Community Air Pollution

by

Morton Lippmann

• LAST REVIEWED: 23 February 2011
• LAST MODIFIED: 23 February 2011
• DOI: 10.1093/obo/9780199756797-0003

Introduction

Human activities generate ambient air pollutants that we all inhale when outdoors. These pollutants also infiltrate the indoor microenvironments where people in developed countries typically spend about 90 percent of their time. Some of them, especially fossil fuel combustion effluents from motor vehicles and power plants, and their atmospheric transformation products, can produce adverse health effects. Pollutants of outdoor origin are present in complex mixtures. Their adverse effects (premature cardiopulmonary mortality, morbidity, lost time from work or school, functional impairment) are most closely associated with the concentrations of fine particulate matter (PM_2.5, that is, PM with aerodynamic diameters below 2.5 um), coarse thoracic PM (PM_10-2.5, that is, PM with aerodynamic diameters between 10 and 2.5 um), ozone (O₃), and nitrogen dioxide (NO₂). These air pollutants, plus sulfur dioxide (SO₂), carbon monoxide (CO), and lead (Pb), which historically have had numerous and widespread sources, are known as “criteria pollutants,” and are regulated in the United States in terms of ambient mass concentrations. Other air pollutants, which generally are emitted from more limited numbers of point sources and include known or suspected carcinogens, are known as “hazardous air pollutants” (HAPs) or air toxics. They are regulated in the United States by mass emission limits that have been selected to be conservative enough to prevent a significant number of people from suffering adverse health effects from them.

General Overviews

In the United States, the ambient concentrations of criteria air pollutants are routinely measured at urban and some rural sites selected to represent typical or upper-bound population exposures. The measurements are made using Federal Reference Methods (FRMs) or by methods that have been demonstrated to provide equivalent results (FEMs). The monitoring frequency varies. The gaseous pollutants are measured with continuous monitors, providing hourly as well as daily average concentrations, while particulate matter (PM) concentrations are typically determined by FRM analyses of samples collected on filters over twenty-four-hour periods. FEM methods for PM may provide better temporal resolution (Solomon, et al. 2008). The monitoring network for the airborne concentration data is used to determine compliance with the currently mandated National Ambient Air Quality Standards (NAAQS), as well as for epidemiological studies to determine exposure-response relationships that influence the periodic reexaminations, nominally at five-year intervals, of the adequacy of the NAAQS in terms of public health protection (Holgate 1999; Lippmann 2009). While the current NAAQS for NO₂, SO₂, and CO are seldom exceeded, those for PM_2.5 and O₃ are exceeded in many urban areas and some rural areas as well (Lippmann 2009). Furthermore, the current reexaminations of the NAAQS for PM_2.5 and O₃ are likely to lead to the establishment of more stringent NAAQS for these pollutants. The PM_2.5 is dominated by secondary PM, that is, PM formed in the atmosphere by chemical conversions of gaseous precursors, while the PM_10-2.5 is composed largely of primary PM, that is, dusts from windblown soil and natural plant and animal debris (Solomon, et al. 2008). Since 1999, the EPA monitoring network has included analyses of PM_2.5 chemical composition, and as of 2010 there are plans to begin speciation of the coarse PM fraction as well. Identification of the more toxic components of ambient air PM could provide a basis for their future regulation to supplement or replace the nonspecific PM NAAQS. The network for monitoring the concentrations of some HAPs is much newer and more limited in spatial coverage, and is not suitable for, or being used for, regulatory purposes; rather, it provides guidance on the adequacy of the air toxics emission limits (Schneider, et al. 1998). A wide range of topics related to these exposures and their health effects are reviewed in detail below by Lippmann, et al. 2003, Foster and Costa 2005, Ayres, et al. 2006, and Rom 2007.

• Ayres, Jon, Robert Maynard, and Roy Richards, eds. 2006. Air pollution and health. London: Imperial College Press.

  DOI: 10.1142/9781860949234

  This multiauthored review covers specific topics in depth: role of the nose, cardiovascular effects, effects of point source pollutants, mechanisms, acidic aerosols, test methods, and economic impact evaluation.

• Foster, W. Michael, and Daniel L. Costa, eds. 2005. Air pollutants and the respiratory tract. 2d ed. Boca Raton, FL: Taylor and Francis.

  This multiauthored review focuses on the effects of air pollution on the human respiratory tract, providing in-depth coverage.

• Holgate, Stephen T., Jonathan M. Samet, Hillel S. Koren, and Robert L. Maynard. 1999. Air pollution and health. San Diego: Academic Press.

  This authoritative and comprehensive, multiauthored review of air pollution history, determinants, health effects, associations with specific pollutants, cost impacts, standards, and risk communication, provides the most thorough broad review on the topic.

• Lippmann, Morton, ed. 2009. Environmental toxicants: Human exposures and their health effects. 3d ed. New York: Wiley.

  This multiauthored reference volume contains the first and most comprehensive in-depth series of reviews of the sources, human exposures, and biological responses to specific chemical and physical agents in the community environment that are known or likely to affect public health.

• Lippmann, Morton, Beverly S. Cohen, and Richard B. Schlesinger. 2003. Environmental health science: Recognition, evaluation and control of chemical and physical health hazards. New York: Oxford Univ. Press.

  This graduate-level textbook is the first to provide a technical overview of environmental media, contaminant sources, transport, fate, biological and environmental effects, exposure measurements, controls, risk assessment, and future prospects.

• Rom, William M., ed. 2007. Environmental and Occupational Medicine. 4th ed. Philadelphia: Lippincott, Williams and Wilkins.

  This comprehensive, multiauthored reference work reviews background information on occupational and environmental determinants of diseases, mechanisms, responses in organ systems, effects of a broad range of specific chemicals and physical agents in workplaces as well as in community air, study methodologies, and controls.

• Schneider, Toni, ed. 1998. Air pollution in the 21st century. Elsevier Studies in Environmental Science 72. Amsterdam: Elsevier.

  This topical multiauthored review focuses on particulate matter, persistent organic pollutants, ozone/NO_x, mobile sources and transport, economic impacts, and urban planning from an international perspective.

• Solomon, Paul A., Philip K. Hopke, John Froines, and Richard Scheffe. 2008. Key scientific findings and policy- and health-relevant insights from the US Environmental Protection Agency’s particulate matter supersites program and related studies: An integration and synthesis of results. Journal of the Air Waste Management Association 58:S3–S92.

  Summary of the findings of the very detailed multiyear studies of PM, its components, and chemical transformations carried out by research teams in Atlanta, Baltimore, Fresno, Houston, Los Angeles, New York City, Pittsburgh, and St. Louis. A thorough description of the complex chemistry in community air, and of how emitted pollutants are transformed into more toxic chemical species, subsequently neutralized, and removed to ground-level surfaces.