National Pollutant Release Inventory: mercury

Every year, businesses, institutions and other facilities across Canada must report their releases and disposals of pollutants to air, water and land to the National Pollutant Release Inventory (NPRI). The publicly available information helps the government set environmental priorities and monitor environmental performance. It also provides Canadians with an opportunity to learn about pollution in their neighborhoods.

Mercury is part of the NPRI’s Substance Overview Series. This Substance Overview explores releases, disposals and transfers of mercury that are reported to the NPRI by a number of industries in Canada. It also summarizes what facilities do to mitigate their environmental impacts.

Mercury

Mercury (Hg) is a naturally occurring heavy metal that is found primarily in the form of the mineral, cinnabar, and may also be present in raw materials such as coal, crude oil and other fossil fuels. Once released, mercury can travel through air and water, to areas far from its source. It is the only metal that remains a liquid at room temperature and it can vaporize to produce a colourless, odourless gas. Liquid mercury is shiny and silver-white. Mercury is an element so it cannot be created or destroyed, but persists in the environment in several forms. One of these forms, known as methylmercury, can be toxic to living organisms even at low concentrations. Mercury is released to air, water and soil from a range of natural sources and human activities.

In Canada, mercury releases have declined since the 1980's, mainly due to the closure of industrial operations, the use of new emission control technologies and the increased of best management practices, particularly in the base metal smelting sector. The phase out of the use of mercury in a number of products (such as pesticides and cosmetics) and manufacturing processes (such as chlorine production and polyurethane production) also contributed to a reduction in mercury releases.

Effects on human health

In the environment, particularly lakes, waterways and wetlands, mercury may be converted to a toxic, organic compound called methylmercury. Living organisms absorb methylmercury much more easily than mercury. Methylmercury builds up in the tissues of living organisms as they age and consume food, and it becomes more concentrated in the food chain as larger predators eat smaller prey. In the general population, the key sources of exposure to mercury occur through the consumption of larger species of fish and country foods with high levels of mercury. Exposure can also occur when mercury-containing products are broken, releasing or spilling mercury at home or in the workplace.

In humans, methylmercury may affect the central nervous system. It is particularly damaging to fetuses, infants and young children, who are vulnerable due to their developing nervous systems.

Effects on the environment

Mercury is released into the air, water and soils from various natural sources such as:

• volcanic eruptions
• weathering of rocks and surfaces
• undersea vents
• forest fires
• emissions from water bodies

Mercury is also released by human activities such as:

• burning of fossil fuels (primarily coal)
• mining and base metal smelting
• cement production
• municipal and medical waste incineration
•  improper disposal of mercury-containing products

Mercury can be found in human-made products such as:

• fluorescent light bulbs
• batteries
• mercury fever thermometers and thermostats
• dental amalgam.  

While Canada no longer permits many of these products to use mercury, a number of Canadians may still have older products in their homes or workplaces.

Mercury moves over long distances on air currents and can be deposited on land and water far from the source of release. Mercury can be re-emitted from land and water back into the atmosphere through natural processes and cycle through the environment in various forms. These natural transformations and environmental pathways of mercury are complex and affected by local conditions. Understanding the relationships between local conditions and mercury levels in the environment is key to predicting changes in the concentration of mercury and its ability to be absorbed by living things.

For more information on the effects of mercury and how it moves through the environment, see the Canadian Mercury Science Assessment.

There are different programs that monitor the level of mercury in Canada’s environment. For more information, see Total Gaseous Mercury (TGM)  and Speciated Mercury.

The overall amount of mercury being released into the environment is on a declining trend due to policies, regulations and advances in technologies in Canada. However, the reductions do not generally result in lower concentrations in the environment due to its persistent nature, complex geochemical cycle and the increased industrialization of other countries. Emissions from human activities account for 40% of mercury deposited in Canada each year, and 97% of these emissions come from other countries.

Scientists are also working to determine what impact climate change will have on the global movement and cycling of mercury in the Canadian environment.

Reporting facilities

Facility owners and operators must report pollutant releases from activities at their facility if these releases are above a certain threshold. A facility must also indicate the primary activity that occurs at the site in order to identify the industrial sector to which the facility belongs.

Mercury is considered a Part 1B substance for the NPRI. These substances may have significant environmental and human health impacts at relatively low levels.

For more information on reporting requirements, consult our resources and guides.

In 2019, 254 facilities reported releases, disposals or transfers of mercury to the NPRI; 198 of these facilities reported releases. These covered several different industrial sectors, with mining and quarrying being the most frequent (with 67 facilities).

The “other” category in this map includes:

• petroleum and coal products
• aluminum
• oil and gas pipelines and storage
• wood products and others

For tips on how to use and understand NPRI data, please see our guide on using and interpreting NPRI data.

Facilities that reported releases, disposals and transfers of mercury in 2019

Total releases

In 2019, 1,950 kg of mercury were released by facilities that reported to the NPRI. This represents a 47% decrease from 2010 levels (3,657 kg).

In 2019, air releases represented 95% of total releases of mercury by facilities in Canada, while water releases contributed to the rest (5%). Releases to land were negligible.

Total releases of mercury in 2019

Releases to air

In 2019, 1,844 kg of mercury were released to air by facilities that reported to the NPRI. This represents a 44% decrease from 2010 levels (3,288 kg).

Electricity (570 kg) and Iron and steel (455 kg) were the largest sectors contributing to air emission of mercury.

The highest releases of mercury to air were located in Ontario (617 kg) and Saskatchewan (478 kg).

Releases of mercury to air for 2019

Releases to water

In 2019, 106 kg of mercury were released to water by facilities that reported to the NPRI. This represents a 59% decrease from 2010 levels (261 kg).

Waste and wastewater systems (60 kg) is the largest sector contributing to releases of mercury to water.  These facilities do not generate mercury, but they capture most of the mercury generated upstream from industrial sectors or from the use or disposal of products containing mercury, and release any remaining amounts to water.

The highest releases of mercury to water are located in British Columbia (40 kg) and Ontario (33 kg).

Releases of mercury to water for 2019

Disposals

In 2019, 120,042 kg of mercury contained in a number of waste materials were disposed of by facilities that reported to the NPRI. This represents a 30% decrease from 2010 levels (170,535 kg).

The majority of mercury quantities reported to the NPRI are from the waste treatment and disposal sector (76,534 kg). This sector manages different wastes containing mercury, such as industrial residues, by-products and contaminated soil.

Disposals of mercury for 2019

Transfers for treatment and recycling

In 2019, 102,799 kg of mercury contained in a number of waste materials were transferred off-site for treatment or recycling by facilities that reported to the NPRI. This represents a 50% increase from 2010 levels (52,255 kg).

The majority of this mercury was transferred off-site for treatment prior to final disposal and belongs to the waste treatment and disposal sector (80,348 kg).

Transfers of mercury for 2019

Canada's actions

To ensure that the level of mercury in the environment does not exceed concentrations which are expected from natural processes, governments are working with citizens, industries and environmental organizations to examine mercury management tools.

In 2010, the Government of Canada published the Risk Management Strategy for Mercury, which outlined its preventive actions toward the reduction of risks posed by mercury. Subsequent to this, the Government of Canada conducted an assessment of whether the risk management actions taken for mercury were effective in meeting this objective. In 2020, it summarized the results in the Evaluation of the Effectiveness of Risk Management Measures for Mercury.

Key actions taken by the Government of Canada include:

• Products Containing Mercury Regulations
• Reduction of Carbon Dioxide Emissions from Coal-fired Generation of Electricity Regulations
• Export of Substances on the Export Control List Regulations
• Canada's national strategy for lamps containing mercury

For a complete list of the Government of Canada’s actions to reduce mercury, see the list of risk management tools on the Toxic Substance List page for Mercury.

These actions, along with other actions taken by the provincial and territorial governments, as well as industry, have helped to decrease releases of mercury in Canada.

Consumer products

Ongoing comprehensive efforts are put in place in Canada and elsewhere to manufacture products with replacements for mercury, thereby minimizing or eliminating the presence of mercury in these products. Regulations are in place through the Canada Consumer Product Safety Act for a number of consumer products, as well as in the Canadian Environmental Protection Act, 1999.

The Products Containing Mercury Regulations came into force in 2015, and prohibit the manufacture and import of most products containing mercury or any of its compounds.  The Regulations set content limits for exempted products and require manufacturers and importers of these exempted products to report every three years.

Also, the Surface Coating Materials Regulations restrict the level of mercury in all surface coating materials advertised, sold, or imported into Canada. In addition, the Toys Regulations prohibit any compound of mercury in the surface coating material that is applied to a product that is used by a child in learning or play situations.

Environment and Climate Change Canada and Health Canada will continue to periodically and systematically measure the progress made in protecting human health and the environment from the risks of mercury through ongoing performance measurement for toxic substances.

International cooperation

The majority of mercury from human activities that is deposited in Canada comes from emissions of other countries. As a result, the Government of Canada has been actively working with its international partners to develop and implement the Minamata Convention on Mercury. The Convention, which entered into force in 2017, requires countries that are Parties to the treaty to reduce and control mercury throughout its lifecycle. It is intended for example to reduce global atmospheric emissions, supply, trade and demand for mercury, and by using environmentally sound solutions for storage of mercury and mercury-containing wastes. It also supports phasing out the use of mercury in certain products and a gradual phase down in the use of dental amalgam.

The Government of Canada is actively engaged in a number of other relevant regional and bilateral programs. These include the Great Lakes Water Quality Agreement and the Protocol on Heavy Metals under the Convention on Long-range Transboundary Pollution.

Great Lakes Water Quality Agreement

The Great Lakes are shared by Canada and the United States and are vital to the well-being of millions of people. These lakes:

• contain almost 20% of the world's surface freshwater
• sustain 4,000 species of plants and animals
• are the basis for billions of dollars in economic activity
• provide drinking water for tens of millions of Canadians and Americans

The Great Lakes Water Quality Agreement between Canada and the United States was first signed in 1972 and was modernized in 2012. It identifies shared priorities and actions needed to restore and protect the Great Lakes.

Under the Chemicals of Mutual Concern Annex, Canada and the United States committed to developing strategies that include research, monitoring and surveillance actions, as well as pollution prevention and other control mechanisms for harmful chemicals. Mercury is assessed across a series of different environmental indicators.

Protocol on Heavy Metals

Under the Convention on Long-Range Transboundary Air Pollution, the Protocol on Heavy Metals was adopted in 1998. One of its primary obligations requires parties to reduce their emissions of lead, cadmium and mercury below 1990 levels. Canada meets its annual reporting requirement under the Protocol through the Air Pollutant Emissions Inventory.

Pollution prevention

Facilities can do a number of things to prevent pollution and waste at the source. Examples of Pollution Prevention (P2) activities that facilities have used to target mercury include:

• materials substitution to reduce the use of mercury-based chemicals
• recovery, re-use or recycling of mercury-containing waste
• equipment, process or product design modifications to reduce the use of mercury
• biological testing of employee blood mercury levels

Learn more about pollution prevention and how facilities and individuals can help protect the environment.

Analysis

These charts provide a more in-depth look at releases, disposals and transfers of mercury reported to the NPRI. Click on the different chart items to find out more.

There is more information about the NPRI and the substances that it tracks.

For further analysis, check out other NPRI maps and datasets. You can also use NPRI data to create your own analysis.