Ambient Levels of Nitrogen Dioxide

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Nitrogen dioxide (NO2) belongs to a group of substances called nitrogen oxides (NOX).Footnote [1] Nitrogen oxides are emitted into the atmosphere from high-temperature combustion processes such as vehicle engines, power plants and industrial processes. The major sources of nitrogen oxides in Canada are on-road and off-road vehicles, the oil and gas industry, and the use of fuel for electricity generation and heating. Nitrogen dioxide plays an important role in the formation of ozone in the atmosphere. It is a precursor to fine particulate matter, and contributes to acid deposition and eutrophication. Nitrogen dioxide also has adverse health effects: it can irritate the lungs, decrease lung function and increase susceptibility to allergens for people with asthma.

The annual average NO2 concentration indicators are based on the annual average of hourly NO2 concentrations.

National ambient level of nitrogen dioxide

In 2014, the national annual average concentration of NO2Footnote [2] was 8.9 parts per billion (ppb), or 0.7% lower than in 2013.

Since 2000, a decreasing trend of 0.5 ppb per year was detected. This was largely due to the federal government introducing progressively more stringent emissions standards that led to NOX emission reductions from cars and trucks.

Nitrogen dioxide concentrations, Canada, 2000 to 2014

Line chart of the national annual average concentrations of nitrogen dioxide - Long description below

Long description

The line chart shows the national annual average concentrations of nitrogen dioxide from 1999 to 2014. A decreasing trend was detected from 2000 to 2014.

Data for this chart
Nitrogen dioxide concentrations, Canada, 2000 to 2014
YearAnnual average concentration (parts per billion)
200015.0
200114.2
200213.2
200313.4
200412.8
200512.3
200611.8
200711.2
200810.9
200910.4
20109.6
20119.6
20129.0
20139.0
20148.9
Annual trend-0.5

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How this indicator was calculated

Note: The national annual average nitrogen dioxide concentration indicator is based on the annual average of the hourly concentrations recorded at 85 monitoring stations across Canada.
Source: Environment and Climate Change Canada (2016) National Air Pollution Surveillance Program.

Regional ambient levels of nitrogen dioxide

In 2014, the annual average concentrations of NO2 in the air varied from 4.4 ppb in Atlantic Canada to 10.5 ppb in British Columbia. Concentrations of NO2 were lower in Atlantic Canada, southern Quebec and the Prairies and northern Ontario region than in 2013. However, concentrations were higher in southern Ontario and British Columbia in 2014 compared to the previous year.

Since 2000, decreasing trends in NO2 concentrations were observed for all regions in Canada. Southern Ontario had the largest decreasing trend at 0.7 ppb per year, followed by southern Quebec and British Columbia with 0.5 ppb per year and 0.4 ppb per year, respectively. Atlantic Canada had a decreasing trend of 0.3 ppb per year, while the Prairies and northern Ontario region had a decreasing trend of 0.2 ppb per year.

Regional nitrogen dioxide concentrations, 2000 to 2014

Line chart of the annual regional average concentrations of nitrogen dioxide - Long description below

Long description

The line chart shows the annual average concentrations of nitrogen dioxide from 2000 to 2014 for five regions in Canada: Atlantic Canada, southern Quebec, southern Ontario, Prairies and northern Ontario, and British Columbia. Since 2000, decreasing trends were observed for all regions.

Data for this chart
Regional nitrogen dioxide concentrations, 2000 to 2014
YearAtlantic Canada annual average concentration (parts per billion)Southern Quebec annual average concentration (parts per billion)Southern Ontario annual average concentration (parts per billion)Prairies and northern Ontario annual average concentration (parts per billion)British Columbia annual average concentration (parts per billion)
2000n/a15.518.611.215.6
200112.514.618.210.714.4
20027.413.517.010.713.6
20038.315.516.810.913.4
20046.513.815.810.113.2
20055.613.616.39.612.7
20063.911.713.89.713.2
20074.111.713.09.611.8
20085.212.212.78.511.6
20094.310.910.89.111.6
20104.111.110.79.09.9
20114.610.810.68.59.7
20123.99.39.67.810.1
20135.08.89.58.310.0
20144.48.49.87.910.5
Annual trend-0.3-0.5-0.7-0.2-0.4

Note: n/a = not available.

Download data file (Excel/CSV; 1.65 KB)

How this indicator was calculated

Note: The annual average nitrogen dioxide concentration indicator is based on the annual average of the hourly concentrations recorded at 5 monitoring stations in Atlantic Canada, 14 in southern Quebec, 20 in southern Ontario, 21 in the Prairies and northern Ontario and 25 in British Columbia. There was no value for the Atlantic Canada region in 2000 because there were only two stations with reported concentrations. At least three stations are required to report a concentration value for a given year.
Source: Environment and Climate Change Canada (2016) National Air Pollution Surveillance Program.

Ambient levels of nitrogen dioxide at monitoring stations

The National Air Pollution Surveillance program measures air pollutant concentrations at monitoring stations across Canada. The Canadian Environmental Sustainability Indicators provide this information through an interactive indicator map. With the interactive map, you can drill down to NO2 concentrations at specific monitoring stations.

Related indicators

Other information

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