Air Quality Index Statistics
The annual statistical portraits indicate the percentage and number of
days and hours during which the Air Quality Index (AQI) is “good”,
“acceptable” or “poor”. AQI hourly values correspond to hourly observations,
while daily values are taken from the maximum hourly AQI of the day.
Overall Annual Summary
Detailed Annual Summary (french)
Quality Control and Assurance of the data
The MDDEFP’s quality control and assurance processes were
followed closely while compiling the data for these summaries. However,
since these processes are regularly improved and updated, slight adjustments
may have been made to the data hereby presented. Note that the summaries
include the island of Montréal, which is divided into four subregions.
Measurement of Fine Particles Matter
Under the Air Quality Monitoring Program, a new generation
of fine particulate matter measurement instruments has been deployed
throughout the monitoring network. The effects of this upgrade have been
apparent since 2008 for the island of Montréal, and since 2009 for other
regions. This equipment upgrade is one of the reasons for some of the higher
readings recorded as compared to prior years. The increase should not be
systematically interpreted as air quality deterioration.