EPA Staff Policy Assessment Recommends Reduction in Ozone Standard from 75 ppb to 60-70 ppb

The staff of the US Environmental Protection Agency’s (EPA) Office of Air Quality Planning and Standards (OAQPS) has released the final version of the policy assessment (PA) for the review of the ozone (O3) National Ambient Air Quality Standards (NAAQS).

Among the staff recommendations are to further reduce the primary ozone standard from the current 75 ppb (parts per billion) to a revised level within the range of 70 ppb to 60 ppb—and preferably below 70 ppb.

Ozone acts as a greenhouse gas, absorbing some of the infrared energy emitted by the earth. Quantifying the greenhouse gas potency of ozone is difficult because it is not present in uniform concentrations across the globe.  However, the most widely accepted scientific assessments relating to climate change (e.g., the Intergovernmental Panel on Climate Change Third Assessment Report) suggest that the radiative forcing of tropospheric ozone is about 25% that of carbon dioxide.

EPA Staff Policy Assessment Recommends Reduction in Ozone Standard from 75 ppb to 60-70 ppb