There is one federal primary standard for ozone - an 8-hour average standard of 0.070 parts per million (ppm); the secondary standard is the same as the primary. Detailed information about activities related to the federal ozone standards and designations can be found on the U.S. EPA website. Maps of current area designations can be found through the Resources tab on the left.
Information about specific nonattainment areas and the efforts to bring them into attainment of the federal standards can be found on the California State Implementation Plan webpage.
2015 0.070 ppm 8-Hour Ozone Standard
- July 2018 - U.S. EPA finalized area designations
- October 2016- CARB submits recommended area designations to U.S. EPA
- October 2015 - U.S. EPA lowered the federal 8-hour primary and secondary ozone standard from 0.075 ppm to 0.070 ppm
More information on the 2015 standard, including a number of fact sheets and the U.S. EPA implementation memo, can be found on the U.S. EPA Ground-Level Ozone 2015 NAAQS Regulatory Actions website.
2008 0.075 ppm 8-Hour Ozone Standard
- April 2012 - U.S. EPA issued final area designations and classifications.
- The designations included two new nonattainment areas -- Eastern San Luis Obispo County and the Tuscan Buttes area of Tehama County (Federal Register (FR) Notice for area designations published May 21, 2012; FR Notice May 21, 2012; effective July 20, 2012).
- March 2009 - CARB submits recommended area designations to U.S. EPA
- Letter of submittal to U.S. EPA
- Enclosure 1: Summary of recommended area designations
- Enclosure 2: Revised staff report and attachments
- Enclosure 3: Supporting information for recommended nonattainment areas
- Enclosure 4: Nonattainment area boundary descriptions
- Enclosure 5: Ozone air quality summary data by site
- March 2008 - U.S. EPA revised the 8-hour ozone standard (FR Notice March 27, 2008; effective May 27, 2008).
More information on the 2008 standard, including a number of fact sheets and the U.S. EPA implementation memo, can be found on the U.S. EPA Ground-Level Ozone 2008 NAAQS Regulatory Actions website. Information on current area designation status for this standard can be found on the U.S. EPA Green Book 8-Hour Ozone (2008) Area Information webpage.
1997 0.08 ppm 8-Hour Ozone Standard
The 1997 standard was revoked in April 2015.
- December 2012 - U.S. EPA determined the following seven (7) areas had attained the 1997 federal 8-hour ozone standard (FR Notice December 3, 2012; effective January 2, 2013):
- Amador and Calaveras Counties (Central Mountain Counties)
- Chico (Butte County)
- Eastern Kern County (Mojave Desert Air Basin portion of County)
- Mariposa and Tuolumne Counties (Southern Mountain Counties)
- Western Nevada County
- Sutter County (Sutter Buttes), and
- Ventura County (excluding the Channel Islands -- Anacapa and San Nicolas islands)
- April 2012 - U.S. EPA reclassified Subpart 1 areas under the 1997 8-hour ozone standard (FR Notice May 14, 2012; effective June 13, 2012).
- June 2004 - EPA issued final nonattainment area designations.
- February 2004 - CARB submitted updated recommended area designations
- Letter of submittal to U.S. EPA
- Appendix: Additional information to support U.S. EPA's reconsideration of proposed area boundaries and designations
- Enclosure 1: Updated recommendations for area designations based on 2001-2003 data
- Enclosure 2: Boundary descriptions for recommended nonattainment areas
- Enclosure 3: Cover only of correspondence from local officials on area designations
- July 2003 - CARB updated recommended area designations to U.S. EPA.
- July 2000 - CARB submitted recommended area designations to U.S. EPA.
Information on current area designation status for this standard can be found on the U.S. EPA Green Book 8-Hour Ozone (1997) Area Information webpage.