Markham AQI Trends
Markham AQI was measured across 2024-2025, with a trend delta of n/a AQI points. The page uses OpenAQ-derived daily history for 1 mapped monitoring location in Ontario, Canada.
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Average EPA AQI
45
Rank 7 of 158 cities by average AQI
PM2.5
11.2
ug/m3 annualized city average
Seasonality
September
Cleanest: November
Health indicator
0.5
cigarette-equivalent per day
Yearly EPA AQI trend
Seasonal EPA AQI heatmap
JanFebMarAprMayJunJulAugSepOctNovDec
Markham
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59
42
34
51
What this trends page measures
Compare yearly air-quality direction, best years, worst years, and trend deltas.
For Markham, the current global analytics build covers 112 daily rows from 2024-09-12 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.