2013 annual air quality statistics—by region

In 2013, the AQI was calculated for 24 weather regions, with the region of Montréal divided in four subregions.

The percentage of days when the AQI was deemed “good” or “acceptable” ranged from 84% in Montreal (approximately 311 days out of 365) to nearly 100% in Haute-Gatineau, La Tuque, Témiscamingue, Abitibi and Estrie (only one episode of poor air quality occurred in these regions).

Air quality was deemed “poor” most often in Montreal, in a proportion of 16% (57 days out of 365), which is an improvement compared to the previous year: air quality was “poor” 19% of the time in 2012 (70 days out of 360).

Overall, air quality was “good”, “acceptable”, or “poor” in the following proportions, respectively: 53%, 44%, and 3%. Compared to 2012, “acceptable” AQI slightly increased—by 1%—while the proportion of “good” AQI diminished.

* Air quality is deemed “poor” when at least one station in the region reports a concentration of fine particulate matter greater than 35 µg/m3 (over a three-hour period), or an hourly concentration of ozone greater than 82 ppb.