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2013 annual air quality index statistics—by sector

Air quality varied considerably across the 17 urban sectors for which the AQI is calculated. In 2013, the percentage of days when air quality was “poor” ranged from 1% in Sherbrooke (Eastern sector) to 31% in Sorel-Tracy (Saint-Joseph-de-Sorel sector).

In comparison with 2012, the average number of days—all sectors combined—where air quality was deemed “good” or “acceptable” increased by 2%, reaching 89%. The average number of days of “poor*” air quality decreased by 2% and is now at 11%. Despite these slight variations, the AQI statistics per sector for 2013 remain similar to what has been 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 a 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.

* Occurs when the concentration of at least one of the pollutants used to calculate the AQI is greater than its reference value.


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