Air pollution is a worldwide problem especially in many big cities and industrial areas around the world. Emission of fine particulate matter (e.g. aerodynamic diameter ≤ 2.5 µm; PM2.5) , chemicals (e.g. biogenic VOC) and pollutants (e.g. heavy metals), and associated photo-chemical reactions (e.g. production of tropospheric ozone) in the atmosphere as well as in-cloud interactions (e.g. acid rain) experienced dramatic changes since the industrial revolutions. Concentrations of hazardous pollutants in global atmospheric air masses, dry and wet precipitates have been subject to gradual increasing reaching harmful levels for air-quality what regards human health (e.g. lung cancer, mortality) and the environment (e.g. negative impacts for forests and vegetation and quality of life in aquatic eco-systems) in many places around the world.
Climate change influences air quality through several mechanisms, including changes in photochemical reaction rates, biogenic emissions, deposition/re-suspension, and atmospheric circulation. Several techniques/approaches were used in such studies including atmospheric chemistry, climate model inter-comparison, high-resolution satellite observations together with a global atmospheric models and extensive compilation of surface measurements to better represent global air pollution exposure.