Annual sector air quality index statistics for 2011

Air quality varied considerably across the 17 urban sectors in which the AQI is calculated. In 2011, the percentage of days when air quality was “poor” ranged from 2% in Trois-Rivières, in the Sanctuary sector, to 33% in Témiscaming.

Looking at all sectors combined, the total number of days when air quality was “poor*” remained stable as compared to the previous year, while the number of days when air quality was “good” fell by 4%. The number of days when air quality was “acceptable” increased by 5%. From 2010 to 2011, the greatest improvement in air quality was in the Saint-Joseph-de-Sorel sector in Sorel-Tracy. Despite these variations, the AQI sector statistics for 2011 are similar to those observed since 2004.

It is important to note that unlike regional statistics, which are based on uniform measurements of fine particulate matter and ozone, sector statistics may include measurements of a pollutant emitted locally that is not detected at the regional level. As a result, the AQI value for a particular sector may be different from that of its region.

Local sources of atmospheric emissions affecting a sector’s AQI can vary from one location to another.

* 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.