Ambient Levels of Nitrogen Dioxide
- National ambient levels of nitrogen dioxide
- Regional ambient levels of nitrogen dioxide
- Ambient levels of nitrogen dioxide at monitoring stations
- Related indicators and other information
National ambient level of nitrogen dioxide
Nitrogen dioxide (NO2) and nitric oxide (NO), collectively referred to as nitrogen oxides (NOx), are emitted to the atmosphere from high-temperature combustion processes (car engines, power plants, industrial processes). Although primarily emitted as NO, NO2 is rapidly formed when it reacts with ozone (O3) and volatile organic compounds (VOC). The major sources of NO2 in Canada are on-road and off-road vehicles, the oil and gas industry and the use of fuel for electricity generation and heating. NO2 plays an important role in the formation of ozone in the atmosphere. It is a precursor to fine particulate matter (PM2.5) and contributes to acid rain. NO2 also has adverse health effects. It can irritate the lungs, decrease lung function and increase susceptibility to allergens for people with asthma.
In Canada, the average concentration of NO2 in the air for 2010 was 10.8 parts per billion (ppb), 6% lower than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 38% over that period. The decrease in NO2 concentration is consistent with the reduction in NOx emissions from cars and trucks as a result of the introduction of more stringent emissions standards from the federal government over the past years.
Nitrogen dioxide concentrations, Canada, 1996 to 2010
Note: The nitrogen dioxide (NO2) indicator is based on the annual average of the daily concentrations recorded at 58 monitoring stations across 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.
Regional ambient levels of nitrogen dioxide
Atlantic Canada
In Atlantic Canada, the average concentration of nitrogen dioxide (NO2) in the air in 2010 was 6.6 parts per billion (ppb), 65% higher than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 47% over that period. This decrease in concentration is mostly attributable to the reduction in nitrogen oxides (NOx) emissions from cars and trucks, as a result of more stringent emissions standards.
Nitrogen dioxide concentrations, Atlantic Canada, 1996 to 2010
Note: The nitrogen dioxide (NO2) indicator is based on the annual average of the daily concentrations recorded at 2 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
The average concentration of nitrogen dioxide (NO2) in the air for 2010 was 11.6 parts per billion (ppb), 2% lower than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 36% over that period. This decrease in concentration is mostly attributable to the reduction in nitrogen oxide (NOx) emissions from cars and trucks, as a result of more stringent emissions standards.
Nitrogen dioxide concentrations, Quebec, 1996 to 2010
Note: The nitrogen dioxide (NO2) indicator is based on the annual average of the daily concentrations recorded at 12 monitoring stations across Quebec. 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.
Ontario
In Ontario, the average concentration of nitrogen dioxide (NO2) in the air for 2010 was 11.1 parts per billion (ppb), almost identical to the concentration in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 45% over that period. This decrease in concentration is mostly attributable to the reduction in nitrogen oxide (NOx) emissions from cars and trucks, as a result of more stringent emissions standards.
Nitrogen dioxide concentrations, Ontario, 1996 to 2010
Note: The nitrogen dioxide (NO2) indicator is based on the annual average of the daily concentrations recorded at 15 monitoring stations across Ontario. 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 nitrogen dioxide (NO2) in the air for 2010 was 10.7 parts per billion (ppb), or 3% lower than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 36% over that period. This decrease in concentration is mostly attributable to the reduction in nitrogen oxide (NOx) emissions from cars and trucks, as a result of more stringent emissions standards.
Nitrogen dioxide concentrations, Prairies, 1996 to 2010
Note: The nitrogen dioxide (NO2) indicator is based on the annual average of the daily concentrations recorded at 13 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 nitrogen dioxide (NO2) in the air for 2010 was 10.6 parts per billion or 18% lower than in 2009. A declining trend was detected from 1996 to 2010, representing a concentration decrease of 32% over that period. This decrease in concentration is mostly attributable to the reduction in nitrogen oxide (NOx) emissions from cars and trucks, as a result of more stringent emissions standards.
Nitrogen dioxide concentrations, British Columbia, 1996 to 2010
Note: The nitrogen dioxide (NO2) indicator is based on the annual average of the daily concentrations recorded at 16 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 nitrogen 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 NO2 concentrations at specific monitoring stations.
Related indicators
- Ambient Levels of Fine Particulate Matter
- Ambient Levels of Ground-Level Ozone
- Ambient Levels of Sulphur Dioxide
- Ambient Levels of Volatile Organic Compounds
- International Comparison: Urban Air Quality
Other information
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