Markham Health Impact
Markham averaged 11.2 ug/m3 PM2.5, equal to 2.2x the WHO annual PM2.5 guideline and about 0.5 cigarettes per day by the simple AQI Now indicator. 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 health page measures
Translate PM2.5 exposure into WHO exceedance and a simple cigarette-equivalent indicator.
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.