Worst air pollution Seixal, today and tomorrow
Today (20 September): Air quality in Seixal is good. AQI, PM2.5, PM10, NO2, O3, SO2, CO, HCHO, and PM1 are good. Pollution peaks around 5:00 PM (O3: 16.6/100).
Tomorrow (21 September 2026): Air quality in Seixal is good. All pollutants stay as today. Pollution peaks around 5:00 PM (O3: 17.3/100). 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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Seixal's air quality reflects its position on the southern bank of the Tagus estuary opposite Lisbon, with the Seixal industrial zone's steel and chemical operations and heavy traffic on the A2 contributing elevated PM2.5 and SO₂. The Tagus estuary generally provides ventilation from Atlantic westerlies, while the Arrábida Natural Park to the south provides a clean-air backdrop, and the prevailing northwesterly winds over the estuary generally carry Lisbon's urban emissions southward toward the Seixal and Almada shoreline.
Today - 20 September | Pollution peaks at 17:00
AQI:
Good
16.6/100
PM2.5 (fine particles):
Good
9.7/100
PM10 (coarse particles):
Good
14.2/100
NO2 (nitrogen dioxide):
Good
7.1/100
O3 (ozone):
Good
16.6/100
SO2 (sulfur dioxide):
Good
1.3/100
CO (carbon monoxide):
Good
0.6/100
HCHO (formaldehyde):
Good
3.2/100
PM1 (ultrafine particles):
Good
8.1/100
Levels show the poorest local air quality during the day
Tomorrow - 21 September | Pollution peaks at 17:00
AQI:
Good
17.3/100
PM2.5 (fine particles):
Good
9.9/100
PM10 (coarse particles):
Good
14.2/100
NO2 (nitrogen dioxide):
Good
6.7/100
O3 (ozone):
Good
17.3/100
SO2 (sulfur dioxide):
Good
1.2/100
CO (carbon monoxide):
Good
0.6/100
HCHO (formaldehyde):
Good
3.5/100
PM1 (ultrafine particles):
Good
8.6/100
Pollen forecast in Seixal
View pollen forecastFrequently Asked Questions
Is air quality bad in Seixal right now?
On 20 September 2026, overall air quality in Seixal is good. AQI is the main air quality indicator at 16.6/100. Pollution peaks around 5:00 PM (O3: 16.6/100).
Will air quality be worse tomorrow in Seixal?
On 21 September 2026, air quality conditions in Seixal will be similar to today, with AQI forecast at good at 17.3/100. Pollution peaks around 5:00 PM (O3: 17.3/100).
When is air pollution at its worst in Seixal?
People in Seixal tend to notice reduced air quality when estuary pine and eucalyptus pollen peaks, or because of the Seixal industrial zone's steel and chemical operations and heavy traffic on the A2; conditions usually ease once the wet season or windier weather returns.
Are air quality levels in Seixal 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: 20 September 2026 at 14:33 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.
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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