WASHINGTON, D.C. — The U.S. Environmental Protection Agency (EPA) moved to strengthen air-quality standards earlier this month to cut levels of ground-level ozone (O3), or smog. The new rule establishes a new limit of 75 ppb, down from 85 ppb.
Though the new rule shaves just 10 ppb from the old standard, it will quadruple the number of counties exceeding mandated limits. Groups representing children and the elderly had pressed for an even lower limit of 60 ppb.
