The document discusses the composition of air and various types of air pollution. It identifies major air pollutants like carbon monoxide, oxides of nitrogen, and sulfur dioxide. Carbon monoxide is produced during incomplete combustion of fuels and binds to hemoglobin in blood. Oxides of nitrogen form at high engine temperatures or during lightning. Sulfur dioxide is released from burning fossil fuels. These pollutants can cause health effects and form acid rain by reacting with water vapor in the atmosphere. Acid rain damages buildings, plants, and aquatic ecosystems.