SmogRank / Taiwan / Taiwan / Hengchun
Hengchun, month by month
Hengchun has a measured daily mean on 821 days since 8 February 2024. Its worst month was April 2026, at 55 US AQI (11.5 µg/m³), 762nd of 2,941 cities on that month's world ranking. Its cleanest was June 2025, at 11 US AQI (2.0 µg/m³).
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 | 6 of 29 days measured; a month needs 21. The others: 16 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.
Hengchun's worst months
| Month | US AQI | World rank |
|---|---|---|
| April 2026 | 5511.5 µg/m³ | 762ndof 2,941 |
| April 2024 | 5410.8 µg/m³ | 907thof 2,520 |
| April 2025 | 529.8 µg/m³ | 1,229thof 2,951 |
| January 2025 | 529.7 µg/m³ | 1,045thof 2,474 |
| March 2024 | 519.3 µg/m³ | 530thof 1,698 |
| January 2026 | 478.4 µg/m³ | 1,389thof 2,617 |
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.
Hengchun's worst days
| Day | US AQI |
|---|---|
| 17 Feb 2025 | 7723.0 µg/m³ |
| 4 Apr 2024 | 7622.7 µg/m³ |
| 15 Apr 2025 | 7622.4 µg/m³ |
| 9 Aug 2026 | 7421.3 µg/m³ |
| 3 Apr 2024 | 7421.2 µg/m³ |
| 23 Apr 2026 | 7321.1 µg/m³ |
| 20 Mar 2024 | 7119.8 µg/m³ |
| 16 Apr 2025 | 7019.5 µg/m³ |
| 18 Apr 2026 | 7019.5 µg/m³ |
| 4 Jan 2025 | 7019.3 µg/m³ |
Daily means, the highest since 8 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, Hengchun, Taiwan, 8 Feb 2024 – 12 Oct 2026. Monitor data from Taiwan's Ministry of Environment via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/tw/hengchun/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.
Hengchun 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).