English: Maritime traffic has a significative impact on air quality: ships generate emissions of sulphur oxides (SOx), nitrogen oxides (NOx), particulate matter (PM) and carbon dioxide (CO2) as a consequence of the composition of the fuel used to power them. In recent years, emissions have increased in a significative way, and as reported in a study commissioned by the International Maritime Organization (IMO), greenhouse gas emissions from shipping increased by 9.6% from 2012 to 2018, as rising demand outweighed efficiency improvements. This image shows the average value of Tropospheric Nitrogen Dioxide (NO2) detected between January and July 2020 by the Copernicus Sentinel-5P Satellite for the open water areas of the European Region (Mediterranean Sea, Atlantic Ocean, etc). In this visualisation, the "highway" that the vessels use to navigate the Strait of Gibraltar is easily visible because all the ships follow approximately the same route and reject a significative amount of NO₂ in the atmosphere. For the same reason (long stays at destination areas before unloading their cargo), the areas around port areas like Rotterdam, Marseille, Venice, Barcelona, etc. appear red in this visualisation. Nitrogen dioxide is a product of the combustion of fuels, in this instance from the burning of marine diesel and heavy fuel oil. Thanks to the TROPOMI instrument, that is onboard of the Copernicus Sentinel-5P Satellite, it is possible to see these shipping lanes with a spatial resolution of 7.5Km by 3.5 Km, a significant improvement when compared with the resolution of previous missions. The detection of NO2 concentrations in the atmosphere helps to monitor anthropogenic activities (notably fossil fuel combustion and biomass burning) and study natural processes (such as microbiological processes in soils, wildfires or lightning).