SmogRank / Spain / Castille and León / León
León, month by month
León, Castille and León has a measured daily mean on 912 days since 11 January 2023. Its worst month was August 2025, at 83 US AQI (26.5 µg/m³), 112th of 2,901 cities on that month's world ranking. Its cleanest was July 2023, at 25 US AQI (4.5 µg/m³). 2025 averaged 48 US AQI (8.7 µg/m³), against 44 US AQI (8.0 µg/m³) in 2023.
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
21 months
| Month | Why |
|---|---|
| Oct 2026 | 6 of 11 days measured; a month needs 8. The others: 3 with no readings from the monitor, 2 with readings for part of the day (a day needs 18 hours). |
| Sep 2026 | 14 of 30 days measured; a month needs 21. The others: 16 with readings for part of the day (a day needs 18 hours). |
| Aug 2026 | 21 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks. |
| Jul 2026 | 19 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Jun 2026 | 6 of 30 days measured; a month needs 21. The others: 24 with under 18 hours of readings or readings that failed our checks. |
| May 2026 | 1 of 31 days measured; a month needs 22. The others: 30 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. |
| Mar 2026 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Feb 2026 | 8 of 28 days measured; a month needs 20. The others: 20 with under 18 hours of readings or readings that failed our checks. |
| Mar 2025 | 18 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks. |
| Feb 2025 | 17 of 28 days measured; a month needs 20. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Dec 2024 | 19 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Oct 2024 | 15 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Sep 2024 | No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks. |
| Aug 2024 | 6 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks. |
| Jul 2024 | 12 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks. |
| Mar 2024 | 15 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks. |
| Aug 2023 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Apr 2023 | 3 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks. |
| Mar 2023 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Jan 2023 | 7 of 31 days measured; a month needs 22. The others: 14 with under 18 hours of readings or readings that failed our checks. |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
León's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| August 2025 | 8326.5 µg/m³ | 112thof 2,901 | Northern Spain, August 2025 Spain, Portugal and Andorra, August 2025 |
| January 2024 | 6114.2 µg/m³ | 520thof 2,385 | Spain, France and 2 more countries, December 2023 to January 2024 |
| December 2023 | 6014.0 µg/m³ | 314thof 2,247 | Spain, France and 2 more countries, December 2023 to January 2024 |
| February 2023 | 5813.1 µg/m³ | 472ndof 1,129 | – |
| February 2024 | 5712.4 µg/m³ | 445thof 2,486 | Spain, Portugal and France, February 2024 |
| January 2025 | 5410.5 µg/m³ | 909thof 2,474 | – |
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.
León's worst days
| Day | US AQI | Episode |
|---|---|---|
| 17 Aug 2025 | 201126.0 µg/m³ | Spain, Portugal and Andorra, August 2025 |
| 18 Aug 2025 | 190111.0 µg/m³ | Spain, Portugal and Andorra, August 2025 |
| 19 Aug 2025 | 15764.3 µg/m³ | Spain, Portugal and Andorra, August 2025 |
| 26 Aug 2025 | 15560.7 µg/m³ | Northern Spain, August 2025 |
| 13 Aug 2025 | 14051.3 µg/m³ | Spain, Portugal and Andorra, August 2025 |
| 12 Aug 2025 | 13750.3 µg/m³ | Spain, Portugal and Andorra, August 2025 |
| 17 Dec 2025 | 10738.0 µg/m³ | – |
| 16 Aug 2025 | 9934.8 µg/m³ | Spain, Portugal and Andorra, August 2025 |
| 2 Feb 2024 | 9231.1 µg/m³ | Spain, Portugal and France, February 2024 |
| 1 Feb 2024 | 9030.3 µg/m³ | Spain, Portugal and France, February 2024 |
Daily means, the highest since 11 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, León, Castille and León, Spain, 11 Jan 2023 – 8 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/es/leon/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.
León now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 17:07 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).