Previous Federal Ozone Activities - 1997 Standard

This page last reviewed January 27, 2014


U.S. EPA revised the 1997 8-hour ozone standard in 2008, setting the 2008 8-hour ozone standard at a level of 0.075 ppm. Area designations and classifications for the 2008 standard were promulgated April 30, 2012. As part of this action, U.S. EPA revoked the transportation conformity provisions of the 1997 ozone standard, effective 1 year after designations for the 2008 standard are effective. "Transportation conformity” requires local transportation and air quality officials in nonattainment areas to coordinate planning to ensure that transportation-related emissions from projects, such as road construction, do not interfere with an area’s ability to reach its clean air goals. 

Past Activities -- 1997 Federal 8-Hour Ozone Standard (0.08 ppm):

In November 2002, U.S. EPA entered into a Consent Decree with several environmental groups over U.S. EPA's failure to designate 8-hour ozone nonattainment areas by the July 2000 mandated deadline. Under the terms of the Consent Decree, U.S. EPA was to promulgate 8-hour ozone designations no later than April 2004.

To support U.S. EPA's action, ARB provided U.S. EPA with California's recommendations for 8-hour ozone area designations on July 15, 2003. The recommendations and supporting data were an update to a report submitted to U.S. EPA in July 2000. On December 3, 2003, U.S. EPA published its proposed designations. U.S. EPA's proposal differed from the State's recommendations primarily on the appropriate boundaries for several nonattainment areas. ARB responded to U.S. EPA's proposal on February 4, 2004.

2004 Transmittal to U.S. EPA:

2003 Letter from U.S. EPA to Governor Schwarzenegger on State's Recommendations for the 1997 Federal 8-Hour Ozone Standard   (PDF -- 2.5 MB)

2003 Transmittal to U.S. EPA:


The U.S. EPA established the 8-hour ozone standard in July 1997. On May 13, 1999, the ARB conducted a public workshop on draft area designation recommendations for the 1997 8-hour ozone standard. On May 14, 1999, the U.S. Court of Appeals for the District of Columbia put a hold on implementation of the 1997 8-hour ozone standard. As a result of the Court decision, U.S. EPA opted to ask states to submit only a list of monitors that violate the standard. ARB transmitted California's list to U.S. EPA on August 12, 1999.

Although the Court of Appeals prohibited U.S. EPA from implementing the 1997 8-hour ozone standard, it did note that the Clean Air Act requires U.S. EPA to finalize area designations within specific timeframes. On March 23, 2000, the Board approved staff's recommendations for area designations. ARB transmitted California's area designations recommendations to U.S. EPA, including the most current air quality monitoring data, on July 14, 2000.

On February 27, 2001, the U.S. Supreme Court unanimously upheld U.S. EPA's authority to set the 1997 8-hour standard.

2000 Transmittal to U.S. EPA:

2000 Board Meeting Materials:

1999 Transmittal to U.S. EPA:




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