This document discusses various types of air pollution including their sources and effects. It defines air pollution as atmospheric conditions produced by certain substances in concentrations that adversely affect humans and the environment. The major sources of air pollution include natural sources like volcanoes and man-made sources such as factories and automobiles. Primary pollutants are emitted directly while secondary pollutants form when primary pollutants interact chemically or physically in the air. The document outlines several primary and secondary air pollutants and their health effects. It concludes with some measures that can be taken to reduce air pollution.