Air quality · Japan
Chiba Air Quality Index (AQI) today
Modelled estimate for 21:00 local time (UTC+9), refreshed 3 Nov, 07:52 UTC+0.
Live estimate · modelled
US EPA AQI21:00 UTC+9, 3 Nov Main pollutant: PM2.5
Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.
This page uses EPA’s NowCast, which follows the last few hours, as the US government’s AirNow does. On a 24-hour average of particles, as many apps show, it is 77.
Over the next 24 hours the model expects the AQI to range from 47 around 02:00 to 78 around 17:00 (4 Nov).
590th most polluted of 849 cities worldwide right now, 15th of 19 in Japan.
What to do today
- Long walk or run outside OK, lighter if very sensitive
- Kids playing outside OK
- Airing the house Open
- Mask outdoors Not needed
Based on the US EPA’s health statement: “Air quality is acceptable. However, there may be a risk for some people, particularly those who are unusually sensitive to air pollution.” General guidance, not medical advice.
Last 24 hours and next 48
Past hours Forecast
US EPA AQI per hour, UTC+9. Particles use EPA’s NowCast (a 12-hour weighted average), ozone and CO an 8-hour average. Lighter bars are the CAMS forecast.
Show as a table
| Time | AQI |
|---|---|
| Mon 22:00 | 91 |
| Mon 23:00 | 93 |
| Tue 00:00 | 98 |
| Tue 01:00 | 106 |
| Tue 02:00 | 113 |
| Tue 03:00 | 115 |
| Tue 04:00 | 112 |
| Tue 05:00 | 108 |
| Tue 06:00 | 108 |
| Tue 07:00 | 112 |
| Tue 08:00 | 111 |
| Tue 09:00 | 95 |
| Tue 10:00 | 73 |
| Tue 11:00 | 60 |
| Tue 12:00 | 52 |
| Tue 13:00 | 41 |
| Tue 14:00 | 36 |
| Tue 15:00 | 34 |
| Tue 16:00 | 38 |
| Tue 17:00 | 53 |
| Tue 18:00 | 57 |
| Tue 19:00 | 58 |
| Tue 20:00 | 57 |
| Tue 21:00 · Now | 54 |
| Tue 22:00 · Forecast | 52 |
| Tue 23:00 · Forecast | 51 |
| Wed 00:00 · Forecast | 49 |
| Wed 01:00 · Forecast | 48 |
| Wed 02:00 · Forecast | 47 |
| Wed 03:00 · Forecast | 48 |
| Wed 04:00 · Forecast | 52 |
| Wed 05:00 · Forecast | 52 |
| Wed 06:00 · Forecast | 54 |
| Wed 07:00 · Forecast | 57 |
| Wed 08:00 · Forecast | 65 |
| Wed 09:00 · Forecast | 69 |
| Wed 10:00 · Forecast | 71 |
| Wed 11:00 · Forecast | 72 |
| Wed 12:00 · Forecast | 71 |
| Wed 13:00 · Forecast | 71 |
| Wed 14:00 · Forecast | 72 |
| Wed 15:00 · Forecast | 73 |
| Wed 16:00 · Forecast | 76 |
| Wed 17:00 · Forecast | 78 |
| Wed 18:00 · Forecast | 78 |
| Wed 19:00 · Forecast | 77 |
| Wed 20:00 · Forecast | 76 |
| Wed 21:00 · Forecast | 75 |
| Wed 22:00 · Forecast | 74 |
| Wed 23:00 · Forecast | 74 |
| Thu 00:00 · Forecast | 71 |
| Thu 01:00 · Forecast | 64 |
| Thu 02:00 · Forecast | 59 |
| Thu 03:00 · Forecast | 55 |
| Thu 04:00 · Forecast | 53 |
| Thu 05:00 · Forecast | 52 |
| Thu 06:00 · Forecast | 52 |
| Thu 07:00 · Forecast | 54 |
| Thu 08:00 · Forecast | 56 |
| Thu 09:00 · Forecast | 57 |
| Thu 10:00 · Forecast | 56 |
| Thu 11:00 · Forecast | 57 |
| Thu 12:00 · Forecast | 55 |
| Thu 13:00 · Forecast | 53 |
| Thu 14:00 · Forecast | 52 |
| Thu 15:00 · Forecast | 52 |
| Thu 16:00 · Forecast | 55 |
Pollutants this hour
- PM2.5 9.2 µg/m³ 24-hour mean 23.3 µg/m³ · 1.6× WHO’s 24-hour guideline (15) 54
- PM10 11 µg/m³ 11
- O₃ 55 µg/m³ 23
- NO₂ 20 µg/m³ 9
- SO₂ 8 µg/m³ 4
- CO 0.15 mg/m³ 2
Modelled concentrations at the city’s location (CAMS). The sub-index uses the same averaging as the headline, so the highest one is the AQI.
Nearby cities
Where this number comes from
The Copernicus Atmosphere Monitoring Service (CAMS) forecasts air pollution worldwide on a grid (about 11 km over Europe, about 45 km elsewhere). We take the grid value at Chiba’s coordinates and score it with the US EPA’s method. It is a model, not a measurement: a nearby monitoring station can read quite differently, especially next to busy roads or during fires and dust storms.
Full methodology · Data: CAMS via Open-Meteo (CC BY 4.0); city list: GeoNames (CC BY 4.0).
- Good 0–50
- Moderate 51–100
- Unhealthy for sensitive groups 101–150
- Unhealthy 151–200
- Very unhealthy 201–300
- Hazardous 301–500