Nitrogen oxide emissions

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Nitrogen oxides (NOX) include emissions of nitric oxide (NO) and nitrogen dioxide (NO2). Nitrogen dioxide can have adverse effects on human health and the environment. Nitrogen oxides contribute to acid rain, which can lead to the acidification of aquatic and terrestrial ecosystems. It also contributes to the eutrophication of lakes and to the formation of ground-level ozone and fine particulate matter.

Key results

  • In 2015, NOX emissions were 1894 kilotonnes (kt). This is 22% lower than in 1990.
  • Transportation (road, rail, air and marine) was a major source of NOX representing 44% (825 kt) of emissions in 2015.

Total nitrogen oxide emissions by source, Canada, 1990 to 2015

Stacked column chart showing nitrogen oxide emissions by source. Long descriptio below.

Long description

The stacked column chart shows total nitrogen oxide emissions in Canada by source (transportation [road, rail, air and marine], oil and gas industry, other sources, off-road vehicles and mobile equipment, and electric utilities) for the years 1990 to 2015. The emissions are reported in kilotonnes.

Data for this chart
Total nitrogen oxide emissions by source, Canada, 1990 to 2015
YearTransportation (road, rail, air and marine) (emissions in kilotonnes)Oil and gas industry (emissions in kilotonnes)Other sources (emissions in kilotonnes)Off-road vehicles and mobile equipment (emissions in kilotonnes)Electric utilities (emissions in kilotonnes)Total national emissions (emissions in kilotonnes)
19901063.2344.8397.4360.9253.32419.5
1991985.4338.0382.0358.6248.02312.1
19921029.6353.9374.2366.7257.92382.3
19931044.7379.5382.8380.7237.22425.0
19941120.6411.3389.7383.7233.22538.4
19951128.4427.2388.0409.8243.72597.0
19961143.4440.4384.9436.5264.82670.0
19971234.6483.7383.7443.4282.52827.9
19981321.0494.9370.7390.6302.42879.7
19991375.4513.0373.5380.8298.22940.9
20001380.9458.1376.3378.7307.72901.7
20011327.4457.0355.0328.4296.02763.8
20021260.4455.9377.6317.3300.02711.2
20031186.1506.1371.7334.9283.72682.6
20041152.0435.3361.4335.7255.62540.0
20051133.2436.3338.1302.3245.82455.6
20061087.0455.1296.0279.7224.62342.4
20071054.4466.1282.3281.0239.12322.8
20081013.7470.2261.2271.9225.42242.4
2009906.9469.7233.8257.3218.22085.8
2010916.4460.4242.3274.5233.92127.5
2011908.2471.3248.6247.6200.12075.8
2012887.3459.0246.2218.4166.31977.1
2013869.5459.5240.8210.7161.91942.5
2014844.2471.1244.3201.4166.81927.8
2015824.8467.4248.2201.4151.91893.8

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How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only. The category "other sources" includes emissions from ore and mineral industries, manufacturing, building heating and energy generation, home firewood burning, incineration and waste, agriculture (livestock, crop production and fertilizer), dust and fires, paints and solvents, and other miscellaneous sources. Consult Table 1 in the Data sources and methods for a complete list of the air pollutant emissions sources included under each category.
Source: Environment and Climate Change Canada (2017) Air Pollutant Emission Inventory.

More information

While transportation (road, rail, air and marine) was the main contributor of NOX, it was also the sector that experienced the largest reduction between 1990 and 2015. Emissions of NOX from this sector decreased by 22% from 1063 kt to 825 kt.

The oil and gas industry emitted the next largest proportions of NOX emissions in 2015, representing 25% of total national emissions. This sector also experienced the largest increase (123 kt) in emissions between 1990 and 2015, partly offsetting reductions from other sectors.

The decline in NOX emissions between 1990 and 2015 is mostly attributable to two factors:

  • the reduction in emissions from transportation after 2000, given the progressive introduction of cleaner technology and fuels for vehicles
  • a reduction in emissions from electric utilities as a result of regulations and domestic and international agreements

Nitrogen oxide emissions by province and territory

Key results

  • Alberta emitted the majority of Canada's NOX in 2015. The province accounted for 36% (688 kt) of national emissions.
  • Between 1990 and 2015, the largest reduction was observed in Ontario. Emissions decreased by 50% (313 kt) in the province.

Nitrogen oxide emissions by province and territory, Canada, 1990 and 2015

Column chart showing nitrogen oxide emissions by province and territory. Long description below.

Long description

The column chart shows 1990 and 2015 nitrogen oxide emissions in Canada by province and territory. The emissions are reported in kilotonnes.

Data for this chart
Nitrogen oxide emissions by province and territory, Canada, 1990 and 2015
Province or territory1990 (emissions in kilotonnes)2015 (emissions in kilotonnes)
Newfoundland and Labrador59.064.3
Prince Edward Island7.14.9
Nova Scotia101.470.7
New Brunswick82.532.4
Quebec347.3223.5
Ontario624.4311.5
Manitoba71.547.7
Saskatchewan143.3144.0
Alberta645.3688.3
British Columbia318.0276.4
Yukon3.71.0
Northwest Territories and Nunavut16.229.1

Download data file (Excel/CSV; 804 B)

How this indicator was calculated

Note: The indicator reports air pollutant emissions from human activities only.
Source: Environment and Climate Change Canada (2017) Air Pollutant Emission Inventory.

More information

The oil and gas industry is an important source of NOX emissions in Alberta, accounting for 54% (369 kt) of the province’s NOX emissions in 2015. This sector is also responsible for the increase in emissions in this province between 1990 and 2015.

Ontario contributed the second-largest proportion of NOX emissions in 2015, with 16% (312 kt) of national emissions, with transportation (road, rail, air and marine) being the most important source followed by off-road vehicles and mobile equipment. Ontario experienced the largest decrease in emissions levels (313 kt) between 1990 and 2015 in large part due to emission reductions from transportation and electric utilities.

British Columbia ranked third, with 15% (276 kt) of national emissions. Transportation (road, rail, air and marine) was the most important source of NOX in this province as well.

Nitrogen oxide emissions from facilities

Environment and Climate Change Canada's National Pollutant Release Inventory provides detailed information on air pollutant emissions from industrial and commercial facilities. The Canadian Environmental Sustainability Indicators (CESI) program provides access to this information through an online interactive map.

With the CESI interactive map, you can zoom in to local areas and obtain details on NOX emissions specific to reporting facilities.

Source: Environment and Climate Change Canada (2016) National Pollutant Release Inventory Data search – facility reported data.

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