Use case: cities and regions

Monitoring air quality

Satellites measure nitrogen dioxide, ozone and other pollutants across whole regions, and the Copernicus Atmosphere Monitoring Service combines models with observations into daily forecasts for Europe. A city sees where pollution builds up and how it changes over time. Satellites do not replace ground stations: they observe the whole column of air, not the air at street level.

Reference
UC-06
Technologies
  • Earth observation
Industry
Challenge
Emissions and ESG reporting
Updated
Published by
LETO SPACE

01Technology

How satellites observe air pollution

Spectrometers on satellites measure sunlight reflected by the Earth's surface and atmosphere. Trace gases and aerosols leave spectral fingerprints in this light, and processing turns them into maps of pollutants such as nitrogen dioxide, sulphur dioxide and ozone Source: European Space Agency (ESA), 21 October 2025European Space Agency (ESA)Sentinel-4 offers first glimpses of air pollutants21 October 2025Open source (opens esa.int).

The satellite observes the whole column of air above a point. To estimate air quality near the ground, the Copernicus Atmosphere Monitoring Service (CAMS) combines observations from monitoring networks and satellites with atmospheric models Source: Copernicus Atmosphere Monitoring Service (CAMS), 8 May 2024Copernicus Atmosphere Monitoring Service (CAMS)CAMS role highlighted in the revised European Ambient Air Quality Directive8 May 2024Open source (opens atmosphere.copernicus.eu). Its European analysis merges model data with observations provided by the European Environment Agency Source: Copernicus Atmosphere Monitoring Service (CAMS), accessed 6 October 2026Copernicus Atmosphere Monitoring Service (CAMS)CAMS European air quality forecasts (Atmosphere Data Store, dataset overview)accessed 6 October 2026Open source (opens ads.atmosphere.copernicus.eu). For cities, EO-based services provide information on air quality in urban areas, including particles that can affect health Source: EU Agency for the Space Programme (EUSPA), 26 May 2026EU Agency for the Space Programme (EUSPA)EU Space Market Report 2026, Issue 126 May 2026Open source (opens euspa.europa.eu).

  • lowerhigherNitrogen dioxidein the column
  • Cloudno value
  • One pixelabout 5.5 by 3.5 km
  • Ground stationstays the basis
A satellite layer of nitrogen dioxide shows where pollution builds up across a region, in pixels of about 5.5 by 3.5 km. It describes the whole column of air, and clouds leave gaps. Ground stations measure the air at ground level and remain the basis. Illustrative map, not real data. Source: NASA Goddard Space Flight Center, Air Quality

02Data

Data and satellites

Sentinel-5P
Launched in October 2017; daily global coverage; resolution as high as 5.5 by 3.5 km since August 2019
Sentinel-4
Hourly scans of Europe and northern Africa; first images in October 2025, operational service expected in 2027
CAMS European forecasts
Daily analysis plus four-day forecast on a 10 km grid
Ground stations
Assimilated into the CAMS analysis and used to validate the main pollutants

Sentinel-5P provides information on trace gases, aerosols and clouds that affect air quality and climate, and covers the globe once a day Source: European Space Agency (ESA), accessed 6 October 2026European Space Agency (ESA)Sentinel-5P: Facts and figuresaccessed 6 October 2026Open source (opens esa.int). Since August 2019 its pixels measure about 5.5 by 3.5 km at nadir Source: NASA GES DISC, NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), accessed 8 October 2026NASA Goddard Earth Sciences Data and Information Services Center (GES DISC)Sentinel-5P TROPOMI Tropospheric NO2 1-Orbit L2 5.5km x 3.5km V2 (S5P_L2__NO2____HiR)accessed 8 October 2026Open source (opens disc.gsfc.nasa.gov). Sentinel-4 adds an hourly view from geostationary orbit. Its first images, published in October 2025, showed nitrogen dioxide, sulphur dioxide and ozone over Europe. Once operational, it will also map formaldehyde, glyoxal and aerosols, and its data will feed into CAMS Source: European Space Agency (ESA), 21 October 2025European Space Agency (ESA)Sentinel-4 offers first glimpses of air pollutants21 October 2025Open source (opens esa.int). EUMETSAT, which has operated the mission since September 2026, expects operational service to begin in 2027 Source: EUMETSAT, 28 September 2026EUMETSATEUMETSAT takes charge of Copernicus Sentinel-428 September 2026Open source (opens eumetsat.int).

The CAMS European forecasts cover nitrogen dioxide, ozone, sulphur dioxide, carbon monoxide, PM2.5, PM10 and pollen, among others. They are the median of an ensemble of regional models, which on average performs better than any single model. Only some species, among them nitrogen dioxide, ozone, PM2.5 and PM10, are regularly validated against ground measurements; the others are experimental Source: Copernicus Atmosphere Monitoring Service (CAMS), accessed 6 October 2026Copernicus Atmosphere Monitoring Service (CAMS)CAMS European air quality forecasts (Atmosphere Data Store, dataset overview)accessed 6 October 2026Open source (opens ads.atmosphere.copernicus.eu).

03Deliverables

What a city gets

The revised EU Ambient Air Quality Directive encourages Member States to use CAMS products for monitoring Source: Copernicus Atmosphere Monitoring Service (CAMS), 8 May 2024Copernicus Atmosphere Monitoring Service (CAMS)CAMS role highlighted in the revised European Ambient Air Quality Directive8 May 2024Open source (opens atmosphere.copernicus.eu). For a city, they are a recognised supplement to its own measurements, not a replacement for them.

04Limits

Limits

05Next steps

How we help

Copernicus air quality data is free of charge Source: European Union, EUR-Lex, 12 May 2021European Union, EUR-LexRegulation (EU) 2021/696 of 28 April 2021 establishing the Union Space Programme and the European Union Agency for the Space Programme12 May 2021Open source (opens eur-lex.europa.eu), so a city can start without buying data. The work lies in deciding which question the data should answer, which department uses the result, and whether a commercial service with finer detail is worth its price. In strategy and use cases we test the question against these points; in requirements and procurement we turn it into requirements that providers can answer.

To see which providers offer air quality services, Spacegraph, our discovery platform, has a use-case category "Emissions & air quality".

06Use cases

Frequently asked questions

Q1Which air quality data from space is available, and how often is it updated?

Sentinel-5P covers the whole globe once a day, around 13:30 local solar time Source: European Space Agency (ESA), accessed 6 October 2026European Space Agency (ESA)Sentinel-5P: Facts and figuresaccessed 6 October 2026Open source (opens esa.int). Sentinel-4 can scan Europe and northern Africa every hour Source: European Space Agency (ESA), 21 October 2025European Space Agency (ESA)Sentinel-4 offers first glimpses of air pollutants21 October 2025Open source (opens esa.int). EUMETSAT took over its operation in September 2026 and expects operational service to begin in 2027 Source: EUMETSAT, 28 September 2026EUMETSATEUMETSAT takes charge of Copernicus Sentinel-428 September 2026Open source (opens eumetsat.int). The Copernicus Atmosphere Monitoring Service publishes a daily analysis and forecasts for the next four days on a grid of about 10 km for Europe Source: Copernicus Atmosphere Monitoring Service (CAMS), accessed 6 October 2026Copernicus Atmosphere Monitoring Service (CAMS)CAMS European air quality forecasts (Atmosphere Data Store, dataset overview)accessed 6 October 2026Open source (opens ads.atmosphere.copernicus.eu). Copernicus services and data are free of charge Source: European Union, EUR-Lex, 12 May 2021European Union, EUR-LexRegulation (EU) 2021/696 of 28 April 2021 establishing the Union Space Programme and the European Union Agency for the Space Programme12 May 2021Open source (opens eur-lex.europa.eu).

Q2Can satellite data replace our air quality monitoring stations?

No. What a satellite observes is not the same as the concentration at ground level, and satellites that measure nitrogen dioxide cannot see through clouds Source: NASA Goddard Space Flight Center, Air Quality, 9 September 2026NASA Goddard Space Flight Center, Air QualityCaution advised on use and interpretation of satellite-derived nitrogen dioxide tropospheric columns9 September 2026Open source (opens airquality.gsfc.nasa.gov). Ground stations remain the basis. Models and satellite data add the picture between the stations: the revised EU Ambient Air Quality Directive asks for modelling, where applicable, so that point measurements can be read as a geographical distribution of concentrations Source: Copernicus Atmosphere Monitoring Service (CAMS), 8 May 2024Copernicus Atmosphere Monitoring Service (CAMS)CAMS role highlighted in the revised European Ambient Air Quality Directive8 May 2024Open source (opens atmosphere.copernicus.eu).

Q3How do we start a pilot?

Start with one question that a department owns, for example where to place a new sensor or how a traffic measure changes nitrogen dioxide over a district. We check which free Copernicus products already answer it, which commercial services add finer detail, and how to compare the results with your stations. Our consulting overview shows the path from the problem to the pilot.

Sources (9)

  1. European Space Agency (ESA), accessed 6 October 2026Sentinel-5P: Facts and figures (opens esa.int)
  2. NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), accessed 8 October 2026Sentinel-5P TROPOMI Tropospheric NO2 1-Orbit L2 5.5km x 3.5km V2 (S5P_L2__NO2____HiR) (opens disc.gsfc.nasa.gov)
  3. European Space Agency (ESA), 21 October 2025Sentinel-4 offers first glimpses of air pollutants (opens esa.int)
  4. EUMETSAT, 28 September 2026EUMETSAT takes charge of Copernicus Sentinel-4 (opens eumetsat.int)
  5. Copernicus Atmosphere Monitoring Service (CAMS), accessed 6 October 2026CAMS European air quality forecasts (Atmosphere Data Store, dataset overview) (opens ads.atmosphere.copernicus.eu)
  6. Copernicus Atmosphere Monitoring Service (CAMS), 8 May 2024CAMS role highlighted in the revised European Ambient Air Quality Directive (opens atmosphere.copernicus.eu)
  7. NASA Goddard Space Flight Center, Air Quality, 9 September 2026Caution advised on use and interpretation of satellite-derived nitrogen dioxide tropospheric columns (opens airquality.gsfc.nasa.gov)
  8. EU Agency for the Space Programme (EUSPA), 26 May 2026EU Space Market Report 2026, Issue 1 (opens euspa.europa.eu)
  9. European Union, EUR-Lex, 12 May 2021Regulation (EU) 2021/696 of 28 April 2021 establishing the Union Space Programme and the European Union Agency for the Space Programme (opens eur-lex.europa.eu)

Contact

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