SmogRank / World / Europe / United Kingdom / Wales
Most polluted cities in Wales, United Kingdom
6 measured cities, last 24 hours; 0 above the WHO 24-hour guideline. Worst: Swansea at 6.9 µg/m³, #260 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 | ≈ 4 µg/m³ |
| Buckley | ≈ 4 µg/m³ |
| Tonypandy | ≈ 4 µg/m³ |
| Barry | ≈ 5 µg/m³ |
| Bridgend | ≈ 4 µg/m³ |
| Llanelli | ≈ 5 µg/m³ |
| Cwmbran | ≈ 4 µg/m³ |
| Neath | ≈ 5 µg/m³ |
| Merthyr Tydfil | ≈ 4 µg/m³ |
| Coity | ≈ 4 µg/m³ |
| Pontypool | ≈ 4 µg/m³ |
| Briton Ferry | ≈ 5 µg/m³ |
| Ebbw Vale | ≈ 4 µg/m³ |
| Deeside | ≈ 4 µg/m³ |
| Pontypridd | ≈ 4 µg/m³ |
| Aberdare | ≈ 4 µg/m³ |
| Caerphilly | ≈ 4 µg/m³ |
| Colwyn Bay | ≈ 4 µg/m³ |
| Flint | ≈ 4 µg/m³ |
| Rhyl | ≈ 4 µg/m³ |
| Hawarden | ≈ 4 µg/m³ |
| Rhosllannerchrugog | ≈ 4 µg/m³ |
| Ammanford | ≈ 5 µg/m³ |
| Penarth | ≈ 4 µg/m³ |
| Maesteg | ≈ 4 µg/m³ |
| Gorseinon | ≈ 5 µg/m³ |
| Risca | ≈ 4 µg/m³ |
| Clydach | ≈ 5 µg/m³ |
| Prestatyn | ≈ 4 µg/m³ |
| Aberystwyth | ≈ 4 µg/m³ |
| Bangor | ≈ 4 µg/m³ |
| Brymbo | ≈ 4 µg/m³ |
| Gelligaer | ≈ 4 µg/m³ |
| Carmarthen | ≈ 5 µg/m³ |
| Porthcawl | ≈ 4 µg/m³ |
| Blackwood | ≈ 4 µg/m³ |
| Llandudno | ≈ 4 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.
Use this board
SmogRank, most polluted cities in Wales, United Kingdom, PM2.5, last 24 hours to 8 Oct 2026, 20:00 UTC, smogrank.com/gb/region/wales. 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 20:07 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).