Air quality
Air quality in Chiayi City today
Updated
Moderate (US AQI 63) Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. Model estimate for Mon, Oct 26, 3:00 am (19:00 UTC).
Live AQI, PM2.5, PM10 and ozone for Chiayi City, Taiwan, Taiwan, with a 48-hour forecast and the best time to be outside.
- US AQI now
- 63 Moderate
- PM2.5
- 26 µg/m³ 1.7× WHO 24-h guideline
- PM10
- 28 µg/m³
- Ozone
- 5 µg/m³
- Dominant pollutant
- PM2.5 sub-index 63
- Best hour today
- 6:00 am AQI 66
- European AQI
- 55
Air quality in Chiayi City right now
Right now the modelled US Air Quality Index for Chiayi City, Taiwan, Taiwan is 63, which falls in the "Moderate" band (up to 100). Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors.
The index is driven mainly by PM2.5, whose own sub-index is 63. Fine and coarse particles come from traffic, heating, industry, dust and smoke; they build up on calm nights and clear when wind or rain arrives.
PM2.5 is 26 µg/m³, 1.7 times the WHO 24-hour guideline of 15 µg/m³; PM10 is 28 µg/m³ against a guideline of 45; ozone is 5 µg/m³ (below the WHO 8-hour level of 100); nitrogen dioxide is 51 µg/m³ (above the 24-hour guideline of 25).
Also this hour: carbon monoxide 559 µg/m³.
NASA FIRMS shows 2 fire hotspots within 300 km in the last day (nearest about 238 km), but particle levels are not elevated enough to point to smoke right now.
Chiayi City AQI forecast: next 48 hours
Over the next 24 hours the AQI is forecast to range from 63 around Mon 3:00 am to 85 around Tue 1:00 am, staying "Moderate" throughout.
The following day is expected to be worse, averaging about 90 against 74 for the next 24 hours.
| Local time (Asia/Taipei) | US AQI | Category | PM2.5 µg/m³ | PM10 µg/m³ | Ozone µg/m³ |
|---|---|---|---|---|---|
| Mon 3:00 am | 63 | Moderate | 25.8 | 28 | 5 |
| Mon 6:00 am | 66 | Moderate | 23.2 | 24 | 14 |
| Mon 9:00 am | 68 | Moderate | 16.5 | 17 | 63 |
| Mon 12:00 pm | 70 | Moderate | 25.1 | 27 | 125 |
| Mon 3:00 pm | 73 | Moderate | 32 | 36 | 134 |
| Mon 6:00 pm | 77 | Moderate | 33.9 | 41 | 91 |
| Mon 9:00 pm | 81 | Moderate | 31.4 | 37 | 47 |
| Tue 12:00 am | 84 | Moderate | 30.9 | 36 | 34 |
| Tue 3:00 am | 85 | Moderate | 28.2 | 31 | 35 |
| Tue 6:00 am | 86 | Moderate | 27.4 | 31 | 43 |
| Tue 9:00 am | 87 | Moderate | 28.1 | 34 | 61 |
| Tue 12:00 pm | 90 | Moderate | 33.4 | 41 | 99 |
| Tue 3:00 pm | 91 | Moderate | 35.9 | 44 | 118 |
| Tue 6:00 pm | 92 | Moderate | 33.1 | 41 | 75 |
| Tue 9:00 pm | 92 | Moderate | 33.8 | 42 | 29 |
| Wed 12:00 am | 92 | Moderate | 29.7 | 35 | 22 |
| Wed 3:00 am | 92 | Moderate | 24.4 | 29 | 23 |
Every third hour of the CAMS forecast via Open-Meteo. US AQI uses rolling averages (24 h for particles, 8 h for ozone), so it moves more slowly than the hourly concentrations.
Best time to be outside in Chiayi City today
Between 6 am and 9 pm local time, the cleanest air today is forecast around 6:00 am (AQI 66, Moderate) and the worst around 9:00 pm (AQI 81). That is a swing of 15 points, so a run or walk around 6:00 am is noticeably better.
Chiayi City vs the rest of Taiwan
Across 18 Taiwan cities we track, the average US AQI right now is 68 (Moderate). Chiayi City at 63 is 5 points cleaner than average.
For context, the median across 2,646 cities worldwide is 63.
Air quality in cities near Chiayi City
| City | Distance | US AQI | Category | PM2.5 µg/m³ |
|---|---|---|---|---|
| Yongkang | 54 km | 97 | Moderate | 50.6 |
| Tainan | 60 km | 97 | Moderate | 50.6 |
| Taichung | 78 km | 80 | Moderate | 28.5 |
| Fengshan | 95 km | 97 | Moderate | 50.6 |
| Kaohsiung | 97 km | 97 | Moderate | 50.6 |
| Toufen | 142 km | 57 | Moderate | 15.6 |
| Hsinchu | 156 km | 57 | Moderate | 15.6 |
| Zhubei | 161 km | 57 | Moderate | 15.6 |
Model vs measured
We found no measured PM2.5 sensor cell within 25 km of Chiayi City, so the numbers on this page are model estimates. Models capture regional pollution well but can miss very local sources such as a busy road or a nearby fire.
Advice for sensitive groups
At 63, most people are fine outdoors. If you are unusually sensitive to PM2.5, keep long or intense workouts to the cleaner hours shown above.
What the US AQI numbers mean
| US AQI | Category | What it means |
|---|---|---|
| 0-50 | Good | Air quality is satisfactory and poses little or no risk; a good time for outdoor activity. |
| 51-100 | Moderate | Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. |
| 101-150 | Unhealthy for Sensitive Groups | People with heart or lung disease, older adults, children and teens should cut back on prolonged or heavy exertion outdoors. |
| 151-200 | Unhealthy | Everyone should reduce prolonged or heavy exertion outdoors; sensitive groups should avoid it and keep windows closed. |
| 201-300 | Very Unhealthy | Health alert: everyone should avoid prolonged or heavy exertion outdoors, and sensitive groups should stay indoors. |
| 301-500 | Hazardous | Emergency conditions: everyone should avoid all outdoor physical activity and stay indoors with filtered air if possible. The scale tops out at 500; heavier dust or smoke is shown as 500. |
Values on this page are modelled by CAMS (Copernicus) and served by Open-Meteo; they are estimates for the area around the city centre, not readings from an official monitor.
Nearby cities
More for Chiayi City
Air quality elsewhere
Data: Open-Meteo Air Quality API, Copernicus Atmosphere Monitoring Service (CAMS), NASA FIRMS.