In celebration of the 100th anniversary of the Air & Waste Management Association, this review examines the history of air quality management (AQM) in the United States over the last century, with an emphasis on the ambient standards programs established by the landmark 1970 Clean Air Act (CAA) Amendments. The current CAA system is a hybrid of several distinct air pollution control philosophies, including the recursive or circular system driven by ambient standards. Although this evolving system has resulted in tremendous improvements in air quality, it has been far from perfect in terms of timeliness and effectiveness. The paper looks at several periods in the history of the U.S. program, including: (1) 1900–1970, spanning the early smoke abatement and smog control programs, the first federal involvement, and the development of a hybrid AQM approach in the 1970 CAA; (2) 1971–1976, when the first National Ambient Air Quality Standards (NAAQS) were set and implemented; (3) 1977–1993, a period of the first revisions to the standards, new CAA Amendments, delays in implementation and decision-making, and key science/policy/legislative developments that would alter both the focus and scale of air pollution programs and how they are implemented; and (4) 1993–2006, the second and third wave of NAAQS revisions and their implementation in the context of the 1990 CAA. This discussion examines where NAAQS have helped drive implementation programs and how improvements in both effects and air quality/control sciences influenced policy and legislation to enhance the effectiveness of the system over time. The review concludes with a look toward the future of AQM, emphasizing challenges and ways to meet them. The most significant of these is the need to make more efficient progress toward air quality goals, while adjusting the system to address the growing intersections between air quality management and climate change.
The celebration of the 100th anniversary of the Air & Waste Management Association occurs at an important juncture for U.S. air pollution programs. The year 2006 marked the 35th anniversary of the National Ambient Air Quality Standards (NAAQS).1 The year before that was the 35th anniversary of the formation of the U.S. Environmental Protection Agency (EPA)2 and the passage of the landmark 1970 Clean Air Act (CAA) Amendments.3 This law established the air quality management (AQM) framework that is in use today. Although much has changed since then, the fundamental approach of the 1970 CAA was to formalize the broad outlines that define the respective roles and responsibilities of the major participants. The process was designed to result in continuing improvements over time, and it has: in terms of the pollutants the 1970 CAA addressed, U.S. air quality over the years is demonstrably and markedly improved (e.g., Figure 1). On the other hand, the process has been far from perfect in timeliness and effectiveness, and a number of important air quality related challenges remain.4 Furthermore, EPA recently announced changes to the approach used over the last 25 yr to review and revise the NAAQS5 and an Agency advisory panel has just completed work on a series of recommendations for improving AQM.6,7 This is a good time to look at the history of U.S. AQM.