Air Quality Index Statistics
Annual statistics display information according a percentage and the
number of days and hours the air quality index (AQI) is “good”,
“acceptable” or “poor”. Hourly observations correspond to AQI hourly
values, while daily values are determined by the maximum hourly AQI
observation during the day.
Usually, when the air quality index is “poor”, this is attributable
to the presence of fine particles.
| Please note that the 2010 annual IQA statistics are currently being generated and will be posted online shortly.
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Overall Annual Summary
Detailed Annual Summary (french)
Control and Quality of Data
The data that are used to compile these summaries were
obtained by following each phase of the quality control and assurance
process. Some information may change over time, however, due to improvements
to quality control processes. These summaries include the Montréal Island,
which is divided into four subregions.
Measurement of Fine Particles
In keeping with the Air quality monitoring program, a new
generation of instruments is used to measure fine particles throughout the
monitoring network. The effect of this change has been discernable since
2008 for the Montréal Island and since 2009 for other regions. It is one of
the factors that is largely accountable for an increase in the AQI.
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