions to air

The latest information indicates that, in 2005, the global emissions^[1] of mercury to air from human activity were estimated to be 1930 tonnes (t). China contributed the most mercury to the atmosphere with 42.8% (825.2 t) of the total, followed by India with 8.9% (171.9 t), and the United States with 6.1% (118.4 t). Russia, with 3.8% (73.9 t) and Indonesia, with 3.5% (68.0 t), ranked fourth and fifth. Canada emitted 6.2 t, which corresponds to 0.3% of the global Hg emissions to air for 2005. Mercury emissions can travel tens to hundreds of kilometres via air masses before being deposited.^[2] For example, transboundary flows of Hg emissions from foreign sources account for over 95% of the anthropogenic mercury deposited in Canada.^[3]

Related indicators

• Emission of toxic substances to air