Updated: 6/1/2024

Ground-level ozone (O₃) is a “criteria pollutant” identified by the federal Clean Air Act (“CAA”) for which EPA is required to establish National Ambient Air Quality Standards (“NAAQS”) to protect human health and welfare. Ground-level ozone is a colorless and highly irritating gas that forms when pollutants (including nitrogen oxides) emitted by cars, power plants, and other sources chemically react in the presence of sunlight. Ozone, the principal component of smog, is one of the most dangerous forms of air pollution in the United States today. Ozone in the air we breathe can be harmful to our health especially for sensitive groups with preexisting conditions (for example, asthma and chronic bronchitis), children and the elderly, and those who work outdoors. Low-income communities and communities of color disproportionately bear the burden of ozone pollution and the associated harms to health.

The regulation of ozone pollution also impacts the health of the Chesapeake Bay. Nitrogen oxides (NOx) emissions, an ozone precursor, also contribute to excess nitrogen pollution in the watershed, which leads to harmful algae blooms that keep sunlight from reaching underwater grasses and dead zones that lack enough oxygen to sustain fish, crabs, and other Bay species.

On December 31, 2020, EPA finalized a Rule that retained the existing NAAQS for ozone at the levels set in 2015 (70 ppb). This level is insufficient to protect public health and welfare as required by the CAA. Also, during the ozone review process, EPA repeatedly departed from long-established practice and disregarded scientific expertise, rendering the final Rule unlawful. On February 11, 2021, CBF joined a coalition of environmental and public health groups to file a challenge to the Rule in the D.C. Circuit. Our case was consolidated with other appeals. On February 22, 2021, the consolidated cases were held in abeyance as EPA reviews the 2020 Ozone NAAQS Rule in accordance with Executive Order 13990. 

In February 2022, EPA established a Clean Air Scientific Advisory Committee Review Panel. The Committee is an independent scientific review committee that provides scientific advice to EPA on matters related to the NAAQS. The Committee provided its final report to the EPA Administrator on June 9, 2023, concluding that the primary and secondary Ozone NAAQS should be revised.  The Advisory Committee identified several issues that warrant additional evaluation and review of the standards.  As a result, EPA chose to initiate a new statutory review of the ozone standards and on February 2, 2024, the case was remanded to EPA for further proceedings.  We will continue to monitor EPA’s review process. 

CBF is represented in this case by current Director of Litigation Ariel Solaski.