Air quality
Air quality in Niiza today
Updated
Moderate (US AQI 70) Acceptable for most people. Unusually sensitive people should consider shortening long or heavy exertion outdoors. Model estimate for Mon, Oct 26, 9:00 am (00:00 UTC).
Live AQI, PM2.5, PM10 and ozone for Niiza, Saitama, Japan, with a 48-hour forecast and the best time to be outside.
- US AQI now
- 70 Moderate
- PM2.5
- 9.7 µg/m³ 0.6× WHO 24-h guideline
- PM10
- 12 µg/m³
- Ozone
- 59 µg/m³
- Dominant pollutant
- PM2.5 sub-index 70
- Best hour today
- 9:00 pm AQI 60
- European AQI
- 29
Air quality in Niiza right now
Right now the modelled US Air Quality Index for Niiza, Saitama, Japan is 70, 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 70. 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 9.7 µg/m³, within the WHO 24-hour guideline of 15 µg/m³; PM10 is 12 µg/m³ against a guideline of 45; ozone is 59 µg/m³ (below the WHO 8-hour level of 100); nitrogen dioxide is 14 µg/m³ (below the 24-hour guideline of 25).
Also this hour: carbon monoxide 193 µg/m³.
Niiza AQI forecast: next 48 hours
Over the next 24 hours the AQI is forecast to range from 50 around Tue 5:00 am to 70 around Mon 9:00 am, from "Good" at best to "Moderate" at worst.
The following day looks similar, averaging about 60.
| Local time (Asia/Tokyo) | US AQI | Category | PM2.5 µg/m³ | PM10 µg/m³ | Ozone µg/m³ |
|---|---|---|---|---|---|
| Mon 9:00 am | 70 | Moderate | 9.7 | 12 | 59 |
| Mon 12:00 pm | 66 | Moderate | 12.2 | 16 | 66 |
| Mon 3:00 pm | 64 | Moderate | 13 | 16 | 55 |
| Mon 6:00 pm | 63 | Moderate | 12 | 14 | 46 |
| Mon 9:00 pm | 60 | Moderate | 8.6 | 10 | 45 |
| Tue 12:00 am | 56 | Moderate | 6 | 6 | 45 |
| Tue 3:00 am | 52 | Moderate | 4 | 4 | 45 |
| Tue 6:00 am | 50 | Good | 6.1 | 6 | 33 |
| Tue 9:00 am | 51 | Moderate | 14.5 | 15 | 38 |
| Tue 12:00 pm | 51 | Moderate | 8.3 | 9 | 94 |
| Tue 3:00 pm | 50 | Good | 10.5 | 11 | 105 |
| Tue 6:00 pm | 51 | Moderate | 30.4 | 33 | 29 |
| Tue 9:00 pm | 56 | Moderate | 47.6 | 49 | 2 |
| Wed 12:00 am | 67 | Moderate | 52.7 | 55 | 1 |
| Wed 3:00 am | 74 | Moderate | 3.6 | 5 | 67 |
| Wed 6:00 am | 74 | Moderate | 5 | 6 | 62 |
| Wed 9:00 am | 72 | Moderate | 1.6 | 2 | 77 |
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 Niiza today
Between 6 am and 9 pm local time, the cleanest air today is forecast around 9:00 pm (AQI 60, Moderate) and the worst around 9:00 am (AQI 70). That is a swing of 10 points, so a run or walk around 9:00 pm is noticeably better.
Niiza vs the rest of Japan
Across 176 Japan cities we track, the average US AQI right now is 47 (Good). Niiza at 70 is 23 points worse than average.
It ranks 147 of 176 from cleanest to most polluted; the cleanest is Gifu (16) and the most polluted Sakado (72).
For context, the median across 3,556 cities worldwide is 58.
Air quality in cities near Niiza
| City | Distance | US AQI | Category | PM2.5 µg/m³ |
|---|---|---|---|---|
| Asaka | 4 km | 62 | Moderate | 18 |
| Tokorozawa | 8 km | 62 | Moderate | 18 |
| Higashikurume | 9 km | 62 | Moderate | 18 |
| Fujimino | 9 km | 72 | Moderate | 9.4 |
| Yono | 10 km | 72 | Moderate | 9.4 |
| Nishi-Tokyo-shi | 11 km | 62 | Moderate | 18 |
| Higashimurayama | 11 km | 62 | Moderate | 18 |
| Shimotoda | 12 km | 62 | Moderate | 18 |
Model vs measured
We found no measured PM2.5 sensor cell within 25 km of Niiza, 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 70, 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 Niiza
Air quality elsewhere
Data: Open-Meteo Air Quality API, Copernicus Atmosphere Monitoring Service (CAMS).