The national air quality standard for ground-level ozone, which was tightened slightly last year, may get ratcheted down again in 2010. EPA announced last week that it would reconsider the 0.075 ppm ozone standard set by the Bush Administration in 2008 (C&EN, March 17, 2008, page 12). That level is higher than the level recommended by the agency's Clean Air Scientific Advisory Committee, which said the standard should be between 0.06 and 0.07 ppm to protect millions of people who are susceptible to respiratory problems. But industry groups, including the American Chemistry Council, argued in the past that a previous limit of 0.08 ppm, which the 0.075 ppm standard replaced, is sufficient to protect health. EPA says it will review the scientific data used in the 2008 decision as well as the science advisers' recommendation. The agency said it will propose any revision to the standard by Dec. 21 and finalize any changes by Aug. 31, 2010.