This presentation spans more than 100 years of U.S. air pollution history in an effort to illuminate how we arrived at the particular approaches to managing air quality reflected in the Clean Air Act (CAA). Today, we can take pride in the remarkable progress and benefits that have come from the efforts of the many participants in U.S. air quality management, particularly since the passage of the landmark 1970 CAA Amendments. Analyses have found that the estimated benefits of the CAA substantially exceed compliance costs, and the ratio of benefits to costs has actually increased with time. Yet, the CAA has been far from perfect and implementation has been subject to numerous delays and inefficiencies.

Since 1970, air quality management in the United States has depended in large measure on establishing effects-based National Ambient Air Quality Standards (NAAQS) that drive state and local programs to attain and maintain acceptable air quality. But what were the origins of air quality standards and management, and how did the United States come to adopt this approach for federal legislation in 1970? Why not other approaches, such as leaving air pollution control to the states or local governments, setting best technology limits as in Germany, or adopting economic incentives such as emission taxes? In addition to shedding some light on these questions, the presentation will focus on how NAAQS were established and reviewed after 1970. It shows how the NAAQS have motivated implementation programs, motor vehicle standards, regional emissions reductions, and how NAAQS-inspired research in effects, air quality, and control sciences influenced policy and legislation that improved the effectiveness of air quality management. The presentation concludes by looking toward the future of air quality management, emphasizing continuing and new challenges, particularly how to coordinate with climate change programs.