Toronto Seasonal Pollution
Toronto usually records its highest OpenAQ-derived EPA AQI in May and its cleanest month in December. The page uses OpenAQ-derived daily history for 3 mapped monitoring locations in Ontario, Canada.
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Average EPA AQI
35
Rank 41 of 158 cities by average AQI
PM2.5
7.1
ug/m3 annualized city average
Seasonality
May
Cleanest: December
Health indicator
0.3
cigarette-equivalent per day
Yearly EPA AQI trend
Seasonal EPA AQI heatmap
JanFebMarAprMayJunJulAugSepOctNovDec
Toronto
37
36
29
32
60
34
44
42
34
29
25
25
What this seasonality page measures
Find each city's worst and cleanest months from daily OpenAQ-derived EPA AQI.
For Toronto, the current global analytics build covers 367 daily rows from 2024-01-01 to 2025-01-01. The calculations normalize PM2.5 and PM10 observations into US EPA AQI bands so country, city, and tool pages use one consistent method.