Toxic substances list: sulphur dioxide

Sulphur dioxide (SO₂) is a colorless gas that smells like burnt matches. It can be chemically transformed into acidic pollutants such as sulphuric acid and sulpfates (sulphates are a major component of fine particles). SO₂ is generally a byproduct of industrial processes and burning of fossil fuels. Ore smelting, coal-fired power generators and natural gas processing are the main contributors. Sulphur dioxide is also the main cause of acid rain, which can damage crops, forests and whole ecosystems.

The PSL Assessment Report for PM₁₀specifies that PM₁₀ can be released directly into the atmosphere or formed secondarily in the atmosphere from precursors as a result of physical or chemical transformations and identifies SO₂as one of the principal precursors to PM₁₀, which is toxic and constitutes a danger in Canada to human life or health. An Order adding Sulphur Dioxide (SO₂) to the List of Toxic Substances of CEPA 1999 was published in Part II of the Canada Gazette of July 2, 2003.

SO₂ was also considered in the PSL Assessments for Releases from Primary and Secondary Copper Smelters and Copper Refineries and Releases from Primary and Secondary Zinc Smelters and Zinc Refineries. In these assessments, the risk due to SO₂ released from copper smelters/ refineries and zinc plants was analysed based on both direct exposure to SO₂ and on associated acidic deposition. Results for direct exposure indicate that there is a risk to vegetation over varying areas near both copper smelters/refineries and zinc plants, to a maximum distance of about 10 km. For acidic deposition, it was determined that copper smelters contributed up to 8% (relative to all anthropogenic and natural sources) of the SO₂ resulting in acidic deposition at the four eastern Canadian receptor areas considered. It has been proven that exposure to SO₂in ambient air is associated with severe adverse respiratory effects in humans, and affects sensitive individuals with pre-existing respiratory conditions such as asthma or bronchitis. Also, as a precursor to respirable particulate matter (PM₁₀), it has the potential for induction of cardio respiratory health effects.

CAS (Chemical Abstract Service) registry number: 7446-09-5

Risk assessment

Assessment Report - Respirable Particulate Matter Less Than or Equal to 10 Microns (PM-10)
Assessment Report - Releases from Primary and Secondary Copper Smelters and Refineries and Releases from Primary and Secondary Zinc Smelters and Refineries
Order Adding Toxic Substances to Schedule 1 to the Canadian Environmental Protection Act, 1999
CEPA 1999 Schedule 1 - List of Toxic Substances -This substance has been added to the List of Toxic Substances. 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.
c)constitute or may constitute a danger in Canada to human life or health.
Full life cycle management of the substance (Track 2) under the Toxic Substances Management Policy

Sources

This substance is entering the environment from the following sources:

Risk management strategy

Click on the following link to view strategies and actions recommended to manage risks associated with the substance:

Interim Plan 2001 on Particulate Matter and Ozone

Risk management tools

Tools developed to manage risks associated with the substance:

Consultation

Consultation (past and present) on the substance:

Consultations on potential amendments to Sulphur in Diesel Fuel Regulations

Other information

Contact

Substances Management Information Line
Chemicals Management Plan
Environment and Climate Change Canada
Gatineau, QC K1A 0H3

Telephone: 1-800-567-1999 (in Canada) or 819-938-3232
Email: substances@ec.gc.ca

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