This document discusses air pollution, its causes, effects, and ways to control it. Air pollution occurs when harmful substances such as particulates and biological molecules are released into the atmosphere from both natural sources like volcanoes and forest fires, as well as human sources like vehicle and industrial emissions. It can harm human health by causing diseases and death, and also damage plants, animals, and materials. To control air pollution, regulations limit emissions from vehicles and factories, communities can plant trees and use less private vehicles, and governments can enforce laws while increasing environmental awareness.