SmogRank / United Kingdom / England / Hayes
Hayes, month by month
Hayes has a measured daily mean on 814 days since 1 January 2023. Its worst month was March 2026, at 60 US AQI (13.7 µg/m³), 981st of 2,971 cities on that month's world ranking. Its cleanest was August 2023, at 22 US AQI (3.9 µg/m³).
Every month since 2023
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
Months without a mean, and why
20 months
| Month | Why |
|---|---|
| Sep 2026 | 1 of 30 days measured; a month needs 21. The others: 29 with under 18 hours of readings or readings that failed our checks. |
| Aug 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2026 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| May 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Apr 2026 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Nov 2025 | 12 of 30 days measured; a month needs 21. The others: 18 with under 18 hours of readings or readings that failed our checks. |
| Mar 2025 | 2 of 31 days measured; a month needs 22. The others: 29 with under 18 hours of readings or readings that failed our checks. |
| Feb 2025 | No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks. |
| Jan 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Dec 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Nov 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Apr 2024 | 15 of 30 days measured; a month needs 21. The others: 15 with under 18 hours of readings or readings that failed our checks. |
| Oct 2023 | 17 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks. |
| Jul 2023 | 17 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 13 with under 18 hours of readings or readings that failed our checks. |
| Jun 2023 | 19 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| May 2023 | 18 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | 20 of 30 days measured; a month needs 21. The others: 2 missing from OpenAQ's archive, 8 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 11 of 31 days measured; a month needs 22. The others: 20 missing from OpenAQ's archive. |
| Feb 2023 | 3 of 28 days measured; a month needs 20. The others: 25 missing from OpenAQ's archive. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Hayes's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| March 2026 | 6013.7 µg/m³ | 981stof 2,971 | Europe, 18 to 25 March 2026 Europe, 1 to 12 March 2026 |
| April 2025 | 5511.3 µg/m³ | 870thof 2,951 | – |
| January 2023 | 5310.0 µg/m³ | 482ndof 1,261 | France, The Netherlands and United Kingdom, January 2023 |
| September 2023 | 519.1 µg/m³ | 775thof 2,176 | – |
| January 2026 | 519.1 µg/m³ | 1,220thof 2,617 | – |
| May 2024 | 509.0 µg/m³ | 995thof 2,684 | – |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Hayes's worst days
| Day | US AQI | Episode |
|---|---|---|
| 23 Jan 2023 | 12344.5 µg/m³ | France, The Netherlands and United Kingdom, January 2023 |
| 15 Feb 2023 | 10838.3 µg/m³ | Europe, 6 to 25 February 2023 |
| 9 Mar 2026 | 10738.1 µg/m³ | Europe, 1 to 12 March 2026 |
| 5 Mar 2026 | 9934.8 µg/m³ | Europe, 1 to 12 March 2026 |
| 24 Mar 2026 | 9331.5 µg/m³ | Europe, 18 to 25 March 2026 |
| 14 Feb 2023 | 9029.8 µg/m³ | Europe, 6 to 25 February 2023 |
| 25 Jan 2023 | 8326.2 µg/m³ | France, The Netherlands and United Kingdom, January 2023 |
| 11 Mar 2024 | 8125.1 µg/m³ | United Kingdom and The Netherlands, March 2024 |
| 26 Jan 2026 | 8024.7 µg/m³ | – |
| 7 Sept 2023 | 8024.5 µg/m³ | – |
Daily means, the highest since 1 Jan 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Hayes, United Kingdom, 1 Jan 2023 – 11 Oct 2026. Monitor data from UK-AIR (Defra), read from the publisher; sources listed at smogrank.com/sources. smogrank.com/gb/hayes/history (accessed 12 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.
Hayes now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 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 low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).