Linn County Air Quality Division
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EPA proposes to revise the ozone standard

December 01, 2014

On November 26, 2014, the U.S. Environmental Protection Agency (EPA) announced its proposal to strengthen the National Ambient Air Quality Standards (NAAQS) for ground-level ozone. EPA proposes to strengthen the standard to within a range of 65 to 70 parts per billion (ppb), while taking comments on a level as low as 60 ppb. A 90-day public comment period will open once the proposal is published in the Federal Register, probably in the next two to three weeks.

A court ordered schedule requires the final rule be signed by October 1, 2015. State-submitted designation recommendations will be due one year later and EPA’s final designations are expected by October of 2017, likely based on 2014-2016 ambient air quality data. More information on EPA’s proposal is available on their website at

Basic information on ozone pollution can be found on the DNR’s website at and the most recent ozone design values in Iowa are provided at