"A draft letter from a U.S. EPA science advisory committee recommends a tight standard for how much ozone pollution can be in the air, recommending that the lower bound of the standard should be 60 parts per billion, much lower than the current standard. But the letter notes that committee members haven't made a decision on the upper bound of the ozone standard.
To be sure, the letter has yet to be reviewed or approved by the overall committee, doesn't represent EPA policy and could change. But it's a sign that EPA may lower the current standard of 75 ppb, which could lead to both cleaner air for millions of Americans but also billions of dollars in extra costs for industry and added headaches for some states that already find it difficult to meet the current standard.
'The Second Draft [Policy Assessment] concludes that the scientific evidence and available information support consideration of a new primary ozone standard within the 60 ppb to 70 ppb range based on ozone as the indicator,' the 'consensus responses' part of the letter reads. 'The CASAC concurs that 60 ppb is an appropriate and justifiable scientifically based lower bound for a revised primary standard.'"