Emissions of Hexavalent Chromium to Air
Chromium is a naturally occurring metal that is present in small amounts throughout the environment. Chromium occurs at low concentrations in the atmosphere through natural processes (e.g. soil and rock erosion, forest fires, volcanoes). Through human activities, chromium is added to the environment, primarily in particulate form when emitted to air.
In Canada, hexavalent chromium Cr(VI) and its compounds[1] are released to the air as by-products of fossil fuel combustion (e.g. for electricity generation) and various industrial processes (e.g. aerospace products and parts manufacturing, pulp and paper mills).
Cr(VI) and its compounds are of interest because they are declared toxic substances[2] under the Canadian Environmental Protection Act, 1999 (CEPA 1999) and because Cr(VI) is a known carcinogen. Cr(VI) and its compounds are directly subject to federal risk management actions (e.g. regulations for chromium electroplating, anodizing and reverse etching and required pollution prevention plans for wood preservation facilities).
Emissions of Cr(VI) in 2011 were 0.8 t,[3] or 25% lower than in 2010. This decrease can be for the most part attributed to emission reductions from facilities in the electricity generation, transmission and distribution sector; from a forging and stamping plant; and from two paint, coating and adhesive manufacturing facilities.
Hexavalent chromium emissions to air, Canada, 2003 to 2011
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How this indicator was calculated
Note: The indicator only includes the tonnes of Cr(VI), including that released in substances containing Cr(VI), reported in the National Pollutant Release Inventory (NPRI) based on the NPRI reporting criteria for emissions of Cr(VI) and its compounds. As a result, the Cr(VI) emissions presented here represent only a portion of the atmospheric emissions of this toxic pollutant in Canada.
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Facility Reported Data.
Emissions of Cr(VI) in Canada in 2011 were 71% lower than in 2003. Part of this reduction can be explained by a combination of changes in industrial production processes, regulation and the introduction of emission-control equipment and pollution-prevention activities in certain facilities.[4] Comparing the years 2003 and 2011, the greatest emission reductions were found in the motor vehicle manufacturing sector; the glass and glass products sector; the aerospace products and parts manufacturing sector; the electric power generation, transmission and distribution sector; and the coating, engraving, heat treating and allied activities sector.
Sources of emissions of hexavalent chromium to air
In 2011, 49% (or 0.4 t) of the national emissions of hexavalent chromium Cr(VI) came from electricity generation, transmission and distribution. Emissions of Cr(VI) from pulp, paper and paperboard mills represented 24% (0.2 t) of the national emissions.
Hexavalent chromium emissions to air by source, Canada, 2011
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How this indicator was calculated
Note: The indicator only includes the tonnes of Cr(VI), including that released in substances containing Cr(VI), reported in the National Pollutant Release Inventory (NPRI) based on the NPRI reporting criteria for emissions of Cr(VI) and its compounds. As a result, the Cr(VI) emissions presented here represent only a portion of the atmospheric emissions of this toxic pollutant in Canada. “Other Sources” represents a grouping of all other sources with Cr(VI) and its compounds emissions that are not individually displayed on this chart.
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Facility Reported Data.
Regional emissions of hexavalent chromium to air
Alberta facilities emitted the highest proportion of hexavalent chromium (Cr(VI)) in 2011, representing 56% (over 0.4 t) of national emissions, mainly from coal-fired electricity generation facilities. British Columbia facilities contributed 17% (more than 0.1 t) of national emissions. The biggest sources of Cr(VI)in British Columbia were the pulp, paper and paperboard mills. Coating, engraving, heat treating and allied activities were the most important source of Cr(VI) in Ontario; this province was the third-highest source, with 16% (over 0.1 t) of national emissions.
Hexavalent chromium emissions to air by province and territory*, Canada, 2011
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How this indicator was calculated
Note: The indicator only includes the tonnes of Cr(VI), including that released in substances containing Cr(VI), reported in the National Pollutant Release Inventory (NPRI) based on the NPRI reporting criteria for emissions of Cr(VI) and its compounds. As a result, the Cr(VI) emissions presented here represent only a portion of the atmospheric emissions of this toxic pollutant in Canada.
* Facility emissions of Cr(VI) and its compounds were not reported for the remaining provinces and the territories.
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Facility Reported Data.
Local hexavalent chromium emissions from facilities
Environment Canada’s National Pollutant Release Inventory (NPRI) provides detailed information on air 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 hexavalent chromium emissions from individual industrial facilities.
Source: Environment Canada (2013) National Pollutant Release Inventory Online Data Search - Facility Reported Data.
Related indicators
[1] Hexavalent chromium compounds are substances containing hexavalent chromium.
[2] 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.
[3] The indicator only includes the tonnes of Cr(VI), including that released in substances containing Cr(VI), reported in the National Pollutant Release Inventory (NPRI) based on the NPRI reporting criteria for emissions of Cr(VI) and its compounds. As a result, the Cr(VI) emissions represent only a portion of the atmospheric emissions of this toxic pollutant in Canada.
[4] The use of new methods by submitting facilities to estimate emissions also accounts for some of the decrease.
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