Cardiff vs Newport: PM2.5 compared
Over the last year, Cardiff's air was 31% more polluted than Newport's: PM2.5 averaged 9.3 µg/m³ against 7.1, on the 138 days both cities were measured. Cardiff had the dirtier air on 132 of those days, Newport on 5. Cardiff was over the WHO's daily guideline of 15 µg/m³ on 8 of them, Newport on 8.
Right now
The last year, day by day
Month by month
Year by year
| Year | Cardiff | Newport | Days Cardiff was worse |
|---|---|---|---|
| 2026 so far | 52 | 41 | 81 |
| 2025 | 45 | 34 | 146 |
| 2024 | 43 | 37 | 190 |
| 2023 | 55 | 42 | 191 |
Means in US AQI over the days both cities were measured that year; a year shows once they share 30 such days.
Each city's worst days
Cardiff
- 9 Mar 20269432.0 µg/m³
- 21 Mar 20268226.0 µg/m³
- 5 Mar 20268225.5 µg/m³
Newport
- 9 Mar 20268628.0 µg/m³
- 21 Mar 20268125.1 µg/m³
- 20 Mar 20267622.4 µg/m³
Daily means in US AQI, with µg/m³ beside them, since the index stops at its top value, over the days both cities were measured in the last year. Each date opens that day's world board.
Compare either city with another
Cardiff
Side by side with London (United Kingdom's worst on 30 days), Gujranwala (the world's worst on 30 days).
Newport
Side by side with London (United Kingdom's worst on 30 days), Gujranwala (the world's worst on 30 days).
Use this page
SmogRank, PM2.5 daily means compared, Cardiff and Newport, 8 Oct 2025 – 7 Oct 2026, smogrank.com/compare/gb-cardiff/gb-newport (accessed 8 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.
The same rules as every SmogRank figure: reference monitors first, and a day counts with 18 measured hours. How we measure.
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).