SmogRank / World / Europe / United Kingdom / Wales
Most polluted cities in Wales, United Kingdom
4 measured cities, last 7 days; 0 above the WHO 24-hour guideline. Worst: Swansea at 6.1 µg/m³, #1,615 in the world.
Now: cities by their PM2.5 over the last 24 hours; fires, smoke and ash from Oct 7, the newest day mapped.
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
Estimated: cities without a monitor
Wales cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.
| City | 7-day estimate |
|---|---|
| Rhondda | ≈ 3 µg/m³ |
| Buckley | ≈ 3 µg/m³ |
| Tonypandy | ≈ 3 µg/m³ |
| Barry | ≈ 3 µg/m³ |
| Bridgend | ≈ 3 µg/m³ |
| Llanelli | ≈ 3 µg/m³ |
| Cwmbran | ≈ 4 µg/m³ |
| Neath | ≈ 3 µg/m³ |
| Merthyr Tydfil | ≈ 4 µg/m³ |
| Coity | ≈ 3 µg/m³ |
| Pontypool | ≈ 4 µg/m³ |
| Briton Ferry | ≈ 3 µg/m³ |
| Ebbw Vale | ≈ 4 µg/m³ |
| Deeside | ≈ 3 µg/m³ |
| Pontypridd | ≈ 4 µg/m³ |
| Aberdare | ≈ 3 µg/m³ |
| Caerphilly | ≈ 4 µg/m³ |
| Colwyn Bay | ≈ 3 µg/m³ |
| Flint | ≈ 3 µg/m³ |
| Rhyl | ≈ 3 µg/m³ |
| Hawarden | ≈ 3 µg/m³ |
| Rhosllannerchrugog | ≈ 3 µg/m³ |
| Ammanford | ≈ 3 µg/m³ |
| Penarth | ≈ 3 µg/m³ |
| Maesteg | ≈ 3 µg/m³ |
| Gorseinon | ≈ 3 µg/m³ |
| Risca | ≈ 4 µg/m³ |
| Clydach | ≈ 3 µg/m³ |
| Prestatyn | ≈ 3 µg/m³ |
| Aberystwyth | ≈ 3 µg/m³ |
| Bangor | ≈ 3 µg/m³ |
| Brymbo | ≈ 3 µg/m³ |
| Gelligaer | ≈ 4 µg/m³ |
| Carmarthen | ≈ 4 µg/m³ |
| Porthcawl | ≈ 3 µg/m³ |
| Blackwood | ≈ 4 µg/m³ |
| Llandudno | ≈ 3 µg/m³ |
Bad-air episodes in Wales
- Europe, 18 to 25 March 20268 days430 cities136 µg/m³peak, Łask
- Europe, 1 to 12 March 202612 days532 cities109 µg/m³peak, Radomsko
- United Kingdom, Belgium and 2 more countries, June 202311 to 12 June 2023, 2 days13 cities37 µg/m³peak, Bexley
- Europe, 6 to 25 February 202320 days647 cities137 µg/m³peak, Banja Luka
- France, The Netherlands and United Kingdom, January 202321 to 25 January 2023, 5 days72 cities52 µg/m³peak, Tilburg
Times when many cities around here had PM2.5 at twice their usual or more on the same days.
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SmogRank, most polluted cities in Wales, United Kingdom, PM2.5, last 7 days to 8 Oct 2026, 21:00 UTC, smogrank.com/gb/region/wales?w=7d. Some readings from Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); Love My Air (City and County of Denver), no reuse terms published.
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.
Updated 2026-10-08 21:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); Love My Air (City and County of Denver), no reuse terms published (why we use them).