Ambient Levels of Sulphur Dioxide
- National ambient levels of sulphur dioxide
- Regional ambient levels of sulphur dioxide
- Ambient levels of sulphur dioxide at monitoring stations
- Related indicators and other information
National ambient levels of sulphur dioxide
Sulphur dioxide (SO2) is a gas emitted when a fuel or a raw material containing sulphur is burned or used in industrial processes like metal ore smelting. The major sources of SO2emissions in Canada are the combustion of fuel for electricity generation and heating, and processes in both the non-ferrous smelting and refining industry and the oil and gas industry. SO2 emissions contribute to acidic deposition and are a major precursor to fine particulate matter (PM2.5). High concentrations of SO2 can cause adverse effects on respiratory systems of humans and animals, and can damage vegetation.
In 2010, the average concentration of sulphur dioxide in the air was 1.8 parts per billion (ppb) in Canada, 17% lower than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 62% over that period. The decrease of SO2 in the air is mainly due to the reduction in SO2 emissions observed in Canada resulting from efforts to curb acid rain and ambient particulate matter, and federal regulations on sulphur content in fuels.
Sulphur dioxide concentrations, Canada, 1996 to 2010
Note: The sulphur dioxide (SO2) indicator is based on the annual average of the daily concentrations recorded at 45 monitoring stations across Canada. Monitoring stations located close to major sources may have a great impact on the measured SO2 levels. A trend line is reported only when a statistical trend is detected at the 90% confidence level.
Source: Environment Canada (2012) National Air Pollution Surveillance (NAPS) program.
Regional ambient levels of sulphur dioxide
Atlantic Canada
In Atlantic Canada, the average concentration of sulphur dioxide (SO2) in the air in 2010 was 1.1 parts per billion (ppb), 11% lower than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 90% over that period. Emission reduction measures put in place at power plants in Atlantic Canada and the United States contributed to the reduction of SO2 in the air.
Sulphur dioxide concentrations, Atlantic Canada, 1996 to 2010
Note: The sulphur dioxide (SO2) indicator is based on the annual average of the daily concentrations recorded at 3 monitoring stations across Atlantic Canada. A trend line is reported only when a statistical trend is detected at the 90% confidence level.
Source: Environment Canada (2012) National Air Pollution Surveillance (NAPS) program.
Quebec
In Quebec, the average concentration of sulphur dioxide (SO2) in the air for 2010 was 1.9 parts per billion (ppb), 40% lower than in 2009.[1] A declining trend was detected from 1996 to 2010, representing a concentration decrease of 57% over that period. Emission reduction measures, put in place in Quebec at non-ferrous smelters and pulp and paper plants and in the United States at power plants, contributed to the reduction of SO2 in the air.
Sulphur dioxide concentrations, Quebec, 1996 to 2010
Note: The sulphur dioxide (SO2) indicator is based on the annual average of the daily concentrations recorded at 14 monitoring stations across Quebec. Monitoring stations located close to major sources may have a great impact on the measured SO2 levels. A trend line is reported only when a statistical trend is detected at the 90% confidence level. Four monitoring stations in 1996 and 3 in 2010 located close to industrial sources did not report concentrations for these years and partially explain the results in the chart.
Source: Environment Canada (2012) National Air Pollution Surveillance (NAPS) program.
Ontario
In Ontario, the average concentration of sulphur dioxide (SO2) in the air for 2010 was 2.0 parts per billion (ppb), or 8% lower than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 65% over that period. Emission reduction measures put in place for power plants and for the non-ferrous refining and smelting industry contributed to the reduction of SO2 in the air.
Sulphur dioxide concentrations, Ontario, 1996 to 2010
Note: The sulphur dioxide (SO2) indicator is based on the annual average of the daily concentrations recorded at 11 monitoring stations across Ontario. Monitoring stations located close to major sources may have a great impact on the measured SO2 levels. A trend line is reported only when a statistical trend is detected at the 90% confidence level.
Source: Environment Canada (2012) National Air Pollution Surveillance (NAPS) program.
Prairies
In the Prairies, the average concentration of sulphur dioxide (SO2) in the air was 0.8 parts per billion (ppb), or 5% lower than in 2009.A declining trend was detected from 1996 to 2010, representing a concentration decrease of 65% over that period. Emission reduction measures put in place at power plants and oil and gas facilities contributed to the reduction of SO2 in the air.
Sulphur dioxide concentrations, Prairies, 1996 to 2010
Note: The sulphur dioxide (SO2) indicator is based on the annual average of the daily concentrations recorded at 7 monitoring stations across the Prairies. A trend line is reported only when a statistical trend is detected at the 90% confidence level.
Source: Environment Canada (2012) National Air Pollution Surveillance (NAPS) program.
British Columbia
In British Columbia, the average concentration of sulphur dioxide (SO2) in air for 2010 was 2.6 parts per billion or 35% higher than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 23% over that period.
Sulphur dioxide concentrations, British Columbia, 1996 to 2010
Note: The sulphur dioxide (SO2) indicator is based on the annual average of the daily concentrations recorded at 10 monitoring stations across British Columbia. A trend line is reported only when a statistical trend is detected at the 90% confidence level.
Source: Environment Canada (2012) National Air Pollution Surveillance (NAPS) program.
Ambient levels of sulphur dioxide at monitoring stations
The National Air Pollution Surveillance (NAPS) program provides detailed information on air pollutant concentrations from monitoring stations across Canada. Canadian Environmental Sustainability Indicators (CESI) provide access to this indicator through an online interactive map. With the CESI interactive map, you can drill down to local areas and obtain details on SO2 concentrations at specific monitoring stations.
Related indicators
- Ambient Levels of Fine Particulate Matter
- Ambient Levels of Ground-Level Ozone
- Ambient Levels of Nitrogen Dioxide
- Ambient Levels of Volatile Organic Compounds
- International Comparison: Urban Air Quality
Other information
[1] Part of this large drop is attributable to the absence of monitoring data in 2010 from three stations included in the time series and located close to industrial areas.
- Date Modified: