Abstract

Air pollution is defined as the presence in the outdoor atmosphere (ambient air) of one or more contaminants in such quantities and for such duration as to be harmful or injurious to human health or welfare, animal or plant life, or property, or may unreasonably interfere with the enjoyment of life or property. It is useful to study the causes and sources of the various air pollutants, as well as their physical and chemical characteristics and these are discussed. There are many different air pollutants, all with differing physical and chemical characteristics, as well as a vast number and variety of air pollution sources. Therefore, a good understanding of the pollutants and their sources is necessary before a particular control technology can be selected for best application to any particular situation.

Some of the most common pollutants have been well known for decades, and continue to be emitted at rates exceeding millions of tons per year (in the United States alone). These “traditional” air pollutants include particulate matter (PM), sulfur oxides (SO_x), nitrogen oxides (NO_x), volatile organic compounds (VOCs), and carbon monoxide (CO). Another major pollutant is ground-level ozone (O₃). Ozone is not emitted directly; rather it is formed by photochemical reactions in the atmosphere between NO_x and VOCs. Other important pollutants include lead (as leaded gasoline was phased out in the 1980s, the U.S. emissions of lead into the atmosphere dropped by 95% or more), hazardous air pollutants (HAPs), including lead, mercury, formaldehyde, benzene, and many others, several ozone-depleting compounds (such as chlorofluorocarbons), and greenhouse gases, such as carbon dioxide (CO₂) and methane (CH₄). A brief review of the pollutants is presented here. Air pollution regulations are discussed. Sampling and control of air pollution is detailed. This includes information on the control of gaseous emissions, particulate matter emissions and mobile source emissions. Methods and sampling for control of odors is included.