ABSTRACT
Air pollution refers to the introduction of physico-chemical or biological materials into the atmosphere that may cause harm or discomfort to humans or other living organisms, or deterioration of the natural environment. The ambient and indoor air composition has a considerable impact on our health and quality of life. Air pollution and greenhouse gas emissions can have a considerable impact on the environment, including broader global environmental issues such as stratospheric ozone depletion and climate change. Air pollutants can be broadly classied as either primary or secondary. Usually, primary air pollutants are substances that are directly emitted from a natural or anthropogenic process, such as ash from a volcanic eruption, carbon monoxide (CO) gas from motor vehicle exhaust, or sulfur dioxide (SO2) released from factories. However, primary pollutants do not, by themselves, produce all of the adverse effects of air pollution. Chemical reactions may occur among primary pollutants and constituents of the atmosphere, as illustrated in Figure 2.1. Subsequently, gaseous pollutants reacting with each other and with particles in the air produce a complex array of new chemical compounds. Air pollutants not directly emitted as such, but formed in the air, are called secondary air pollutants, which are responsible for several ill effects of air pollution such as smog, haze, eye irritation, and damage to vegetation and material.
