What Does .0075 Parts Per Billion Mean?

A hearing on ozone standards can be very abstract for non-scientists. So credit goes to Rep. Brian Higgins (D-N.Y.) for laying out before EPA Administrator Stephen Johnson what it means to set an ozone standard at .0075 parts-per-billion instead of .0060 parts-per-billion, which Johnson’s scientific staff recommended.

"500 premature deaths…1,400 non-fatal heart attacks…10,000 asthma attacks," Higgins said to Johnson. He was getting these estimates from EPA’s science staff report.

Johnson’s response- The Clean Air Act does not require a problem-free safety standard.