Emission of Toxic Substances to Air
Toxic substances, when released to the air, are known to have harmful effects on human health, wildlife and biological diversity. For instance, toxic metals and organic pollutants can be inhaled or deposited onto the soil and into water, where they can enter the food chain and accumulate in body tissues. These substances can also be transported over great distances through the air.
The following Canadian Environmental Sustainability Indicators (CESI) track the emission of two toxic substances, mercury and hexavalent chromium, to the air. Both of these substances are listed as toxic under the Canadian Environmental Protection Act, 1999 (CEPA 1999) and therefore their release to the environment is closely monitored. The data used to calculate these indicators are taken from the National Pollutant Release Inventory (NPRI).
National and regional emissions of these substances are provided, with emissions broken down by source. A comparison of Canadian mercury emissions to those of other countries is also presented.
Emission of toxic substances to air by substance
 Section 64 of CEPA 1999 defines a substance as toxic if it is entering or may enter the environment in a quantity or concentration or under conditions that: a) Have or may have an immediate or long-term harmful effect on the environment or its biological diversity; b) Constitute or may constitute a danger to the environment on which life depends; or c) Constitute or may constitute a danger in Canada to human life or health.
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