ABSTRACT
Particulate air pollution refers to the presence of small solid and liquid aerosols suspended in the atmosphere. The physical dimensions and chemical properties of these aerosols vary greatly. Their sizes may vary from 0.5 mm to 10−7 mm, and they are composed of a large number of inorganic and organic materials, including metals and nonmetal elements (and their oxides, nitrates, and sulfates). Although it is often convenient to group them as particulates, their sources, distribution, and effects can be highly variable. Because of the large quantities of particulates emitted into the atmosphere and the potential adverse effects they elicit, the U.S. Environmental Protection Agency (EPA) has designated particulate matter (PM) as one of the six “Criteria Air Pollutants” to be regulated. In 1987, the agency added a new standard for particulates, called PM10 (referring to PM with a diameter less than 10 µm), based on the evidence that the smaller PM has the greatest impact on health because of its capacity to be inhaled. This chapter presents an overview of this class of air pollutants, followed by discussion of three specific examples of PM: silica, beryllium, and asbestos.
