Pollution par le NO2, vue par Envisat (ESA/Sciamachy)

Based on 18 months of Envisat observations, this high-resolution global atmospheric map of nitrogen dioxide pollution makes clear just how human activities impact air quality.

ESA's ten-instrument Envisat, the world's largest satellite for environmental monitoring, was launched in February 2002. Its onboard Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) instrument records the spectrum of sunlight shining through the atmosphere. These results are then finely sifted to find spectral absorption 'fingerprints' of trace gases in the air. Nitrogen dioxide (NO2) is a mainly man-made gas, excess exposure to which causes lung damage and respiratory problems. It also plays an important role in atmospheric chemistry, because it leads to the production of ozone in the troposphere – which is the lowest part of the atmosphere, extending up to between eight and 16 kilometres high.