SmogRank / Mexico / Guanajuato / León de los Aldama
León de los Aldama, month by month
León de los Aldama has a measured daily mean on 1,040 days since 1 January 2023. Its worst month was May 2023, at 83 US AQI (26.5 µg/m³), 69th of 1,600 cities on that month's world ranking. Its cleanest was August 2023, at 54 US AQI (10.7 µg/m³). 2025 averaged 66 US AQI (17.2 µg/m³), against 65 US AQI (16.7 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
10 months
| Month | Why |
|---|---|
| Feb 2026 | 17 of 28 days measured; a month needs 20. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Aug 2025 | 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 2025 | 18 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Jan 2025 | 13 of 31 days measured; a month needs 22. The others: 18 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 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jul 2024 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Jun 2024 | 11 of 30 days measured; a month needs 21. The others: 19 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.
León de los Aldama's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| May 2023 | 8326.5 µg/m³ | 69thof 1,600 | – |
| May 2024 | 8024.7 µg/m³ | 95thof 2,684 | – |
| November 2024 | 7823.7 µg/m³ | 135thof 2,624 | – |
| December 2024 | 7723.1 µg/m³ | 173rdof 2,616 | Guanajuato, México and Mexico City, Mexico, December 2024 |
| January 2023 | 7622.6 µg/m³ | 115thof 1,261 | – |
| May 2025 | 7320.9 µg/m³ | 251stof 2,826 | – |
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 de los Aldama's worst days
| Day | US AQI | Episode |
|---|---|---|
| 1 Jan 2026 | 15460.4 µg/m³ | Southern Mexico, January 2026 |
| 1 Jan 2024 | 14151.9 µg/m³ | Southern Mexico, January 2024 |
| 21 May 2025 | 12143.6 µg/m³ | – |
| 25 Dec 2024 | 11742.2 µg/m³ | Guanajuato, México and Mexico City, Mexico, December 2024 |
| 4 May 2023 | 11541.1 µg/m³ | – |
| 16 May 2023 | 11340.4 µg/m³ | – |
| 31 Dec 2024 | 11340.4 µg/m³ | – |
| 5 May 2023 | 11139.6 µg/m³ | – |
| 25 Dec 2023 | 11139.6 µg/m³ | Southern Mexico, December 2023 |
| 29 Apr 2025 | 11139.5 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, León de los Aldama, Mexico, 1 Jan 2023 – 11 Oct 2026. Monitor data from Sinaica Mexico via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/mx/leon-de-los-aldama/history (accessed 13 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 de los Aldama now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 01:07 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).