Dive Brief:

• The U.S. Environmental Protection Agency has concluded that 85% of counties in the United States are in compliance with the 2015 National Ambient Air Quality Standards (NAAQS) for ozone, including 2,646 counties, Indian Country located in those counties, two separate areas of Indian Country and five territories.
• Officials had intended to delay the findings, but over the summer withdrew a one-year hold on the Obama-era standards for ground-level ozone after 15 states and the District of Columbia filed a lawsuit.
• EPA plans to address areas not designated in compliance in the future.

Dive Insight:

EPA has held off on determining what parts of the country are out of compliance with its ozone standards, and has indicated those would be addressed in a future action. The vast majority of counties were designated as Attainment/Unclassifiable.

The designations are based on a new, stricter 70-parts per billion (ppb) ozone standard, lowered from 75 ppb. States out of compliance would need to take steps to lower ozone levels in the affected areas, which could mean tighter controls on industrial and other sources of air pollution.

"These are counties with one or more monitors attaining the 2015 ozone NAAQS or counties for which the EPA does not have reason to believe are violating the 2015 ozone NAAQS or are contributing to a violation of the 2015 ozone NAAQS in another county," EPA said in a final rule published in today's Federal Register.

EPA also designated three counties in the state of Washington as “unclassifiable," due to a lack of data to calculate a 3-year ozone design value. For the remaining areas, EPA said it is is not extending the time provided under the Clean Air Act, but also is "not yet prepared to issue designations. The agency intends to address these areas in a separate future action."

Over the summer, the Trump administration announced it would delay implementation of stricter ozone standards, following an April decision from the D.C. Circuit Court of Appeals to stay previous litigation on the rule. But the agency reversed course when states sued in June to stop the delay.