Worst air pollution Shiojiri, today and tomorrow
Today (10 August): Air quality in Shiojiri is fair. AQI and O3 are fair; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 4:00 PM (O3: 32.5/100).
Tomorrow (11 August 2026): Air quality in Shiojiri is fair. All pollutants stay as today. Pollution peaks around 12:00 PM (O3: 36.5/100). 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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Shiojiri's air quality reflects the Nagano Prefecture Chikuma River valley position at 758 metres in the central Japanese Alps corridor, with vehicle traffic on surrounding roads and the lacquerware, wine, and manufacturing corridor contributing local sources. The surrounding Honshu Alps create topographic variation, while winter valley inversions create seasonal challenges and Shiojiri generally maintains moderate to good conditions for a Japanese inland Nagano valley city throughout most of the year.
Today - 10 August | Pollution peaks at 16:00
AQI:
Fair
32.5/100
PM2.5 (fine particles):
Good
6.5/100
PM10 (coarse particles):
Good
1.7/100
NO2 (nitrogen dioxide):
Good
7.4/100
O3 (ozone):
Fair
32.5/100
SO2 (sulfur dioxide):
Good
3.1/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
9.0/100
PM1 (ultrafine particles):
Good
9.1/100
Levels show the poorest local air quality during the day
Tomorrow - 11 August | Pollution peaks at 12:00
AQI:
Fair
36.5/100
PM2.5 (fine particles):
Good
3.8/100
PM10 (coarse particles):
Good
1.3/100
NO2 (nitrogen dioxide):
Good
4.6/100
O3 (ozone):
Fair
36.5/100
SO2 (sulfur dioxide):
Good
1.3/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
6.7/100
PM1 (ultrafine particles):
Good
3.2/100
Frequently Asked Questions
Is air quality bad in Shiojiri right now?
On 10 August 2026, overall air quality in Shiojiri is fair. AQI is the main air quality indicator at 32.5/100. Pollution peaks around 4:00 PM (O3: 32.5/100).
Will air quality be worse tomorrow in Shiojiri?
On 11 August 2026, air quality conditions in Shiojiri will be similar to today, with AQI forecast at fair at 36.5/100. Pollution peaks around 12:00 PM (O3: 36.5/100).
When is air pollution at its worst in Shiojiri?
Air quality in Shiojiri tends to be worse when road traffic and manufacturing activity build up and temperature inversions set in over the valley. The bowl-like terrain here limits how quickly pollutants can escape. This is most pronounced in winter, when inversions are more frequent.
Are air quality levels in Shiojiri 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: 9 August 2026 at 20:27 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.
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