SmogRank / World / Canada / Ontario / March 2024
Most polluted cities in Ontario, Canada, March 2024
29 cities in Ontario, Canada ranked by their average PM2.5 over the 31 days. Worst: Windsor at 7.6 µg/m³, #827 of 1,643 cities in the world. Cleanest: Parry Sound at 3.3. A city needs measurements on 70% of the days to be ranked.
OpenAQ's archive, where our readings come from, has almost none from Canada for March 20, 2024: cities in Canada are averaged over their other days. Why.
Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.
- 1Windsor 0%
- 2Hamilton 0%
- 3Toronto 0%
- 4London 0%
- 5Brooklin 0%
- 6Chatham 0%
- 7Barrie 0%
- 7Brantford 0%
- 9Kitchener 0%
- 10Guelph 0%
- 10Milton 0%
- 10Sarnia 0%
- 10St. Thomas 0%
- 14Oakville 0%
- 14Thunder Bay 0%
- 14Waterdown 0%
- 17Brampton 0%
- 17Cornwall 0%
- 17St. Catharines 0%
- 20Mississauga 0%
- 20Ottawa 0%
- 22Newmarket 0%
- 23Peterborough 0%
- 24Greater Sudbury 0%
- 25Sault Ste. Marie 0%
- 26Belleville 0%
- 27North Bay 0%
- 28Kingston 0%
- 29Parry Sound 0%
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
All cities in the world, March 2024 · All cities in Canada, March 2024 · Ontario now
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SmogRank, most polluted cities in Ontario, Canada, PM2.5, March 2024, smogrank.com/ca/region/ontario/history/2024-03 (accessed 7 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.