Ministère de l'Environnement
et de la Lutte contre les changements climatiques

2019 Annual Regional Air Quality Index Statistics

The Air Quality Index (AQI) was calculated in 2019 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 89% for Montréal (324/365) to 100% for the Témiscouata, Rivière-du-Loup, Lac-Saint-Jean, Montmagny, Laurentides, Vaudreuil-Huntingdon and Lachute regions.

Montréal was where air quality was most often “poor*,” with a proportion of 11% (41/365 days). This result varied little compared with the 2018 figure of 9%.

In overall terms, the respective AQI “good,” “acceptable” and “poor” proportions were 62%, 37% and 2%. Compared to 2018, the “good” proportion of results increased by 9%, with the gain coming from a decrease in the “acceptable” 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.

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