Air pollution is the introduction of particulates, biological molecules, or other harmful materials into earth's atmosphere, causing diseases, allergies, death to humans, damage to other living organisms such as animals and food crops, or the natural or built environment.
Along with harming human health, air pollution can cause a variety of environmental effects: Acid rain is precipitation containing harmful amounts of nitric and sulfuric acids.
Air pollution includes greenhouse gases like carbon dioxide, hydrocarbon ( methane) etc. It causes global warming by trapping heat from the Sun in the Earth's atmosphere.