AIR POLLUTION: EPA science advisers endorse tighter ozone standard Amanda Peterka, E&E reporter Published: Friday, June 27, 2014 U.S. EPA science advisers have officially endorsed a tighter ozone standard in the range of 60 to 70 parts per billion. Please subscribe to Greenwire to read the full story. Username: Password: Forgot your access codes? Recover them. Not a subscriber? Sign up for a trial. Ready to subscribe? Click here.