Satellite observations of air quality, climate and volcanic eruptions

Nitrogen oxides (NOx, the collective name for NO and NO2) play an important role in atmospheric chemistry and in the climate system as precursor of tropospheric ozone, an important greenhouse gas. The most important source of NOx is the combustion of fossil fuels, mainly by traffic and large power plants. Other important contributors are the burning of biomass, soil emissions and lightning. Close to the earth surface the lifetime of NOx is short (a few hours). Therefore, NO2 concentrations will be highest close to the source. Nitrogen oxides affect the health of humans and animals. They irritate the lungs and lead to lower resistance to respiratory infections such as influenza. Frequent exposure to high concentrations may cause acute respiratory illness. Another serious problem caused by nitrogen oxides is the formation of aerosols and tropospheric ozone (i.e. smog), which has also harmful health effects. In addition, increasing tropospheric ozone affects climate.