ABSTRACT
This chapter discusses two of the six common air pollutants-particulate matter and lead. Particulate matter is examined in Section 9.1 through Section 9.7, whereas lead is presented in Section 9.8. Particle pollution, also called particulate matter or PM, refers to a mixture of solid particles and liquid droplets found in the air. The physical dimensions and chemical properties of these aerosols vary greatly. Their size may vary from 0.5 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 from different sources, and the potential adverse effects they can cause, 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 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 speci¤c examples of PM: silica, beryllium, and asbestos.
