Sulfate, or SO4, is a chemical compound composed of sulfur and oxygen atoms. It is a constituent of rain and acid aerosols that are formed by the oxidation of sulfur dioxide (SO2) in the atmosphere. Sulfate particles can be formed naturally from volcanic eruptions, sea spray, and other sources, but they are also a major component of air pollution resulting from industrial activities, transportation, and power generation. When sulfate particles combine with other pollutants, such as nitrogen oxides, they can contribute to the formation of fine particulate matter, which can have negative impacts on human health and the environment. Sulfate particles can also affect the Earth’s climate by scattering and absorbing radiation, which can influence cloud formation and atmospheric temperatures. Overall, SO4 is an important environmental pollutant that requires continued monitoring and management to minimize its impacts on human health and the environment.