Worst air pollution Nagano, today and tomorrow
Today (21 September): Air quality in Nagano is fair. AQI and NO2 are fair; PM2.5, PM10, O3, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 6:00 PM (NO2: 24.8/100).
Tomorrow (22 September 2026): Air quality in Nagano is fair. PM2.5 increases to fair; O3 increases to fair; all other pollutants stay as today. Pollution peaks around 11:00 PM (PM2.5: 32.7/100). 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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Nagano's air quality benefits from its elevated Nagano Basin position at 371 metres surrounded by the Japanese Alps, with vehicle traffic on surrounding roads and the precision manufacturing, Winter Olympics legacy, and tourism corridor contributing local sources. The surrounding Northern Alps create dramatic topographic variation and winter inversions in the enclosed mountain basin create seasonal challenges, while summer conditions are generally excellent with clean Alpine westerly airflows providing outstanding conditions throughout the warmer months.
Today - 21 September | Pollution peaks at 18:00
AQI:
Fair
24.8/100
PM2.5 (fine particles):
Good
12.2/100
PM10 (coarse particles):
Good
4.3/100
NO2 (nitrogen dioxide):
Fair
24.8/100
O3 (ozone):
Good
14.2/100
SO2 (sulfur dioxide):
Good
2.1/100
CO (carbon monoxide):
Good
0.6/100
HCHO (formaldehyde):
Good
5.4/100
PM1 (ultrafine particles):
Good
3.2/100
Levels show the poorest local air quality during the day
Tomorrow - 22 September | Pollution peaks at 23:00
AQI:
Fair
32.7/100
PM2.5 (fine particles):
Fair
32.7/100
PM10 (coarse particles):
Good
15.3/100
NO2 (nitrogen dioxide):
Fair
27.8/100
O3 (ozone):
Fair
25.0/100
SO2 (sulfur dioxide):
Good
1.3/100
CO (carbon monoxide):
Good
0.8/100
HCHO (formaldehyde):
Good
4.4/100
PM1 (ultrafine particles):
Good
6.8/100
Frequently Asked Questions
Is air quality bad in Nagano right now?
On 21 September 2026, overall air quality in Nagano is fair. AQI is the main air quality indicator at 24.8/100. Pollution peaks around 6:00 PM (NO2: 24.8/100).
Will air quality be worse tomorrow in Nagano?
On 22 September 2026, air quality conditions in Nagano will be similar to today, with AQI forecast at fair at 32.7/100. Pollution peaks around 11:00 PM (PM2.5: 32.7/100).
When is air pollution at its worst in Nagano?
Pollution in Nagano typically rises when road traffic, manufacturing and food processing, as well as seasonal tourism traffic combine, especially once 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 Nagano 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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