The U.S. Environmental Protection Agency on July 13 announced its proposal to retain, without changes, the existing 2015 National Ambient Air Quality Standards for ozone. The current primary and secondary standards are set at 0.070 ppm, compared to an annual fourth-highest maximum eight-hour ozone concentration, averaged over three years. This proposal comes after careful review and consideration of the most current available scientific evidence and risk and exposure information, and with consultation of the Agency’s Clean Air Scientific Advisory Committee. The agency determined that the primary, health-based standard protects public health with an adequate margin of safety, including at-risk populations, and the secondary, welfare-based standard provides protection from an array of effects, including damage to vegetation.