Emissions of air pollutants have a wide range of effects in the environment. Poor air quality can affect human health, while deposition of air pollutants back to earth can affect ecosystems, changing biodiversity and reducing water quality. Air pollutants are removed from the atmosphere through ‘wet deposition’, by rain, snow and fog, and by ‘dry deposition’, which is the direct uptake of gases and particles to land and water surfaces. The key components relevant for atmospheric deposition are sulphur, reactive nitrogen, chlorine, base cations and heavy metals. This site provides UK information on atmospheric deposition, as supported by Defra and the UK Devolved Administrations. It complements UK-AIR, which focuses on air pollutant concentrations and human health, and UKREATE, which addresses the impacts of air pollution on terrestrial ecosystems.