Air Quality Monitoring Stations - Monthly Results Sample Table

How do I read the monthly results?

The monthly results provide the concentration of each monitored pollutant in the air, for every day of the month, for the intervals at which they are recorded.

All pollutants are measured continuously, but reported using multiple time intervals, dependant on the pollutant. Any time the concentration of a pollutant in the air exceeds the stated threshold (acceptable maximum concentration), it is marked with an asterix (*).

In the excerpt below from the January 2016 report for Île-des-Sœurs, you can see that on January 8, the threshold for fine particulate matter was exceeded for a 3 hour period by 4 micrograms per cubic metre.

Sample Table: Île-des-Soeurs Particle Pollution Report for January 2016
Pollutant PMTOT PM2.5
Time 1h 8h 24h 3h 24h
Threshold

300 µg/m3

190 µg/m3

120 µg/m3

35 µg/m3

30 µg/m3

06-January

103

82

51

22

15

07-January

200

136

83

35

20

08-January

65

72

42

39*

29

Air Quality Table Definitions

  • PMTOT: Total airborne particles, in solid or liquid form
  • PM2.5: Fine airborne particulate matter
  • Time: Indicates the highest concentration of the pollutant, over a defined time period, based on data collected during the entire day. For example, if the concentration of fine particles is highest between 6-9 am, the data under the 3 hr column represents the average concentration for this interval.
  • Threshold: Indicates the maximum acceptable concentration of the pollutant in the air measured in micrograms per cubic metre. Thresholds are based on municipal and provincial legislation and other references.
  • Asterix (*): Indicates that the reading on this day exceeded the stated threshold.
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