SmogRank / World / Canada / Ontario / January 2024
Most polluted cities in Ontario, Canada, January 2024
29 cities in Ontario, Canada ranked by their average PM2.5 over the 31 days. Worst: Windsor at 10.8 µg/m³, #802 of 2,341 cities in the world. Cleanest: Parry Sound at 4.3. A city needs measurements on 70% of the days to be ranked.
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%
- 2London 0%
- 3Waterdown 0%
- 4Brantford 0%
- 5Hamilton 0%
- 6Chatham 0%
- 6Milton 0%
- 6Oakville 0%
- 6Sarnia 0%
- 6Toronto 0%
- 11St. Thomas 0%
- 12Kitchener 0%
- 13Guelph 0%
- 14Mississauga 0%
- 15Brampton 0%
- 16St. Catharines 0%
- 17Barrie 0%
- 17Cornwall 0%
- 17Newmarket 0%
- 20Peterborough 0%
- 21Brooklin 0%
- 22Ottawa 0%
- 23Belleville 0%
- 24Kingston 0%
- 25Greater Sudbury 0%
- 26Thunder Bay 0%
- 27Sault Ste. Marie 0%
- 28North Bay 0%
- 28Parry 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, January 2024 · All cities in Canada, January 2024 · Ontario now
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SmogRank, most polluted cities in Ontario, Canada, PM2.5, January 2024, smogrank.com/ca/region/ontario/history/2024-01 (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.