2021 Annual Regional Air Quality Index Statistics

Ministère de l’Environnement, de la Lutte contre les changements climatiques, de la Faune et des Parcs

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2021 Annual Regional Air Quality Index Statistics

The Air Quality Index (AQI) was calculated in 2021 for 24 weather regions, the Island of Montréal being divided into four sub-regions.

The percentage of days in which the AQI was deemed “good” or “acceptable” varied from 95% in the Île de Montréal - Nord sub-region (345/365) to 99% for the Témiscouata, Rivière-du-Loup, Laurentides and Haute-Gatineau regions.

The Île de Montréal - Nord sub-region, located in Montréal, was where air quality was most often “poor*”, with a proportion of 5% (20/365 days). The result was stable compared to 2020, where the proportion was 4%.

In overall terms, the respective AQI “good,” “acceptable” and “poor” proportions were 62%, 36% and 2%. Compared to 2020, the proportion of results in the “acceptable” and “poor” categories increased by 3% and 1%, respectively, to the detriment of the results in the “good” category.

*Occurs when the concentration of at least one of the contaminants used to calculate the AQI exceeds its hourly reference value at one or more of the region’s measuring stations.