Worst air pollution Hanyū, today and tomorrow
Today (21 September): Air quality in Hanyū is fair. AQI and NO2 are fair; PM2.5, PM10, O3, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 12:00 PM (NO2: 25.2/100).
Tomorrow (22 September 2026): Air quality in Hanyū is moderate. AQI worsens to moderate; PM2.5 increases to moderate; PM10 increases to fair; NO2 increases to moderate; O3 increases to fair; SO2 increases to fair; PM1 increases to moderate; all other pollutants stay as today. Pollution peaks around 6:00 PM (NO2: 50.1/100). Airmine updates local air quality forecasts four times daily.
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Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Hanyū's air quality reflects the flat Saitama northern Arakawa River plain position, with vehicle traffic on surrounding roads and the manufacturing, agricultural, and residential character contributing local sources. The flat Kanto Plain allows reasonable dispersal, while summer photochemical ozone from the broader Kanto corridor and the Karakkaze Foehn winds create local meteorological dynamics and Hanyū generally maintains moderate Japanese inland Kanto plain suburban readings throughout most of the year.
Today - 21 September | Pollution peaks at 12:00
AQI:
Fair
25.2/100
PM2.5 (fine particles):
Good
14.8/100
PM10 (coarse particles):
Good
11.0/100
NO2 (nitrogen dioxide):
Fair
25.2/100
O3 (ozone):
Good
13.0/100
SO2 (sulfur dioxide):
Good
4.5/100
CO (carbon monoxide):
Good
0.7/100
HCHO (formaldehyde):
Good
6.5/100
PM1 (ultrafine particles):
Good
15.7/100
Levels show the poorest local air quality during the day
Tomorrow - 22 September | Pollution peaks at 18:00
AQI:
Moderate
50.1/100
PM2.5 (fine particles):
Moderate
41.0/100
PM10 (coarse particles):
Fair
30.3/100
NO2 (nitrogen dioxide):
Moderate
50.1/100
O3 (ozone):
Fair
23.8/100
SO2 (sulfur dioxide):
Fair
25.5/100
CO (carbon monoxide):
Good
1.3/100
HCHO (formaldehyde):
Good
7.9/100
PM1 (ultrafine particles):
Moderate
42.5/100
Frequently Asked Questions
Is air quality bad in Hanyū right now?
On 21 September 2026, overall air quality in Hanyū is fair. AQI is the main air quality indicator at 25.2/100. Pollution peaks around 12:00 PM (NO2: 25.2/100).
Will air quality be worse tomorrow in Hanyū?
On 22 September 2026, air quality conditions in Hanyū will be worse than today, with AQI forecast at moderate at 50.1/100. Pollution peaks around 6:00 PM (NO2: 50.1/100).
When is air pollution at its worst in Hanyū?
The biggest local contributors to pollution in Hanyū are road traffic, steel, cement, and chemical production, together with textile and manufacturing operations, particularly once summer heat and strong sunlight build up. Heat and sunlight combine with emissions to form ozone at ground level. Readings are generally lower during the cooler, cloudier months.
Are air quality levels in Hanyū based on measurements or forecasts?
It is forecasts derived by downscaling forecasts provided by EU’s Copernicus Atmosphere Monitoring Service (CAMS) by taking into account local conditions such as traffic patterns. CAMS bases its forecast on satellite measurements of particles and chemical compounds in the atmosphere. Airmine’s services were developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team.
Why doesn’t the forecast always reflect wildfire impacts?
Airmine’s forecast uses CAMS (Copernicus Atmosphere Monitoring Service) as its background atmospheric model. While CAMS includes wildfire emissions, these are derived from satellite observations and are not available in real time. During rapidly evolving wildfire events, there may therefore be a delay before increased emissions are incorporated into the model. As a result, the forecast may temporarily underestimate PM₂.₅ and other pollutants associated with wildfire smoke.
During rapidly evolving wildfire events, CAMS may lag by approximately 1–2 days before increased wildfire emissions are fully represented, which can lead to temporary underestimation of PM₂.₅ concentrations in Airmine’s forecast.
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Data provided by Airmine — Last update: 22 September 2026 at 02:59 CEST (Data is updated four times daily.)
This forecast is produced independently using Airmine's own atmospheric data and models.
Unless explicitly made clear, the content on this site has not been paid for by external organisations and is Airmine's sole responsibility.
Disclaimer: Forecasts are provided for informational purposes only and should not be relied upon as medical advice. Actual pollen and air quality conditions may vary from the forecast. If you have allergies, asthma, or another medical condition, consult a healthcare professional. Please see our Terms of Service for important information about limitations of liability.
Some text on this page may be generated or summarised using artificial intelligence (AI). Wherever possible, AI-generated content is enriched with Airmine's proprietary data to improve its accuracy and relevance. However, AI-generated content may still contain errors, omissions, or inaccuracies.
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