1997 8-Hour Ozone Standard

In 1997, the Environmental Protection Agency (EPA) revised the 1-Hour ozone standard from 0.12 parts per million (ppm) averaged over one hour to an 8-Hour average standard of 0.08 ppm.  Non-attainment designations are classified as marginal, serious, severe, or extreme depending on the magnitude of the highest 8-Hour ozone design value at a monitoring site in a non-attainment area.  The design value for the 8-Hour ozone standard is defined as the 4th highest daily maximum concentration averaged over 3 years.  Based on 2001-2003 monitoring data, the 8-Hour ozone design value was identified as 0.107 ppm at the Cool monitoring site.  EPA designated Sacramento and Yolo counties and portions of El Dorado, Placer, Solano and Sutter counties as a serious non-attainment area for the 8-Hour ozone standard in 2004.  This non-attainment area is referred to as the Sacramento Federal Non-attainment Area (SFNA).  The SFNA was assigned an attainment date of June 15, 2013.

Bump Up Request

The SFNA is dependent on state and federal emission reduction programs to achieve attainment.  These state and federal strategies however, are more long term in nature and the SFNA’s reliance on these programs does not allow for attainment by the 2013 deadline.  The SFNA submitted a request to EPA in February 2008 for a voluntary bump-up to a higher classification to allow more time for state and federal programs to be implemented and for the region to attain the standard.  The bump-up request extended the attainment deadline to June 15, 2019.  EPA issued a final rule approving the area’s bump-up request from serious to severe non-attainment on May 5, 2010.

8-Hour Ozone Attainment and Reasonable Further Progress Plan

Specific planning requirements are outlined in the Clean Air Act depending on an area’s non-attainment classification.  One of those planning requirements is an area’s responsibility to develop an attainment plan which demonstrates how it will meet the ambient air quality standard by a certain date.  Districts in the SFNA developed the Sacramento Regional 8-Hour Ozone Attainment and Reasonable Further Progress Plan to fulfill this planning requirement and demonstrate how the area will meet its attainment deadline in June 2019 for the 1997 8-Hour ozone standard.