Chemical manufacturers and congressional Republicans are opposing EPA’s late-November proposal to tighten the national limit for ground-level ozone—a major component of smog—predicting the move would harm the economy. The American Chemistry Council, a manufacturers’ association, says that, if implemented, the tighter standard could hurt the U.S. chemical industry’s planned expansion. Under its Clean Air Act proposal, EPA would make the current federal air quality standard for ozone more protective of health by setting it somewhere in the range of 65 to 70 parts per billion. The current standard, set in 2008, is 75 ppb. Environmental and health groups welcomed the plan, but some are concerned that EPA’s formal proposal does not include the 60-ppb level recommended by the agency’s panel of independent science advisers. However, the proposal seeks comments from the public about a possible 60-ppb standard. EPA is under a federal court order to finalize a new standard by Oct. 1, 2015. The incoming Republican-controlled Congress likely will attempt to thwart EPA from adopting a tighter standard.