The provincial air quality objective for coarse particles, PM₁₀, is 50 micrograms per cubic metre, averaged over 24 hours. The 24 hour PM₁₀ rolling average was 57 µg/m³ at the Plaza 400 downtown, 56 µg/m³ at BCR and 25 µg/m³ at College Heights at 7 am today. 

The provincial air quality objective for fine particles, PM_2.5, is 25 micrograms per cubic metre, averaged over 24 hours. The 24 hour PM_2.5 rolling average was 14 µg/m³ at the Plaza 400 downtown site and 10 µg/m³ at College Heights at 7 am today.

Based on the air quality data, the high levels are mainly due to road dust, as well as emissions from industry and transportation sources such as automobiles, trucks and rail traffic. 

An upper high pressure ridge has brought stagnant conditions over the region resulting in pollutants accumulating in the air shed. This ridge will slowly move eastward in the next 24-hours.

This episode is expected to continue at least until tomorrow morning.