Ambient Air Quality Standards and Guidelines

by

Morton Lippmann

• LAST REVIEWED: 23 February 2011
• LAST MODIFIED: 23 February 2011
• DOI: 10.1093/obo/9780199756797-0005

Introduction

The inhalation of ambient air pollutants is significantly associated with excess mortality, morbidity, lost time from school and work, and loss of cardiopulmonary function. Quantitative information on the relationships between airborne concentrations and their health effects specify the limits on air quality that prevent such effects (when there are thresholds for response), or are at a level that is acceptable to society (when there is no threshold, that is, where there are linear relationships between exposure and response). Such limits may be legally mandated, as the National Ambient Air Quality Standards (NAAQS), in the United States, or provide technical advice to governmental agencies that can be used in setting standards, such as that provided in the Air Quality Guidelines (AQGs) of the World Health Organization (WHO). Alternatively, exposures can be controlled by emission standards for known toxicant sources, such as those for motor vehicles and point sources of industrial effluents. For air pollution, as well as other toxicants that affect human health, effective public health protection relies on standards that guide actions taken to limit exposures. For community air pollution in the United States, these take the form of NAAQS for six pollutants or pollutant classes that originate from numerous and widespread sources, that is, particulate matter (PM), photochemical oxidants, as indexed by ozone (O₃), nitrogen oxides, as indexed by nitrogen dioxide (NO₂), sulfur oxides, as indexed by sulfur dioxide (SO₂), carbon monoxide (CO), and lead (Pb). There are also National Emission Standards for Hazardous Air Pollutants (NESHAPS) for air pollutants arising from identifiable point sources.

General Overviews

In the United States, as a national example, the Environmental Protection Agency (EPA) is required, under the provisions of the Clean Air Act (CAA), to set National Ambient Air Quality Standards (NAAQS), that is, ambient air concentration limits, for air pollutants arising from numerous and widespread sources. The achievement of such limits is the responsibility of the state governments through State Implementation Plans (SIPS) that deal with source controls. SIPs require EPA approval. The CAA also mandates that the EPA reconsider the NAAQS every five years, with the formal participation of an external scientific advisory committee appointed by the EPA Administrator, that is, the Clean Air Scientific Advisory Committee (CASAC). The CAA also mandates the setting of emission standards for motor vehicles and power plants burning fossil fuels as a means of reducing ambient air concentrations of criteria pollutants, as well as National Emission Standards for Hazardous Air Pollutants (NESHAPS) that are emitted from a limited number of point sources. Many smaller and/or less developed countries, lacking the scientific and/or financial resources of the United States or Europe, rely on guidance from WHO to assist them in setting their own national standards. Some may act collectively in setting standards that apply in a group of countries, as in the European Community), recognizing that air pollutants do not respect borders and to harmonize regulations in common markets. For developing counties with severe air pollution problems, the WHO provides interim guidelines as well as long-term goals for clean air that would protect nearly all people. Adherence to the interim guidelines would reduce the public health impact and encourage further progress toward meeting the long-term goals. Historical perspectives on the development of these standards were prepared by Lippmann 1987, Lippmann 2005, and Bachmann 2007. For other countries, generally those with fewer resources for standards development, guidelines promulgated by the World Health Organization (WHO) are used as a basis for the development of their own national standards (World Health Organization 1987, World Health Organization 2000, World Health Organization 2006). These guidelines are discussed in detail in World Health Organization Guidelines.

• Bachmann, John. 2007. Will the circle be unbroken: A history of the U.S. National Ambient Air Quality Standards. Journal of the Air Waste Management Association 57:652–697.

  DOI: 10.3155/1047-3289.57.6.652

  A comprehensive historical review of the complex process by which NAAQS for criteria air pollutants are established and maintained in the United States that was prepared by a recently retired EPA staff member who was particularly influential in the development of the NAAQS.

• Hubbell, Bryan J., Richard V. Crume, Dale M. Evarts, and Jeff M. Cohen. 2009. Regulation and progress under the 1990 Clean Air Act Amendments. Review of Environmental Economics and Policy 4:127–138.

  A perspective on the progress and status of ambient air quality as impacted by the requirements mandated by the latest (1990) revisions of the Clean Air Act, including the important role of the National Emission Standards for Hazardous Air Pollutants (NESHAPS) in achieving compliance with the NAAQS, as seen from within EPA.

• Lippmann, Morton. 1987. Role of science advisory groups in establishing standards for ambient air pollutants. Aerosol Science and Technology 6:93–114.

  DOI: 10.1080/02786828708959124

  A review of the need for, establishment of, and the evolving critical role played by the legally mandated Clean Air Scientific Advisory Committee (CASAC) in the evolution of the procedures followed by EPA in the development and promulgation of NAAQS for criteria pollutants.

• Lippmann, Morton. 2005. Air pollution: Public health and regulatory considerations. In Air pollutants and the respiratory tract. 2d ed. Edited by W. Michael Foster and Daniel L. Costa, 405–441. Boca Raton, FL: Taylor and Francis.

  An updated historical review of the development of NAAQS and WHO Guidelines for community air pollutants.

• World Health Organization Regional Office for Europe. 1987. Air quality guidelines for Europe. Copenhagen: World Health Organization Regional Office for Europe.

  The first official WHO guidance for air quality goals for the protection of human health. It covered exposures to twelve organic air pollutants, twelve inorganic air pollutants, as well as exposures for NO₂, O₃, SO₂, and PM. It was focused on the needs of the nations of eastern and western Europe.

• World Health Organization Regional Office for Europe. 2000. Air quality guidelines for Europe. 2d ed. Copenhagen: World Health Organization Regional Office for Europe.

  This second edition of official WHO guidance for air quality goals addressed the protection of human health from exposures to sixteen organic air pollutants, eleven inorganic air pollutants, as well as for NO₂, O₃, CO, SO₂, and PM. This edition continues to focus on the needs of nations in Europe.

• World Health Organization Regional Office for Europe. 2006. Air quality guidelines global update 2005: Particulate matter, ozone, nitrogen dioxide, and sulfur dioxide. Copenhagen: World Health Organization Regional Office for Europe.

  This WHO update on Air Quality Guidelines provides a comprehensive review, from a worldwide perspective. It includes background chapters on sources of air pollution, concentrations and trends, human exposures, health effects, determinants of susceptibility, environmental equity, impact assessment, policy formulation, and indoor air quality, as well as detailed reviews and updated recommendations for Guidelines on PM, O₃, NO₂, and SO₂.