What is NO₂?
A gas released when fuel burns, in ship engines, vehicles and industry. It stays close to its source, so it maps where combustion happens.
What does the satellite measure?
Sentinel-5P scans the whole planet daily and measures the NO₂ column below it. We use the official 2024 annual mean, cell by cell (~2 km).
What does "enhancement" mean?
How much more NO₂ sits over the port (±15 km) than over its own region (60–120 km ring). +50% = half again as much as the regional norm.
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Ports and lanes analysed
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Strongest enhancement
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Strait of Gibraltar vs background
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Cleanest port signal
NO₂ enhancement over the regional background, 2024
Port pixel (±15 km) versus surrounding ring (60–120 km). Green: ports away from big cities, where the signal is mostly maritime and port activity. Amber: ports inside metropolitan areas, where city traffic and industry also contribute. Blue: open-sea shipping lanes, no city at all.
What the groups tell us
Average enhancement per setting, computed from the table below
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Shipping lanes (no city)
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Ports away from cities
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Metropolitan port regions
Absolute levels: port versus its own region
Tropospheric NO₂ column, 10¹⁵ molecules/cm². The pair shows both the level and the local excess; Rotterdam has the highest absolute level, but sits in an already-polluted region.
Full results
| Target | Setting | NO₂ over target (10¹⁵ molec/cm²) | Regional background | Enhancement |
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