SmogRank / Taiwan / Taiwan / Changhua
Changhua, month by month
Changhua has a measured daily mean on 840 days since 8 February 2024. Its worst month was February 2026, at 71 US AQI (19.6 µg/m³), 570th of 2,866 cities on that month's world ranking. Its cleanest was July 2024, at 27 US AQI (4.8 µg/m³). 2025 averaged 61 US AQI (14.7 µg/m³), against 56 US AQI (12.0 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.
Changhua's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| February 2026 | 7119.6 µg/m³ | 570thof 2,866 | – |
| April 2025 | 7019.5 µg/m³ | 368thof 2,951 | – |
| March 2024 | 6818.2 µg/m³ | 185thof 1,698 | – |
| March 2026 | 6818.1 µg/m³ | 670thof 2,971 | – |
| January 2025 | 6717.6 µg/m³ | 381stof 2,474 | Taiwan, 21 to 22 January 2025 |
| April 2024 | 6516.7 µg/m³ | 333rdof 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.
Changhua's worst days
| Day | US AQI | Episode |
|---|---|---|
| 22 Jan 2025 | 13047.1 µg/m³ | Taiwan, 21 to 22 January 2025 |
| 11 Mar 2025 | 10838.4 µg/m³ | Taiwan, March 2025 |
| 27 Feb 2025 | 9834.2 µg/m³ | – |
| 14 Nov 2024 | 9733.7 µg/m³ | Taiwan, November 2024 |
| 16 Mar 2024 | 9633.2 µg/m³ | – |
| 15 Nov 2024 | 9633.2 µg/m³ | Taiwan, November 2024 |
| 21 Feb 2026 | 9432.4 µg/m³ | – |
| 21 Jan 2025 | 9231.2 µg/m³ | Taiwan, 21 to 22 January 2025 |
| 6 Feb 2025 | 9130.8 µg/m³ | – |
| 23 Feb 2026 | 9030.0 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, Changhua, 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/changhua/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.
Changhua 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).