SmogRank / Taiwan / Taiwan / Hualien City
Hualien City, month by month
Hualien City has a measured daily mean on 835 days since 8 February 2024. Its worst month was April 2024, at 63 US AQI (15.8 µg/m³), 372nd of 2,520 cities on that month's world ranking. Its cleanest was July 2024, at 18 US AQI (3.2 µg/m³). 2025 averaged 41 US AQI (7.4 µg/m³), against 43 US AQI (7.7 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 | 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.
Hualien City's worst months
| Month | US AQI | World rank |
|---|---|---|
| April 2024 | 6315.8 µg/m³ | 372ndof 2,520 |
| March 2024 | 5913.6 µg/m³ | 234thof 1,698 |
| April 2026 | 5712.4 µg/m³ | 702ndof 2,941 |
| April 2025 | 5511.5 µg/m³ | 832ndof 2,951 |
| May 2024 | 5511.2 µg/m³ | 567thof 2,684 |
| January 2025 | 5310.2 µg/m³ | 960thof 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.
Hualien City's worst days
| Day | US AQI |
|---|---|
| 13 Apr 2025 | 9734.0 µg/m³ |
| 4 Apr 2024 | 8627.9 µg/m³ |
| 8 Mar 2024 | 7823.7 µg/m³ |
| 17 Feb 2025 | 7823.7 µg/m³ |
| 20 Mar 2024 | 7723.0 µg/m³ |
| 28 Nov 2025 | 7622.7 µg/m³ |
| 11 Apr 2026 | 7622.6 µg/m³ |
| 23 Apr 2024 | 7522.0 µg/m³ |
| 3 Apr 2024 | 7421.6 µg/m³ |
| 1 Jan 2025 | 7421.4 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, Hualien City, 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/hualien-city/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.
Hualien City now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-13 05:07 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).