By Sara Sears, CBC News Ottawa, February 10, 2022
...Two volunteer-run projects — one operated by the Sierra Club Canada — regularly sample air quality across Ottawa. Monitoring is suspended during the protest for safety reasons, but CBC News borrowed one of the monitors' devices to gather air quality data. The devices test for several pollutant particles, including PM 2.5.
CBC News took various air quality measures around the downtown core near where trucks and other vehicles were parked and idling. Measurements for PM 2.5 ranged from four to eight times higher than normal for the area.