Worst air pollution Sintra, today and tomorrow

Today (21 July): Air quality in Sintra is medium. AQI and O3 are medium; PM2.5, PM10, NO2, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 3:00 PM (O3: 42.7/100).
Tomorrow (22 July 2026): Air quality in Sintra is fair. AQI worsens to fair; O3 increases to fair; all other pollutants stay as today. Pollution peaks around 12:00 PM (O3: 33.7/100). 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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Sintra's air quality benefits from its elevated position on the Sintra-Cascais Natural Park ridge northwest of Lisbon, with consistent Atlantic Ocean airflows providing outstanding clean maritime ventilation across the UNESCO-listed wooded hillside. This is consistently one of the Lisbon region's cleanest locations, with the combination of elevation, Atlantic exposure, and the natural park's extensive forest cover providing rural air quality character throughout the year.

Today - 21 July | Pollution peaks at 15:00

AQI:

Medium

42.7/100

PM2.5 (fine particles):

Good

15.1/100

PM10 (coarse particles):

Good

11.6/100

NO2 (nitrogen dioxide):

Good

12.2/100

O3 (ozone):

Medium

42.7/100

SO2 (sulfur dioxide):

Good

2.0/100

CO (carbon monoxide):

Good

0.0/100

HCHO (formaldehyde):

Good

9.3/100

PM1 (ultrafine particles):

Good

10.1/100

Levels show the poorest local air quality during the day

Tomorrow - 22 July | Pollution peaks at 12:00

AQI:

Fair

33.7/100

PM2.5 (fine particles):

Good

15.6/100

PM10 (coarse particles):

Good

12.9/100

NO2 (nitrogen dioxide):

Good

5.9/100

O3 (ozone):

Fair

33.7/100

SO2 (sulfur dioxide):

Good

2.0/100

CO (carbon monoxide):

Good

0.0/100

HCHO (formaldehyde):

Good

3.2/100

PM1 (ultrafine particles):

Good

10.2/100

Pollen forecast in Sintra

View pollen forecast

Frequently Asked Questions

Is air quality bad in Sintra right now?

On 21 July 2026, overall air quality in Sintra is medium. AQI is the main air quality indicator at 42.7/100. Pollution peaks around 3:00 PM (O3: 42.7/100).

Will air quality be worse tomorrow in Sintra?

On 22 July 2026, air quality conditions in Sintra will be worse than today, with AQI forecast at fair at 33.7/100. Pollution peaks around 12:00 PM (O3: 33.7/100).

When is air pollution at its worst in Sintra?

Residents in Sintra are likeliest to notice reduced air quality when local combined tree and grass pollen peaks, or due to the combination of; for the rest of the calendar year, natural airflow keeps background levels low.

Are air quality levels in Sintra 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: 21 July 2026 at 10:44 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