SmogRank / Taiwan / Taiwan

Air quality in Chiayi City

Taiwan, Taiwan. PM2.5 from 1 reference monitor, updated hourly.

13.0 µg/m³
Moderate

Latest hour (05:00 UTC), 0.9× the WHO 24-hour guideline.

Rank

24 h
–
not enough data
7 days
#278
of 2,330 · 14.0 µg/m³
30 days
#294
of 2,327 · 12.5 µg/m³
Year
#308
of 2,160 · 15.4 µg/m³

Why it ranks here

Seasonal. Over the past year its worst months were January, February, March, December, averaging up to 25.8 µg/m³ against 7.4 in its cleanest month. Seasonal peaks usually come from heating, crop burning, fire or dust seasons.

Based on Chiayi City's own measurements; causes are the usual kinds for a pattern like this, not a confirmed source.

Last 4 days, hour by hour

15302026-10-01 03:00 UTC: 10.0 µg/m³2026-10-01 04:00 UTC: 15.0 µg/m³2026-10-01 05:00 UTC: 13.0 µg/m³Sep 28Sep 29Sep 30Oct 1

Times in UTC. Dashed line: WHO 24-hour guideline (15 µg/m³).

Every day for a year

SepNovDecJanFebMarAprMayJunJulAugSepMonWedFri2025-09-29: 10.6 µg/m³2025-09-30: 14.0 µg/m³2025-10-01: 16.5 µg/m³2025-10-02: 10.2 µg/m³2025-10-03: 17.5 µg/m³2025-10-04: 17.5 µg/m³2025-10-05: 15.3 µg/m³2025-10-06: 17.5 µg/m³2025-10-07: 17.6 µg/m³2025-10-08: 14.9 µg/m³2025-10-09: 14.3 µg/m³2025-10-10: 14.6 µg/m³2025-10-11: no data2025-10-12: no data2025-10-13: no data2025-10-14: no data2025-10-15: no data2025-10-16: no data2025-10-17: no data2025-10-18: no data2025-10-19: no data2025-10-20: no data2025-10-21: no data2025-10-22: no data2025-10-23: no data2025-10-24: no data2025-10-25: no data2025-10-26: no data2025-10-27: no data2025-10-28: no data2025-10-29: no data2025-10-30: no data2025-10-31: no data2025-11-01: no data2025-11-02: no data2025-11-03: no data2025-11-04: no data2025-11-05: no data2025-11-06: no data2025-11-07: no data2025-11-08: no data2025-11-09: no data2025-11-10: no data2025-11-11: no data2025-11-12: no data2025-11-13: no data2025-11-14: no data2025-11-15: no data2025-11-16: no data2025-11-17: no data2025-11-18: no data2025-11-19: 14.3 µg/m³2025-11-20: 19.0 µg/m³2025-11-21: 19.1 µg/m³2025-11-22: 23.8 µg/m³2025-11-23: 23.2 µg/m³2025-11-24: 26.3 µg/m³2025-11-25: 25.3 µg/m³2025-11-26: 31.6 µg/m³2025-11-27: 17.2 µg/m³2025-11-28: 27.5 µg/m³2025-11-29: 31.0 µg/m³2025-11-30: 29.3 µg/m³2025-12-01: 22.8 µg/m³2025-12-02: 21.7 µg/m³2025-12-03: 21.2 µg/m³2025-12-04: 19.1 µg/m³2025-12-05: 19.5 µg/m³2025-12-06: 18.4 µg/m³2025-12-07: 24.6 µg/m³2025-12-08: 20.0 µg/m³2025-12-09: 18.6 µg/m³2025-12-10: 22.2 µg/m³2025-12-11: 18.2 µg/m³2025-12-12: 26.4 µg/m³2025-12-13: 22.1 µg/m³2025-12-14: 16.9 µg/m³2025-12-15: 20.6 µg/m³2025-12-16: 25.2 µg/m³2025-12-17: 26.5 µg/m³2025-12-18: 24.0 µg/m³2025-12-19: 34.8 µg/m³2025-12-20: 37.9 µg/m³2025-12-21: 32.7 µg/m³2025-12-22: 17.2 µg/m³2025-12-23: 27.8 µg/m³2025-12-24: 31.8 µg/m³2025-12-25: 17.0 µg/m³2025-12-26: 16.1 µg/m³2025-12-27: 18.1 µg/m³2025-12-28: 18.3 µg/m³2025-12-29: 17.0 µg/m³2025-12-30: 18.6 µg/m³2025-12-31: 16.0 µg/m³2026-01-01: 10.0 µg/m³2026-01-02: 10.0 µg/m³2026-01-03: 18.2 µg/m³2026-01-04: 17.5 µg/m³2026-01-05: 26.0 µg/m³2026-01-06: 21.3 µg/m³2026-01-07: 24.3 µg/m³2026-01-08: 26.8 µg/m³2026-01-09: 23.5 µg/m³2026-01-10: 22.5 µg/m³2026-01-11: 22.5 µg/m³2026-01-12: 25.1 µg/m³2026-01-13: 27.2 µg/m³2026-01-14: 31.8 µg/m³2026-01-15: 34.6 µg/m³2026-01-16: 26.1 µg/m³2026-01-17: 33.9 µg/m³2026-01-18: 26.0 µg/m³2026-01-19: 28.7 µg/m³2026-01-20: 16.0 µg/m³2026-01-21: 8.5 µg/m³2026-01-22: 8.7 µg/m³2026-01-23: 11.7 µg/m³2026-01-24: 17.9 µg/m³2026-01-25: 20.9 µg/m³2026-01-26: 35.6 µg/m³2026-01-27: 33.5 µg/m³2026-01-28: 15.8 µg/m³2026-01-29: 20.6 µg/m³2026-01-30: 27.5 µg/m³2026-01-31: 25.1 µg/m³2026-02-01: 9.7 µg/m³2026-02-02: 19.3 µg/m³2026-02-03: 27.0 µg/m³2026-02-04: 35.3 µg/m³2026-02-05: 36.8 µg/m³2026-02-06: 33.0 µg/m³2026-02-07: 17.3 µg/m³2026-02-08: 20.2 µg/m³2026-02-09: 22.2 µg/m³2026-02-10: 26.4 µg/m³2026-02-11: 25.7 µg/m³2026-02-12: 28.6 µg/m³2026-02-13: 37.5 µg/m³2026-02-14: 29.3 µg/m³2026-02-15: 19.4 µg/m³2026-02-16: 35.8 µg/m³2026-02-17: 18.6 µg/m³2026-02-18: 15.9 µg/m³2026-02-19: 24.2 µg/m³2026-02-20: 28.5 µg/m³2026-02-21: 31.0 µg/m³2026-02-22: 25.5 µg/m³2026-02-23: 35.5 µg/m³2026-02-24: 32.0 µg/m³2026-02-25: 25.3 µg/m³2026-02-26: 21.6 µg/m³2026-02-27: 17.3 µg/m³2026-02-28: 22.3 µg/m³2026-03-01: 17.4 µg/m³2026-03-02: 16.4 µg/m³2026-03-03: 16.7 µg/m³2026-03-04: 13.7 µg/m³2026-03-05: 25.7 µg/m³2026-03-06: 17.6 µg/m³2026-03-07: 18.2 µg/m³2026-03-08: 21.9 µg/m³2026-03-09: 18.0 µg/m³2026-03-10: 14.5 µg/m³2026-03-11: 19.9 µg/m³2026-03-12: 15.8 µg/m³2026-03-13: 22.0 µg/m³2026-03-14: 25.2 µg/m³2026-03-15: 23.1 µg/m³2026-03-16: 22.8 µg/m³2026-03-17: 27.4 µg/m³2026-03-18: 16.7 µg/m³2026-03-19: 19.1 µg/m³2026-03-20: 31.6 µg/m³2026-03-21: 25.7 µg/m³2026-03-22: 28.5 µg/m³2026-03-23: 34.0 µg/m³2026-03-24: 35.3 µg/m³2026-03-25: 27.5 µg/m³2026-03-26: 26.9 µg/m³2026-03-27: 20.3 µg/m³2026-03-28: 29.4 µg/m³2026-03-29: 29.2 µg/m³2026-03-30: 25.8 µg/m³2026-03-31: 14.6 µg/m³2026-04-01: 23.6 µg/m³2026-04-02: 26.2 µg/m³2026-04-03: 20.3 µg/m³2026-04-04: 16.9 µg/m³2026-04-05: 15.1 µg/m³2026-04-06: 12.9 µg/m³2026-04-07: 11.0 µg/m³2026-04-08: 18.0 µg/m³2026-04-09: 25.7 µg/m³2026-04-10: 14.5 µg/m³2026-04-11: 16.0 µg/m³2026-04-12: 19.2 µg/m³2026-04-13: 16.5 µg/m³2026-04-14: 10.8 µg/m³2026-04-15: 10.7 µg/m³2026-04-16: 20.3 µg/m³2026-04-17: 28.0 µg/m³2026-04-18: 29.8 µg/m³2026-04-19: 24.2 µg/m³2026-04-20: 23.4 µg/m³2026-04-21: 21.9 µg/m³2026-04-22: 17.5 µg/m³2026-04-23: 19.4 µg/m³2026-04-24: 20.4 µg/m³2026-04-25: 19.4 µg/m³2026-04-26: 19.1 µg/m³2026-04-27: 16.8 µg/m³2026-04-28: 17.1 µg/m³2026-04-29: 11.7 µg/m³2026-04-30: 14.0 µg/m³2026-05-01: 18.9 µg/m³2026-05-02: 19.9 µg/m³2026-05-03: 11.6 µg/m³2026-05-04: 20.1 µg/m³2026-05-05: 26.4 µg/m³2026-05-06: 5.8 µg/m³2026-05-07: 12.8 µg/m³2026-05-08: 15.0 µg/m³2026-05-09: 12.9 µg/m³2026-05-10: 12.1 µg/m³2026-05-11: 14.8 µg/m³2026-05-12: 15.8 µg/m³2026-05-13: 15.3 µg/m³2026-05-14: 14.8 µg/m³2026-05-15: 8.3 µg/m³2026-05-16: 8.1 µg/m³2026-05-17: 6.0 µg/m³2026-05-18: 8.4 µg/m³2026-05-19: 8.6 µg/m³2026-05-20: 8.5 µg/m³2026-05-21: no data2026-05-22: no data2026-05-23: no data2026-05-24: no data2026-05-25: no data2026-05-26: 9.1 µg/m³2026-05-27: 9.2 µg/m³2026-05-28: 9.4 µg/m³2026-05-29: 15.5 µg/m³2026-05-30: 18.3 µg/m³2026-05-31: 20.1 µg/m³2026-06-01: 22.7 µg/m³2026-06-02: 19.3 µg/m³2026-06-03: 12.8 µg/m³2026-06-04: 1.5 µg/m³2026-06-05: 4.8 µg/m³2026-06-06: 14.1 µg/m³2026-06-07: 7.9 µg/m³2026-06-08: 2.1 µg/m³2026-06-09: 1.9 µg/m³2026-06-10: 7.9 µg/m³2026-06-11: 11.8 µg/m³2026-06-12: 12.1 µg/m³2026-06-13: no data2026-06-14: 4.5 µg/m³2026-06-15: 1.8 µg/m³2026-06-16: 2.1 µg/m³2026-06-17: 4.8 µg/m³2026-06-18: 7.1 µg/m³2026-06-19: 11.2 µg/m³2026-06-20: 12.8 µg/m³2026-06-21: 8.1 µg/m³2026-06-22: 6.2 µg/m³2026-06-23: 6.2 µg/m³2026-06-24: 8.4 µg/m³2026-06-25: 5.9 µg/m³2026-06-26: 2.8 µg/m³2026-06-27: 4.3 µg/m³2026-06-28: 5.0 µg/m³2026-06-29: 9.0 µg/m³2026-06-30: 7.8 µg/m³2026-07-01: 8.9 µg/m³2026-07-02: 11.0 µg/m³2026-07-03: 6.4 µg/m³2026-07-04: 3.6 µg/m³2026-07-05: 3.0 µg/m³2026-07-06: 3.8 µg/m³2026-07-07: 4.2 µg/m³2026-07-08: 4.6 µg/m³2026-07-09: 9.4 µg/m³2026-07-10: 12.3 µg/m³2026-07-11: 5.3 µg/m³2026-07-12: 5.8 µg/m³2026-07-13: 3.1 µg/m³2026-07-14: 4.4 µg/m³2026-07-15: 5.6 µg/m³2026-07-16: 5.9 µg/m³2026-07-17: 5.0 µg/m³2026-07-18: 5.5 µg/m³2026-07-19: 5.5 µg/m³2026-07-20: 8.0 µg/m³2026-07-21: 9.6 µg/m³2026-07-22: 12.3 µg/m³2026-07-23: 13.9 µg/m³2026-07-24: 17.7 µg/m³2026-07-25: 13.0 µg/m³2026-07-26: 6.6 µg/m³2026-07-27: 5.3 µg/m³2026-07-28: 6.6 µg/m³2026-07-29: 7.1 µg/m³2026-07-30: 8.4 µg/m³2026-07-31: 6.7 µg/m³2026-08-01: 7.3 µg/m³2026-08-02: 5.9 µg/m³2026-08-03: 9.2 µg/m³2026-08-04: 12.6 µg/m³2026-08-05: 9.7 µg/m³2026-08-06: 11.7 µg/m³2026-08-07: 17.6 µg/m³2026-08-08: 15.3 µg/m³2026-08-09: 14.1 µg/m³2026-08-10: 12.5 µg/m³2026-08-11: 17.4 µg/m³2026-08-12: 18.0 µg/m³2026-08-13: 15.2 µg/m³2026-08-14: 9.6 µg/m³2026-08-15: 5.3 µg/m³2026-08-16: 4.5 µg/m³2026-08-17: 10.1 µg/m³2026-08-18: 12.3 µg/m³2026-08-19: 7.9 µg/m³2026-08-20: 2.9 µg/m³2026-08-21: 2.3 µg/m³2026-08-22: 2.0 µg/m³2026-08-23: 1.6 µg/m³2026-08-24: 1.9 µg/m³2026-08-25: 0.4 µg/m³2026-08-26: 6.4 µg/m³2026-08-27: 6.0 µg/m³2026-08-28: 5.3 µg/m³2026-08-29: 2.7 µg/m³2026-08-30: 1.0 µg/m³2026-08-31: 0.9 µg/m³2026-09-01: 1.1 µg/m³2026-09-02: 3.3 µg/m³2026-09-03: 1.1 µg/m³2026-09-04: 3.3 µg/m³2026-09-05: 5.0 µg/m³2026-09-06: 6.3 µg/m³2026-09-07: 12.5 µg/m³2026-09-08: 13.4 µg/m³2026-09-09: 15.0 µg/m³2026-09-10: 16.3 µg/m³2026-09-11: 18.2 µg/m³2026-09-12: 16.0 µg/m³2026-09-13: 10.3 µg/m³2026-09-14: 8.8 µg/m³2026-09-15: 12.2 µg/m³2026-09-16: 15.7 µg/m³2026-09-17: 13.4 µg/m³2026-09-18: 19.6 µg/m³2026-09-19: 18.4 µg/m³2026-09-20: 19.6 µg/m³2026-09-21: 16.2 µg/m³2026-09-22: 12.8 µg/m³2026-09-23: 17.3 µg/m³2026-09-24: 24.1 µg/m³2026-09-25: 23.4 µg/m³2026-09-26: 14.9 µg/m³2026-09-27: 11.0 µg/m³2026-09-28: 7.3 µg/m³2026-09-29: 7.4 µg/m³2026-09-30: 10.2 µg/m³
Good 0–9.0Moderate 9.1+Unhealthy for sensitive groups 35.5+Unhealthy 55.5+Very unhealthy 125.5+Hazardous 225.5+No data

180 of 320 measured days were over the WHO 24-hour guideline.

Daily world rank

#1#2387OctNovDecJanFebMarAprMayJunJulAugSep

Rank on each day's board (1 = most polluted city that day).

2026 against 2025, month by month

15Jan 2025: 25.2 µg/m³Jan 2026: 22.5 µg/m³JanFeb 2025: 24.8 µg/m³Feb 2026: 25.8 µg/m³FebMar 2025: 20.6 µg/m³Mar 2026: 22.6 µg/m³MarApr 2025: 19.1 µg/m³Apr 2026: 18.7 µg/m³AprMay 2025: 10.6 µg/m³May 2026: 13.3 µg/m³MayJun 2025: 5.5 µg/m³Jun 2026: 7.8 µg/m³JunJul 2026: 7.4 µg/m³JulAug 2026: 8.1 µg/m³AugSep 2025: 8.8 µg/m³Sep 2026: 12.5 µg/m³SepOct 2025: 15.6 µg/m³OctNov 2025: 24.0 µg/m³NovDec 2025: 22.3 µg/m³Dec

Faded bars: 2025. A month shows once it has 10 measured days.

This week against past years

This weekThis week: 14.0 µg/m³14.020252025: 11.6 µg/m³11.6

Mean PM2.5 for 24 Sept to 30 Sept in each year. Dashed line: WHO 24-hour guideline.

Monitors

StationOperatorType
嘉義市 - 嘉義OGDL-Taiwan 1.0TaiwanReference

The city's value is the median of its reference monitors each hour; low-cost sensors are listed but not counted when reference monitors exist. Data via OpenAQ; licences as listed. How we rank. Embed this on your site.

Other cities in Taiwan

Jincheng 15.0Zhushan 14.7Erlin 14.6Yuanlin 14.5Douliu 14.4Beigang 14.2Erlun 13.5Nantou 13.4Tainan 13.3Fengshan 13.3Taichung 13.1Puli 13.1

30-day averages, µg/m³. All of Taiwan →

Updated 2026-10-01 06:07 UTC. Values are PM2.5 in µg/m³ (fine particles), the median of each city's monitors.