SmogRank / World / Ireland / Connacht / September 2026
Most polluted cities in Connacht, Ireland, September 2026
2 cities in Connacht, Ireland ranked by their average PM2.5 over the 30 days. Worst: Galway at 6.3 µg/m³, #1,548 of 2,949 cities in the world. Cleanest: Sligo at 5.7. 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.
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 2026 · All cities in Ireland, September 2026 · Connacht now
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SmogRank, most polluted cities in Connacht, Ireland, PM2.5, September 2026, smogrank.com/ie/region/connacht/history/2026-09 (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.