12. State - Air

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The air surrounding us on the land and in our communities is called “ambient” air.   It contains nitrogen, oxygen, a small amount of carbon dioxide and water vapour. It can also contain amounts of other substances that can be harmful to human health or the environment at certain levels.

Naturally occurring levels of these substances when present in the air are called background levels. Human activities and natural events, such as burning fossil fuels and wildfires, can elevate these levels in the ambient air above the background levels and cause air pollution. Tracking levels of the most common air pollutants provides an indication of air quality and help assess the impacts of human activities and natural events on air quality.

Air quality monitoring station.(c) GNWT


12.1 Trends in monitoring Criteria Air Contaminants

Criteria Air Contaminants (CACs) are monitored as indicators of air quality. CACs are common trace particles and gases found in the air around us. CACs include total suspended particulate (TSP), particulate matter 10 microns or less in diameter (PM10), particulate matter 2.5 microns or less in diameter (PM2.5) and gaseous pollutants, including sulphur dioxide (SO2), nitrogen oxide (NOx), carbon monoxide (CO) and ground level ozone (O3).

National and territorial standards establish limits for the maximum concentrations of particulates and gases that are acceptable in ambient air to protect the environment and human health. Actual measured concentrations are compared to these standards to determine the quality of air and whether it is safe for the environment and people.

Air Quality Monitoring Station, Yellowknife 2021


A variety of methods exist to measure individual CACs. These methods range in complexity and sophistication. Information for this indicator is obtained from the NWT Air Quality Monitoring Network (Ref. 1), a program operated by the Department of Environment and Climate Change (ECC) in collaboration with Environment and Climate Change Canada (ECCC) (Ref. 2). The Network consists of four monitoring stations in Yellowknife, Inuvik, Fort Smith and Norman Wells.

Pollutants monitored vary by station but include most, if not all, CACs. Wind speed, wind direction and temperature are also monitored.

This indicator was prepared by the Government of the Northwest Territories, Department of Environment and Climate Change, using information obtained from Environmental Stewardship and Climate Change Division and Environment and Climate Change Canada.


NWT Focus

The NWT has limited industrial development, a small population and many remote and small communities. The only relatively large community is Yellowknife.

Industrial development, in particular resource extraction such as mining and oil and gas, are likely to increase in the NWT in the future. Increased development is often associated with an increase in emissions of air pollutants. Population growth within communities, can also result in additional related emissions from sources such as diesel power generation, construction, vehicle use and commercial and residential heating. Data collected through the NWT Air Quality Network provides a basis for comparison and management of air quality and emissions and tracking of trends.


Current View: status and trend

Information from all air monitoring activities, along with some historical perspective and trend analysis, is presented annually in the NWT Air Quality Report (Ref. 3). Concentrations of CACs in the NWT are expected to be low, with readings at or below [ECC1] [Im2]  what would be considered typical background values.

Monitoring to date generally confirms the expected low levels for most potential air contaminants measured in the four NWT communities, with NWT air quality much better than the established ambient air quality standards.


Table 1. NWT Guidelines for Ambient Air Quality Standards

* micrograms per cubic metre    ** part per billion

Notable exceptions include the influence of wildfire smoke and dust events from road gravel after the thaw period. The summer of 2014 was an exceptionally active wildfire season, with very high ambient particulate (PM2.5) measurements in the South Slave Region (Fort Smith) and the North Slave Region (Yellowknife).

Overall, there has been no increasing or decreasing trends of O₃ and NO₂ levels in the NWT from 2011 to 2020, with concentrations representative of regional background concentrations. The O₃ levels are consistent from year to year and between the communities and well below the air quality standard of 63 ppb. NO₂ is relatively stable, which is to be expected given the absence of any major changes to emission sources or population growth in these communities. The NO₂ annual results are well below the air quality standard of 32 ppb. All concentrations of SO2 and CO consistently remain lower than the standards (SO2 and CO charts not shown).

Figure 1: Particulate (PM2.5) Annual Averages. Fort Smith station began operation in 2014. Source: NWT Air Quality Monitoring Network (Ref. 1).


Figure 2: Ozone (O3) Annual Averages. Fort Smith station began operation in 2014 and ozone analyzer was not installed until late 2014. Source: NWT Air Quality Monitoring Network (Ref. 1).


Figure 3: Nitrogen Dioxide (NO2) Annual Averages. Fort Smith station began operation in 2014. Source: NWT Air Quality Monitoring Network (Ref. 1).


Looking around

The measurement and use of CACs to assess air quality is a well-established approach across North America, Europe and many other jurisdictions. Three NWT monitoring stations (Inuvik, Yellowknife, and Fort Smith) are designated as part of the National Air Pollution Surveillance (NAPS) program, which monitors and compares air quality in communities across Canada. Information collected from NWT stations is summarized in annual reports.

Data from the NWT monitoring network is also used by other jurisdictions for comparative purposes in their air quality reporting; by the GNWT to manage and track air quality concerns; by consultants providing assessments in support of development projects in the NWT and by residents of the NWT and across Canada through the NWT Air Quality Monitoring Network web site.

Air quality monitoring data from Yellowknife station is used in the Canadian Environmental Sustainability Indicators (CESI) reports (www.canada.ca/en/environment-climate-change/services/environmental-indic...). NWT air quality data is supplied by ECC to the National Air Pollution Surveillance (NAPS) Program, which makes it available to the CESI authors.

In addition to comparing our air quality data within the NWT, Yellowknife air quality is compared to other cities in Canada. The most recent comparison was based on 2018 data, which is the latest information available from other jurisdictions at the time of writing. When looking at ambient air data from other locations, it is important to note that there are many influences on local air quality, including geographic considerations, population size and density, local industrial sources and transboundary considerations.

Yellowknife PM2.5 and NO2 levels were the lowest of all comparison jurisdictional capitals, presumably because of a smaller size city with fewer combustion emission sources. The O3 levels were the third highest of the cities compared. The reverse relationship between Yellowknife’s O3 and NO2 concentrations is generally to be expected, in part since localized NOx levels contribute to ozone reduction through a chemical process known as scavenging. Therefore, higher O3 levels may be expected in areas with lower NO2 concentrations.

Figure 4: National Comparisons - Jurisdictional Capitals. Source: NWT Air Quality Report 2018; no standard available for annual O3 (Ref. 4).


In comparison to select cities across Canada of a similar population size (<100,000), Yellowknife PM2.5 levels were the lowest. Yellowknife O3 levels were similar to those of the other cities. NO2 levels in Yellowknife were the lowest compared to other cities.

Figure 5: Comparisons of select communities across Canada with similar population size. Source: NWT Air Quality Report 2018; no standard available for annual O3 (Ref. 4).


Looking forward

Industrial development is expected to increase in the NWT with the development of mineral and oil and gas resources. It is reasonable to assume air emissions associated with these activities will also increase. Currently, the majority of industrial activity is occurring in remote areas and the potential risk to community air quality and residents is low. However, the potential for localized environmental impacts is present and if industrial activity becomes sufficiently intense and widespread, cumulative emissions could begin to affect regional air quality including the air in NWT communities.

Increased industrial activity may also trigger increased community growth in the form of commercial and residential developments. Emissions associated with these activities (increased space heating, power demands, vehicles) would have a more direct impact on community air quality.

Since combustion sources can be large source of CAC emissions, efforts to improve energy efficiency and/or the use of alternative energy sources to reduce greenhouse gas production will also have the co-benefit of reducing CAC emissions.

Wildfire smoke is a significant driver of air pollution in the NWT communities. Anticipated ongoing climate change will likely result to wildfire seasons that are longer, with more frequent and extreme fire events in the NWT and neighbouring provinces and territories (Ref. 5). Smoke from wildfires can reach the NWT over extended distances and cause the amount of particulate matter and chemicals in the ambient air to increase. By tracking background levels of particulate matter and other parameters in air, we can better assess the impacts of natural events and human activities on air quality that can affect us all.

A new air quality monitoring station will be established in Fort Simpson in 2022 to enhance monitoring of CACs. With the addition of the fifth station, there will be a monitoring station located in each administrative region of the territory. It is vital that the GNWT continues to measure quality across the NWT so that status and trends can be assessed.


Find out more

  • For more information on the NWT Air Quality Monitoring Network, including links to a data management, analysis and reporting system that provides public access to near real-time air quality data for each monitoring location, visit http://aqm.enr.gov.nt.ca/. Access to archived data is available by querying the database using web-based tools. The web site also provides additional information on the NWT Air Quality Monitoring Network, air pollutants, monitoring equipment and air quality standards, as well as links to monitoring information collected in other jurisdictions.
  • Annual monitoring data from all NWT stations is analyzed and presented in the annual NWT air quality reports at www.ecc.gov.nt.ca/en/services/air-quality.


Technical Notes

More detailed information on monitoring methodology is available on the NWT Air Quality Monitoring Network website (Ref. 1). Each station is a climate-controlled trailer with state-of-the-art monitoring equipment capable of continuously sampling and analyzing a variety of air pollutants and meteorological conditions. Using sophisticated data acquisition system and communications software, data from each station is automatically transmitted every hour to ECC headquarters in Yellowknife, allowing near real time review of community air quality by ECC staff. The data also undergoes a series of validity checks before being archived by ECC’s data management, analysis and reporting system.



Ref. 1. Government of the Northwest Territories, Department of Environment and Climate Change. 2021. NWT Air Quality Monitoring Network. Available at: http://aqm.enr.gov.nt.ca/

Ref. 2. Environment and Climate Change Canada. 2021. National Air Pollution Surveillance (NAPS) program. Available at: https://www.canada.ca/en/environment-climate-change/services/air-pollution/monitoring-networks-data/national-air-pollution-program.html

Ref. 3. Government of the Northwest Territories, Department of Environment and Climate Change. 2021. NWT Air Quality Reports. Available at: https://www.ecc.gov.nt.ca/en/services/air-quality

Ref. 4. Government of the Northwest Territories, Department of Environment and Climate Change. 2021. NWT Air Quality Report 2018. Available at: https://www.ecc.gov.nt.ca/sites/ecc/files/resources/2018_air_quality_report_v6.pdf

Ref. 5. Flannigan, M., Stock, B., Turetsky, M., & Wotton, M. 2008. Impacts of climate change on fire activity and fire management in the circumboreal forest. Global Change Biology, 14, 1-12. Available at: https://sites.ualberta.ca/~flanniga/publications/2008Impacts%20of%20climate%20change%20on%20fire%20activity%20and%20fire%20management%20in%20the%20circumboreal%20forest.pdf