SmogRank / Chile / Los Ríos Region / La Unión
La Unión, month by month
La Unión has a measured daily mean on 1,155 days since 1 January 2023. Its worst month was May 2024, at 161 US AQI (69.4 µg/m³), 13th of 2,684 cities on that month's world ranking. Its cleanest was January 2023, at 59 US AQI (13.3 µg/m³). 2025 averaged 93 US AQI (31.7 µg/m³), against 99 US AQI (34.6 µg/m³) in 2024.
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
7 months
| Month | Why |
|---|---|
| Oct 2025 | 14 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks. |
| Sep 2025 | 10 of 30 days measured; a month needs 21. The others: 20 with under 18 hours of readings or readings that failed our checks. |
| Mar 2025 | 20 of 31 days measured; a month needs 22. The others: 11 with under 18 hours of readings or readings that failed our checks. |
| Feb 2025 | 18 of 28 days measured; a month needs 20. The others: 10 with under 18 hours of readings or readings that failed our checks. |
| Jan 2025 | 21 of 31 days measured; a month needs 22. The others: 10 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.
La Unión's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| May 2024 | 16169.4 µg/m³ | 13thof 2,684 | South-western Chile, 24 to 28 May 2024 South-western Chile, 14 to 19 May 2024 |
| July 2024 | 15560.7 µg/m³ | 20thof 2,566 | Chile, July 2024 |
| July 2026 | 15358.7 µg/m³ | 18thof 2,784 | Southern Chile, July 2026 |
| May 2026 | 15155.9 µg/m³ | 39thof 2,874 | Chile, May 2026 Southern Chile, May 2026 |
| August 2024 | 15155.8 µg/m³ | 10thof 2,010 | South-western Chile, 18 to 20 August 2024 Southern Chile, 12 to 13 August 2024and 1 more |
| June 2026 | 14352.7 µg/m³ | 39thof 2,497 | – |
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.
La Unión's worst days
| Day | US AQI | Episode |
|---|---|---|
| 5 Jul 2026 | 276201.0 µg/m³ | Southern Chile, July 2026 |
| 6 Jul 2026 | 230155.0 µg/m³ | Southern Chile, July 2026 |
| 3 Jul 2026 | 224149.0 µg/m³ | Southern Chile, July 2026 |
| 30 Jun 2025 | 217142.0 µg/m³ | Southern Chile, 29 June to 4 July 2025 |
| 17 May 2024 | 215140.0 µg/m³ | South-western Chile, 14 to 19 May 2024 |
| 4 Jul 2026 | 213138.0 µg/m³ | Southern Chile, July 2026 |
| 26 May 2024 | 202127.0 µg/m³ | South-western Chile, 24 to 28 May 2024 |
| 1 Jul 2025 | 196120.0 µg/m³ | Southern Chile, 29 June to 4 July 2025 |
| 18 Jul 2023 | 195118.0 µg/m³ | Southern Chile, July 2023 |
| 16 May 2024 | 193116.0 µg/m³ | South-western Chile, 14 to 19 May 2024 |
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, La Unión, Chile, 1 Jan 2023 – 11 Oct 2026. Monitor data from Chile - SINCA via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/cl/la-union/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.
La Unión now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 22:07 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).