An EPA advisory board is formally urging the agency to tighten its national air quality standard for ozone, saying the current standard of 75 ppb is too high to protect people from developing asthma and other health problems. In a letter to EPA Administrator Gina McCarthy, the Clean Air Scientific Advisory Committee says there is “adequate scientific evidence” to recommend that the agency consider a standard between 60 and 70 ppb. The advisory committee notes that a standard lower than 70 ppb is preferable because there is substantial evidence of adverse health effects at that level. “Although a level of 70 ppb is more protective of public health than the current standard, it may not meet the statutory requirement to protect public health with an adequate margin of safety,” the committee says. Industry groups say lowering the current threshold could result in costly new emissions controls. EPA is under court order to propose a new ozone standard by Dec. 1 and finalize it by October 2015.