This document discusses air pollution, its sources, effects, and methods of control. It defines air pollution as the presence of harmful materials in the air. The major sources of air pollution are burning fossil fuels, vehicle emissions, and industrial emissions from activities like steel production, fossil fuel power plants, and chemical plants. These sources release gases like carbon monoxide, nitrogen oxides, and sulfur dioxide that can harm human health and the environment. The document also outlines some approaches to control air pollution, such as installing pollution control devices, increasing chimney heights, limiting certain emissions and population growth, and planting more trees.