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EPA Says That It Plans To Retain Primary, Secondary Ozone National Ambient Air Quality Standards

July 13, 2020

by Paul Ciampoli
APPA News Director
Posted July 13, 2020

The Environmental Protection Agency (EPA) on July 13 announced a proposal to retain the primary and secondary ozone National Ambient Air Quality Standards (NAAQS).

The standards, established in 2015, are currently set at 70 parts per billion (ppb), in terms of a three-year average of the annual fourth-highest daily maximum 8-hour average ozone concentrations.

The Clean Air Act requires EPA to set national ambient air quality standards for “criteria pollutants.”

Currently, ozone and related photochemical oxidants, and five other major pollutants are listed as criteria pollutants. The others are carbon monoxide, lead, nitrogen oxides, particulate matter and sulfur oxides.

The Clean Air Act also requires EPA to periodically review, at least every five years, the relevant scientific information and the standards and revise them, if appropriate, to ensure that the standards provide the requisite protection for public health and welfare.

In the prior review of the ozone standards, which was completed in 2015, EPA increased the stringency of the levels of the ozone standards to 70 ppb from the 2008 standard of 75 ppb.

Emissions from sources such as cars, trucks, buses, industries, power plants, and products such as solvents and paints are among the major man-made sources of ozone-forming emissions.

According to the EPA, from 2017 to 2019, ozone concentrations fell four percent and since the beginning of the Trump Administration it has also re-designated 13 nonattainment areas for the 2008 eight-hour ozone standards to attainment.

EPA will accept comment on its proposed decision for 45 days after it is published in the Federal Register.

Additional information on the proposed decision is available here.