The atmosphere is a dynamic mixture of various gases surrounding the Earth. Air pollution refers to the presence of harmful gases or undesirable particles in concentrations enough to inflict harmful effects on all organisms (plants, animals, and microorganisms), human health and socioeconomic systems, and historical buildings and monuments. Air pollutants are broadly classified as stationary sources and mobile sources. The stationary sources of air pollution are fixed at one location emitting pollution from a particular identifiable point. These sources are further divided into point sources and nonpoint or area sources. Mobile sources, because of their extensive mobility, are extremely vigorous sources of air pollution over the very large areas they cover moving from one place to other distant places. These sources can be categorized into line sources and area sources. The other significant sources of air pollution include agriculture, ionizing radiations, suspended particulate matter (SPM), and households (indoor pollution). Radiation of short wavelength of the electromagnetic spectrum—Gamma rays, X-rays, and higher energy ultraviolet (UV) rays—is called ionizing radiation. The ionizing radiation carries energy enough to ionize atoms or molecules by detaching electrons. Subatomic particles created by radioactive decay—viz. alpha and beta particles, and neutrons—also fall into the category of ionization radiation. SPM dispersed into air is produced due to anthropogenic activities like combustion processes, agricultural practices, mining operations, industrial processes and natural processes, such as dust storms, volcanic eruptions, and sea sprays, and biological contaminants. Detergents, shoe polish, hair dyes, cleaners, paints, varnishes, asbestos, cosmetic products, deodorants, insecticides, rodenticides, mosquito repellents, and many other chemicals are the various sources of indoor pollution.