The Environmental Protection Agency has lowered the National Ambient Air Quality Standard for ozone from 75 ppb to 70 ppb. Under the Clean Air Act, EPA is required to select a primary NAAQS for ground-level ozone that protects the nation’s public health within an “adequate margin of safety.” In March 2008, EPA lowered the primary NAAQS for ground-level ozone from 84 ppb to 75 ppb. Some health and green groups urged a limit as low as 60 ppb.
 
Farm Bureau supported retaining the 75 ppb standard.