SmogRank / World / United Kingdom / Northern Ireland / September 2025
Most polluted cities in Northern Ireland, United Kingdom, September 2025
2 cities in Northern Ireland, United Kingdom ranked by their average PM2.5 over the 30 days. Worst: Belfast at 4.5 µg/m³, #2,753 of 3,052 cities in the world. Cleanest: Derry at 2.2. A city needs measurements on 70% of the days to be ranked.
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 United Kingdom, September 2025 · Northern Ireland now
Use this board
SmogRank, most polluted cities in Northern Ireland, United Kingdom, PM2.5, September 2025, smogrank.com/gb/region/northern-ireland/history/2025-09 (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.