SmogRank / World / Canada / Ontario / June 2023

Most polluted cities in Ontario, Canada, June 2023

20 cities in Ontario, Canada ranked by their average PM2.5 over the 30 days. Worst: North Bay at 43.6 µg/m³, #32 of 1,549 cities in the world. Cleanest: Toronto at 17.7. 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.

← North Bay 33% 30%0
Every city in Ontario, Canada ranked for June 2023, one column each, ranked by unhealthy days: height is the share of its measured days that were unhealthy, colour its average. Point at it to read a city; tap to open it.
  1. 1North Bay
    33%
  2. 2Windsor
    30%
  3. 3Greater Sudbury
    27%
  4. 4Ottawa
    27%
  5. 5Parry Sound
    27%
  6. 6Belleville
    24%
  7. 7Sarnia
    23%
  8. 8Peterborough
    23%
  9. 9Kitchener
    23%
  10. 10Chatham
    20%
  11. 11St. Thomas
    20%
  12. 12St. Catharines
    20%
  13. 13Barrie
    20%
  14. 14Cornwall
    20%
  15. 15Brantford
    20%
  16. 16Sault Ste. Marie
    19%
  17. 17London
    17%
  18. 18Kingston
    15%
  19. 19Hamilton
    13%
  20. 20Toronto
    7%
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

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, June 2023 · All cities in Canada, June 2023 · Ontario now

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SmogRank, most polluted cities in Ontario, Canada, PM2.5, June 2023, smogrank.com/ca/region/ontario/history/2023-06 (accessed 6 Oct 2026).

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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.