SmogRank / World / Canada / Quebec / September 2025

Most polluted cities in Quebec, Canada, September 2025

17 cities in Quebec, Canada ranked by their average PM2.5 over the 30 days. Worst: Sorel-Tracy at 6.8 µg/m³, #1,717 of 3,052 cities in the world. Cleanest: Saint-Jean-sur-Richelieu at 3.9. 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.

← Sorel-Tracy 0% 0.75%0

Every city in Quebec, Canada ranked for September 2025, 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.

1Sorel-Tracy
0%
2Montréal
0%
3Dorval
0%
4Brossard
0%
4Granby
0%
4Rivière-des-Prairies–Pointe-aux-Trembles
0%
7Trois-Rivières
0%
7Québec
0%
9L'Ancienne-Lorette
0%
10Shawinigan
0%
11Drummondville
0%
12Bécancour
0%
12Saguenay
0%
14Sherbrooke
0%
15Sept-Îles
0%
16Rouyn-Noranda
0%
17Saint-Jean-sur-Richelieu
0%

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, September 2025 · All cities in Canada, September 2025 · Quebec now

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SmogRank, most polluted cities in Quebec, Canada, PM2.5, September 2025, smogrank.com/ca/region/quebec/history/2025-09 (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.