SmogRank / World / Canada / Ontario / August 2023
Most polluted cities in Ontario, Canada, August 2023
29 cities in Ontario, Canada ranked by their average PM2.5 over the 31 days. Worst: Greater Sudbury at 13.8 µg/m³, #210 of 1,926 cities in the world. Cleanest: Brooklin at 7.4. 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.
- 1Greater Sudbury 6%
- 2North Bay 6%
- 3Oakville 3%
- 4Barrie 3%
- 5Newmarket 3%
- 6Parry Sound 3%
- 7London 0%
- 8Windsor 0%
- 9Milton 0%
- 10Hamilton 0%
- 10St. Thomas 0%
- 12Kitchener 0%
- 13Brantford 0%
- 14Guelph 0%
- 14Waterdown 0%
- 16Brampton 0%
- 16Mississauga 0%
- 18Sarnia 0%
- 18Toronto 0%
- 20Chatham 0%
- 21St. Catharines 0%
- 22Peterborough 0%
- 23Thunder Bay 0%
- 24Ottawa 0%
- 25Sault Ste. Marie 0%
- 26Cornwall 0%
- 27Kingston 0%
- 28Belleville 0%
- 29Brooklin 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
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SmogRank, most polluted cities in Ontario, Canada, PM2.5, August 2023, smogrank.com/ca/region/ontario/history/2023-08 (accessed 6 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.