Worst air pollution Siena, today and tomorrow
Today (16 July): Air quality in Siena is fair. NO2 is fair; AQI and O3 are medium; PM2.5, PM10, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 4:00 PM (O3: 51.8/100).
Tomorrow (17 July 2026): Air quality in Siena is fair. HCHO increases to fair; all other pollutants stay as today. Pollution peaks around 11:00 AM (O3: 43.8/100). 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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Siena's air quality benefits from its elevated Tuscan hill position at 322 metres, with consistent Tuscan hillside breezes providing reliable ventilation across this UNESCO heritage medieval city. Vehicle traffic on the SR2 Cassia and tourism operations are the primary local sources, while the surrounding Crete Senesi and Chianti hills create topographic variation and Siena's medieval core with significant car restrictions and the elevated hilltop position generally maintain moderate to good conditions throughout most of the year.
Today - 16 July | Pollution peaks at 16:00
AQI:
Medium
51.8/100
PM2.5 (fine particles):
Good
17.6/100
PM10 (coarse particles):
Good
11.9/100
NO2 (nitrogen dioxide):
Fair
32.9/100
O3 (ozone):
Medium
51.8/100
SO2 (sulfur dioxide):
Good
6.0/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Good
15.0/100
PM1 (ultrafine particles):
Good
12.6/100
Levels show the poorest local air quality during the day
Tomorrow - 17 July | Pollution peaks at 11:00
AQI:
Medium
43.8/100
PM2.5 (fine particles):
Good
17.5/100
PM10 (coarse particles):
Good
12.2/100
NO2 (nitrogen dioxide):
Fair
33.6/100
O3 (ozone):
Medium
43.8/100
SO2 (sulfur dioxide):
Good
3.5/100
CO (carbon monoxide):
Good
0.0/100
HCHO (formaldehyde):
Fair
21.4/100
PM1 (ultrafine particles):
Good
15.3/100
Pollen forecast in Siena
View pollen forecastFrequently Asked Questions
Is air quality bad in Siena right now?
On 16 July 2026, overall air quality in Siena is fair. NO2 is the main pollutant at 32.9/100. Pollution peaks around 4:00 PM (O3: 51.8/100).
Will air quality be worse tomorrow in Siena?
On 17 July 2026, air quality conditions in Siena will be similar to today, with NO2 forecast at fair at 33.6/100. Pollution peaks around 11:00 AM (O3: 43.8/100).
When is air pollution at its worst in Siena?
Siena residents notice reduced air quality mainly when below oak and linden pollen peaks, and during spells of significant car restrictions; otherwise, the area's setting generally supports clear, well-ventilated conditions.
Are air quality levels in Siena 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.
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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