A suspension of solid or liquid particles in the air with a typical size from a few nanometers to 10 μm that lingers in the atmosphere at least several hours. The term aerosol, which includes both particles and suspended gas, is often used in the plural in this report to mean aerosol particles. Aerosols can be either natural or  anthropogenic  origin. Aerosols can affect climate in several ways: through interactions that scatter and/or absorb radiation, and through interactions with cloud microphysics and other cloud properties, or when deposited on snow- or ice-covered surfaces, changing their albedo and contributing to climate   reverse bonds. Atmospheric aerosols, whether natural or anthropogenic, originate from two different pathways: emissions of primary particulate matter (PM) and formation of secondary PM from gaseous precursors . Most aerosols are of natural origin. Some scientists use group designations that refer to chemical composition, namely: sea salt, organic carbon, black carbon (BC), mineral species (mainly desert dust), sulfate, nitrate and ammonium. However, these labels are imperfect because aerosols bind particles together to form complex mixtures.