Federal and State Perspectives on National Ambient Air Quality Standards

EM—September 2018: An overview of the U.S. Clean Air Act (CAA) National Ambient Air Quality Standards (NAAQS) program, with author contributions from the federal government and three state associations.
by John Kinsman

This issue presents federal and state perspectives on NAAQS issues. In the first article, Alexander Dominguez and Clint Woods of EPA discuss the agency's efforts to review and reform the NAAQS program, including a “back-to-basics” approach for NAAQS standard setting, designations, and implementation. An April 2018 Presidential memorandum is reviewed, which set forth nine primary directives intended to ensure EPA's efficient and cost-effective implementation of air quality standards and regional haze programs. Timeliness, cooperative federalism (working with state co-regulators), and recognition of international and background sources of pollution are critical issues the agency is directed to address.

The authors also discuss EPA's May 2018 memorandum, Back-to-Basics Process for Reviewing National Ambient Air Quality Standards, which directs the agency and its independent science advisors to follow five principles for a transparent, timely, and efficient process in reviewing and revising future public health- and welfare-based NAAQS. The authors present important milestones in implementing NAAQS, such as goals for reducing the number of non-attainment areas, reducing the backlog in state plan submissions, and actions related to exceptional events, international sources, interstate transport, state plans, etc.

In the next article, Jason Sloan, Stuart Spencer, and Nancy Vehr of AAPCA (a national organization of more than 20 state environmental agencies and additional local air agencies) focus on air quality improvements in the United States, and the role of states and local air agencies responsible for implementing the NAAQS through the CAA's framework of cooperative federalism. In April 2017, AAPCA published the inaugural edition of The Greatest Story Seldom Told: Profiles and Success Stories in Air Pollution Control, an annual report that highlights air quality trends, and underscores the critical role of state and local air agencies in making complex regulatory decisions impacting their communities. The 2018 edition of AAPCA's report, published in July, includes updated trends for criteria pollutant concentrations and emissions that show continued progress.

The authors discuss opportunities for continued air quality success as state and local agencies continue to work toward attaining national standards and characterizing air quality. AAPCA-conducted surveys of state environmental agency comments recognized several common concerns when it comes to establishing compliance with new NAAQS. For example, of 44 state environmental agencies that filed individual comments, 26 state agencies raised background ozone (O3) as an achievability or implementation challenge, including both naturally occurring and internationally transported contributions to ground-level O3. The authors state that continued success is dependent on informed collaboration at the federal, state, and local levels.

Next, Miles Keogh of NACAA (a national association of 156 state and local air pollution control agencies in 41 states, the District of Columbia, and four territories) observes that since 1970, the United States has made tremendous strides in reducing levels of the criteria pollutants for which NAAQS are established, driven by the scientific evidence that there are serious health consequences associated with exposure to these pollutants. The article then focuses on EPA's April 30 proposed rule, “Strengthening Transparency in Regulatory Science.” While EPA has stated that its intent with the proposed rule is to increase the quality and transparency of the agency's decision-making, the author says that it is possible that the provisions of the science proposal would weaken both, and many unknowns remain that should be fleshed out.

Further, while there is a laudable long-term trend toward increased transparency in science, complete public access to underlying data is not always
possible, especially in the case of epidemiological studies based on private health data that must remain confidential. The author concludes by observing that the NAAQS remain a key component of the hard-won clean air gains of recent decades, and diminishing the science used to understand the health implications that drive these standards would harm the health of Americans.

The final article by Mary Uhl of WESTAR and Tom Moore of WRAP (a forum of 15 western states and federal land management partners, and a partnership of states, tribes, federal land managers, local air agencies, and EPA, respectively) addresses NAAQS implementation issues in the Western United States, especially background O3 and O3 transport issues. As the O3 NAAQS have changed in form and stringency over the past two decades, rural areas with high concentrations of O3 and low numbers of local sources likely responsible for elevated O3 concentrations have brought a new focus on the analysis of transport, uncontrollable sources of O3 precursors and background O3. Western planning needs also include identification of O3 exceptional events, and clarification of the application of planning mechanisms offered in the CAA (i.e., international transport in Sec. 179B Demonstrations and Sec. 182 Rural Transport Areas).

The authors observe that EPA's funding support in the East has advanced understanding by eastern states of the origin of O3 precursors, O3 formation and the fate of O3, which helped with the development andimplementation of meaningful and effective regulatory programs to improve air quality. Western states need a better understanding of the origin of O3 precursors, photochemical activity, and fate of transported O3 to develop and implement effective regulatory programs. ....