Under the Clean Air Act, EPA is required to carry out a periodic review and revision, as appropriate, of the air quality criteria and the primary and secondary standards for six criteria air pollutants, which include ozone. Primary standards set limits to protect public health, including the health of "sensitive" populations such as asthmatics, children, and the elderly. Secondary standards set limits to protect public welfare, including protection against decreased visibility, damage to animals, crops, vegetation, and buildings.
EPA’s Office of Air and Radiation has requested CASAC review of its draft "Policy Assessment for the Review of the Ozone National Ambient Air Quality Standards – Second External Review Draft." The purpose of the Policy Assessment is to “bridge the gap” between the scientific information and the judgments required of the Administrator in determining whether it is appropriate to retain or revise the ozone standards. The CASAC previously reviewed the first external review draft of the Agency's Policy Assessment.