SmogRank / World / Canada / Ontario / April 2024
Most polluted cities in Ontario, Canada, April 2024
28 cities in Ontario, Canada ranked by their average PM2.5 over the 30 days. Worst: Hamilton at 6.1 µg/m³, #1,620 of 2,482 cities in the world. Cleanest: Sault Ste. Marie at 2.9. 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.
- 1Hamilton 0%
- 2Windsor 0%
- 3Brantford 0%
- 3London 0%
- 5Brooklin 0%
- 6Kitchener 0%
- 7Milton 0%
- 7Toronto 0%
- 9Barrie 0%
- 9Oakville 0%
- 9St. Catharines 0%
- 12Sarnia 0%
- 13Chatham 0%
- 14Waterdown 0%
- 15Guelph 0%
- 16Brampton 0%
- 17Mississauga 0%
- 18Greater Sudbury 0%
- 18Thunder Bay 0%
- 20Newmarket 0%
- 21Kingston 0%
- 21Ottawa 0%
- 23Belleville 0%
- 23Cornwall 0%
- 25Peterborough 0%
- 26North Bay 0%
- 27Parry Sound 0%
- 27Sault Ste. Marie 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, April 2024, smogrank.com/ca/region/ontario/history/2024-04 (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.