Air pollution is a mixture of solid particles and gases that can have negative health effects. It comes from both natural sources like wildfires and dust, as well as human sources such as vehicles, factories, and burning fuels. Major pollutants include carbon dioxide, carbon monoxide, sulfur dioxide, and nitrogen dioxide. Air pollution causes problems through both primary mechanisms of direct emission and secondary mechanisms of chemical reactions. It can cause respiratory diseases and other health issues as well as environmental damage. Prevention efforts focus on reducing emissions through sustainable technologies, international agreements, and changes to individual lifestyles.