The U.S. Environmental Protection Agency strengthened National Ambient Air Quality Standards (NAAQS) for the ground-level ozone on Oct 1, 2015. Specific changes include EPA revising the 8-hour ozone standards (public health) and secondary standards (public welfare) to 70 parts per billion (ppb). This is down from 75 parts per billion (ppb). The federal standard of 70 parts per billion for 8 hours of ozone became operative on Dec 28, 2015.

Public health is protected by primary standards, which include protecting vulnerable populations such as asthmatics, children, and the elderly. Public welfare standards protect animals, vegetation, crops, and buildings, including preventing reduced visibility.

Environmental Protection Agency On Ground Level Ozone

A “reasonable margin of safety” applies to air quality standards set by the EPA. This includes protecting the health of at-risk groups as well. Administrator of this standard takes into consideration factors such as the level of certainty or uncertainty of the research into ozone-related effects, the nature and severity of those effects, and the size of the at-risk groups as part of the evaluation process. Under the law, the Administrator is tasked with setting “requisite” standards, meaning no standards should be more or less stringent than needed to achieve these goals.

A panel of scientists appointed by the EPA, the Clean Air Scientific Advisory Committee (CASAC), determined that a standard of 70 parts per billion to 60 parts per billion would be adequate to protect public health in 2008, while a standard of 75 parts per billion would still be too high.

EPA Administrator concluded that the 2015 standard of 70 ppb is adequate to protect public health with a conservative margin of safety, as required by law, on the basis of an expanded body of scientific evidence that includes various studies on the effects of ozone on health.

In this act, EPA revised the air quality index for ozone to reflect the revised, more stringent standards as well as strengthening the NAAQS for ozone. An AQI chart provides information about air pollution levels in communities based on color coded values.

Air Quality Index (AQI) Breakpoints for the 2008 and 2015 Federal 8-Hr Ozone Standards:

Also Read: Ozone And Biocidal Product Regulations For EU Countries