Worst air pollution Sion, today and tomorrow
Today (16 July): Air quality in Sion is fair. AQI, NO2, and O3 are fair; PM2.5, PM10, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 12:00 PM (O3: 37.9/100).
Tomorrow (17 July 2026): Air quality in Sion is fair. NO2 decreases to good; all other pollutants stay as today. Pollution peaks around 3:00 PM (O3: 34.8/100). Airmine updates local air quality forecasts four times daily.
For long term forecasts and maps, see the Airmine app
Developed with support from the European Space Agency (ESA)’s Business Applications and Space Solutions (BASS) team
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Sion's air quality reflects its enclosed Rhône valley position beneath the Alps, with vehicle traffic on the A9 motorway contributing local sources under the valley's frequent inversions and notably dry, sunny climate.
Today - 16 July | Pollution peaks at 12:00
AQI:
Fair
37.9/100
PM2.5 (fine particles):
Good
11.1/100
PM10 (coarse particles):
Good
5.0/100
NO2 (nitrogen dioxide):
Fair
20.4/100
O3 (ozone):
Fair
37.9/100
SO2 (sulfur dioxide):
Good
0.7/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
3.5/100
PM1 (ultrafine particles):
Good
11.7/100
Levels show the poorest local air quality during the day
Tomorrow - 17 July | Pollution peaks at 15:00
AQI:
Fair
34.8/100
PM2.5 (fine particles):
Good
7.9/100
PM10 (coarse particles):
Good
7.8/100
NO2 (nitrogen dioxide):
Good
17.8/100
O3 (ozone):
Fair
34.8/100
SO2 (sulfur dioxide):
Good
0.8/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
2.2/100
PM1 (ultrafine particles):
Good
5.1/100
Pollen forecast in Sion
View pollen forecastAir quality forecasts for neighbourhoods and landmarks in Sion
Frequently Asked Questions
Is air quality bad in Sion right now?
On 16 July 2026, overall air quality in Sion is fair. AQI is the main air quality indicator at 37.9/100. Pollution peaks around 12:00 PM (O3: 37.9/100).
Will air quality be worse tomorrow in Sion?
On 17 July 2026, air quality conditions in Sion will be similar to today, with AQI forecast at fair at 34.8/100. Pollution peaks around 3:00 PM (O3: 34.8/100).
When is air pollution at its worst in Sion?
Calm winter conditions are when Sion's air quality suffers most, with vehicle traffic and orchard and vineyard machinery settling into the valley instead of clearing with the wind as usual. The rest of the year sees much better conditions in this dry valley, with summer's ozone spikes limited to the hottest, stillest afternoons.
Are air quality levels in Sion 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.
Want to see air quality forecasts for other cities in Switzerland?
Check air quality in other popular cities:
Data provided by Airmine — Last update: 16 July 2026 at 10:33 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.
For long term forecasts and maps, see the Airmine app