Calling a revised ozone rule “unworkable and overly burdensome,” the National Association of Manufacturers and the U.S. Chamber of Commerce challenged EPA’s revised ozone regulation in the U.S. Court of Appeals for the D.C. Circuit today.

NAM Senior Vice President and General Counsel Linda Kelly said the ozone rule could be “one of the most expensive in history” and would threaten the competitiveness of U.S. manufacturers.

In early October, EPA lowered the limit for ground-level ozone to 70 parts per billion (ppb) from a 75 ppb threshold set in 2008. Depending on their pollution levels, states have from 2020 to 2037 to comply with the revised rule.