Canada: Air Quality Standards

Canada: Air Quality Standards


Although Canada’s National Ambient Air Quality Objectives (NAAQOs) were established in the 1970s and remain in effect, the job of regulating air pollutants in Canada is shared between the NAAQOs and the Canada-Wide Standards, which were meant to harmonize standards between regions. Pollutant standards are usually delegated to one policy or the other.

Standard type
National ambient air quality standards and objectives


Canada currently uses two sets of air quality standards: National Ambient Air Quality Objectives (NAAQOs) and Canada-Wide Standards (CWS).

The first National Ambient Air Quality Objectives (NAAQOs) were created in the mid-70s, and are supported by Canada’s foremost federal environmental law, the Canadian Environmental Protection Act (CEPA).

In 1998, an alternative regulatory tool was adopted to help manage environmental issues within Canada. Canadian Environment Ministers (except Quebec) signed the Canada-Wide Accord on Environmental Harmonization, putting into effect a set of standards known as the Canada-Wide Standards (CWS). Under the CEPA 1999, CWS are considered Environmental Quality Objectives. In June 2000, CWS for PM and O3 were assigned, committing the nation (except Quebec) to significant reductions in PM and ground-level ozone by 2010.

Air pollutants recognized as problematic are either managed through the NAAQOs program or the CWS, not both. Some departments in the Canadian government, however, have integrated their NAAQOs and CWS divisions.

Technical Standards

Table of National Ambient Air Quality Objectives & Guidelines in Canada
Pollutant Averaging Time Maximum Desirable Level Maximum Acceptable Level Maximum Tolerable Level
Sulphur dioxide (SO2) annual
24 hours
1 hour
11 ppb
57 ppb
172 ppb
23 ppb
115 ppb
334 ppb

306 ppb
Total Suspended Particulate (TSP) annual
24 hours
60 µg/m3
70 µg/m3
120 µg/m3

400 µg/m3
Carbon Monoxide (CO) 8 hours
1 hour
5 ppm
13 ppm
13 ppm
31 ppm
17 ppm
Nitrogen Dioxide (NO2) annual
24 hours
1 hour
32 ppb

53 ppb
106 ppb
213 ppb

160 ppb
532 ppb
Ozone (O3) annual
24 hours
1 hour

15 ppb
51 ppb
15 ppb
25 ppb
82 ppb

153 ppb

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