The EPA is proposing to strengthen the nation’s air quality standards for ground-level ozone, revising the standards for the first time since 1997. 

The proposal recommends an ozone standard within a range of 0.070 to 0.075 parts per million. EPA also is taking comments on alternative standards within a range from 0.060 ppm up to the level of the current 8-hour ozone standard, which is 0.08 ppm.

EPA also is proposing to revise the “secondary” standard for ozone to improve protection for plants, trees and crops during the growing season.

The agency will take public comment for 90 days following publication of the proposal in the Federal Register and will hold four public hearings. The hearings will be held in Los Angeles and Philadelphia on Aug. 30, and in Chicago and Houston on Sept. 5.