SmogRank / Taiwan / Taiwan / Yuanlin
Yuanlin, month by month
Yuanlin has a measured daily mean on 813 days since 28 February 2024. Its worst month was March 2024, at 78 US AQI (23.6 µg/m³), 105th of 1,698 cities on that month's world ranking. Its cleanest was July 2024, at 49 US AQI (8.8 µg/m³). 2025 averaged 66 US AQI (17.3 µg/m³), against 63 US AQI (15.3 µg/m³) in 2024.
Every month since 2024
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
5 months
| Month | Why |
|---|---|
| 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. |
| Oct 2025 | 10 of 31 days measured; a month needs 22. The others: 21 with under 18 hours of readings or readings that failed our checks. |
| Aug 2025 | 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 2025 | No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks. |
| Feb 2024 | 1 of 29 days measured; a month needs 21. The others: 1 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.
Yuanlin's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| March 2024 | 7823.6 µg/m³ | 105thof 1,698 | – |
| February 2026 | 7722.9 µg/m³ | 447thof 2,866 | – |
| April 2025 | 7421.5 µg/m³ | 296thof 2,951 | – |
| January 2025 | 7421.2 µg/m³ | 258thof 2,474 | Taiwan, 21 to 22 January 2025 |
| March 2026 | 7321.0 µg/m³ | 569thof 2,971 | – |
| April 2024 | 7220.4 µg/m³ | 220thof 2,520 | – |
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.
Yuanlin's worst days
| Day | US AQI | Episode |
|---|---|---|
| 22 Jan 2025 | 15055.3 µg/m³ | Taiwan, 21 to 22 January 2025 |
| 11 Mar 2025 | 11440.7 µg/m³ | – |
| 16 Mar 2024 | 11239.8 µg/m³ | – |
| 6 Feb 2025 | 11139.4 µg/m³ | – |
| 15 Nov 2024 | 10537.0 µg/m³ | Taiwan, November 2024 |
| 21 Feb 2026 | 10436.7 µg/m³ | – |
| 11 Apr 2024 | 10436.6 µg/m³ | – |
| 14 Nov 2024 | 10336.4 µg/m³ | Taiwan, November 2024 |
| 13 Feb 2026 | 10336.4 µg/m³ | – |
| 4 Mar 2024 | 10236.0 µg/m³ | – |
Daily means, the highest since 28 Feb 2024; 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, Yuanlin, Taiwan, 28 Feb 2024 – 12 Oct 2026. Monitor data from Taiwan's Ministry of Environment via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/tw/yuanlin/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.
Yuanlin 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).