ozone O3:

Ontario's ambient air monitoring stations

ozone O3 Concentrations for Friday, July 18, 2025, 7:00 pm

Note: The pollutant concentrations on this web page are based on automatically polled data and have not undergone final verification.

Note: N/A (not available) denotes invalid or missing data.
Ontario 1-hour AAQC for O3 = 80 ppb