New National Ambient Air Quality Standards for Ozone: A Primer

Robin Kundis Craig

Oct. 7, 2015

Last week, the U.S. Environmental Protection Agency (EPA) finalized new National Ambient Air Quality Standards (NAAQS) for ozone pursuant to the federal Clean Air Act. See 42 U.S.C. § 7409. The new regulation reduces both the primary and secondary NAAQS for ozone from 0.075 to 0.070 parts per million (ppm) (or from 75 to 70 parts per billion) averaged over eight hours in order to better protect human health, welfare, and the environment. The new regulation has not yet been published in the Federal Register, but it is available from the EPA.

NAAQS are one of the Clean Air Act’s primary mechanisms for protecting human health and the environment from air pollution. Such protections begin with the EPA Administrator designating criteria pollutants—pollutants that, when emitted into the air, “cause or contribute to air pollution which may reasonably be anticipated to endanger public health or welfare,” that come from numerous or diverse sources, and for which the Administrator expects to issue air quality criteria.  42 U.S.C. § 7408(a)(1). Ozone has been a criteria pollutant under the Clean Air Act since the beginning of the 1970 Act’s implementation.

Once the EPA establishes criteria pollutants, it must set primary and secondary NAAQS for each of them. Primary NAAQS reflect the level of ambient air quality “requisite to protect the public health,” while secondary NAAQS protect the public welfare. 42 U.S.C. § 7409(b)(1), (2). Reflecting increased understanding of ozone pollution’s more pernicious effects on human health—for example, its role in heart disease—the EPA has been steadily ratcheting down the amount of ozone pollution that is legal. In 1979, for example, the primary NAAQS for ozone was 0.12 ppm; in 1997, the EPA revised it to 0.080 ppm; and in 2008 it revised the primary NAAQS to 0.075 ppm. This latest reduction in the ozone NAAQS reflects new scientific evidence that lower concentrations of ozone still affect human health. In particular, people with certain genetic variations and people who do not ingest enough antioxidants (vitamins C and E) are particularly at risk from ozone pollution, as are children, older adults, people with asthma, and people who work outdoors. Under courts’ interpretations of the Clean Air Act, the primary NAAQS must protect these most sensitive and most vulnerable populations.

Designating new NAAQS, however, imposes new obligations on states. In particular, any Air Quality Control Region that does not meets the new ozone NAAQS will be designated as being in nonattainment, requiring the relevant state to revise its State Implementation Plan (42 U.S.C. § 7410) to reflect new measures to bring these new nonattainment areas into compliance. Indeed, even as the EPA is establishing its new 2015 ozone NAAQS, many states are still working to attain the 2008 ozone standard, and some have not yet met the 1997 requirements.

Achieving the new ozone NAAQS will likely take a while in some places, particularly California. The EPA expects, based on 2012-2014 data, that 241 counties will not meet the new ozone standards. Initial nonattainment will be concentrated in the populated areas of the Southwest (California, Utah, Colorado, Arizona, and a few areas of New Mexico), coastal areas along the Great Lakes, and a swath along the Atlantic seaboard from Maryland to southern Maine, with more scattered areas of nonattainment elsewhere. However, the EPA also expects that most of these counties will be able to attain the new standards by 2025. California, however, presents a special case, and the EPA fully anticipates that several counties in southern California will still be in ozone nonattainment under the new standard after 2025.

The EPA expects to finalize designations of attainment and nonattainment areas for the revised ozone NAAQS in late 2017. “Marginal” nonattainment areas will probably have to attain the new NAAQS in either late 2020 or early 2021. “Moderate” nonattainment areas will probably have to reach attainment either in late 2023 or early 2024, while “serious” nonattainment areas (much of southern California) will probably have to meet the new NAAQS in late 2026 or early 2027.

In its regulatory impact analysis, the EPA estimates that the new ozone standard will cost $1.4 billion in 2011 U.S. dollars to implement by 2025 for everywhere but California; California alone adds another $0.80 billion in implementation costs. However, the EPA also expects the new rule to achieve $1.2 to $2.1 billion in health benefits in California and $2.9 to $5.9 billion in health benefits everywhere else, with the result that the health benefits achieved should greatly outweigh the costs of implementing the new standard. The specific health benefits that the EPA touts are largely the savings that result from avoiding death and sickness, including premature deaths from ozone and particulate matter, non-fatal heart attacks, hospital admissions, asthma attacks, and bronchitis, among others; it also factors in the benefits of avoiding work sick days, restrictions on activities, and missed school for children.

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