EPA reverses decision to delay 2015 ozone rule

Number of counties regulated by ozone air quality standards is expected to increase under 2015 rule

The Environmental Protection Agency will no longer delay implementation of the 2015 National Ambient Air Quality Standards for ground-level ozone.

EPA’s recent announcement reverses its decision in June to delay the rule until October 2018. The ozone rule, which was finalized in 2015, would tighten the current ozone standard of 75 parts per billion, last set in 2008, to 70 parts per billion.

Since December 2015, the EPA has been working with state governments to determine which counties violate the 70 parts per billion standard. With the recent decision not to delay, the agency is expected to make final nonattainment designations for the 2015 ozone standard by October. Once nonattainment areas are announced, states — and in some cases, local agencies and tribes — will be required to develop and submit an ozone implementation plan to address the pollution levels.

Ground-level ozone is one of the six air pollutants regulated by the Clean Air Act National Ambient Air Quality Standards (NAAQS) program. Under the program, the EPA is required to reassess air quality standards every five years. Primarily known as a summertime pollutant, ozone forms when sunlight reacts with pollutants such as volatile organic compounds emitted from chemical plants, gasoline pumps, oil-based paints and auto body and print shops. Sources of nitrogen oxides include power plants, industrial facilities and motor vehicles.

Under the Clean Air Act, states and counties serve as co-regulators with the federal government and are ultimately responsible for the implementation of new and existing air quality standards.

A more stringent ozone standard could have an effect on counties nationwide.

Ozone designations can have a significant impact on county governments since counties are both the regulator and regulated entity of Clean Air Act programs.

Currently, 227 counties, primarily urban and in the East, are regulated under ozone air quality standards. Under the new 70 parts per billion standard, that number is expected to increase.

Nonattainment designations will create challenges for counties’ ability to update and improve their transportation systems, and attract and retain businesses as they are required to impose tighter regulations on local businesses and other pollution sources in order to meet the standards.