Air Quality Standards and Area Designations
This page reviewed May 5, 2016
WHAT'S NEWOn October 1, 2015, the U.S. EPA lowered the federal 8-hour primary and secondary ozone standard. U.S. EPA will promulgate designations for this more stringent standard by October 1, 2017. Further information can be found on ARB's Federal Standard Designations webpage.
State Standard Area Designations page.
In addition to State standards, the Federal Clean Air Act requires the United States Environmental Protection Agency (U.S. EPA) to set national ambient air quality standards (federal standards, national standards, or NAAQS). The federal area designation maps and tables reflect these federal standards. Further information about the federal standards and area designations can be found on the Federal Standard Area Designations page.
We maintain an e-mail mailing list for Area Designation activities. As announcements, reports, and other information are posted to this website, we will send e-mail notifications to everyone on the list. If you wish to receive these notices, you can subscribe by visiting the Area Designations List Serve web page and following the instructions there.
U.S. EPA website.
- Current Federal Area Designation Activities
- Federal Area Designation Maps
- Prior Federal Designation Activities (2008 ozone standard)
- Prior Federal Designation Activities (1997 ozone standard)
wildfires, high winds and dust, volcanic activities, stratoshperic ozone intrusion, structural fires, and fireworks.
Exceptional Events must meet the following five criteria before being approved by either the State or U.S. EPA:
- The event must meet the statutory definition of an exceptional event,
- There must be a clear causal relationship between the event and the measured exceedance,
- The concentration must be higher than normal background and historical fluctuations,
- It must be established that the measured concentration would not have exceeded the standard, "but-for" the event, and
- The State must satisfy public process and review procedures.
ARB provides an opportunity for public review and comment on the exceptional events documentation before submitting it to U.S. EPA for final approval.
- 2007 Southern California High Winds and Wildfires (PM2.5 and PM10) - COMMENT PERIOD CLOSED; Submitted to U.S. EPA on April 20, 2010.
- 2008 Northern California Wildfires (PM2.5 and PM10) - COMMENT PERIOD CLOSED; Submitted to U.S. EPA on August 28, 2009; U.S. EPA partial concurrence (March 22, 2010, and April 2, 2010).
- 2008 Northern California Wildfires (1-Hour Ozone -- Sacramento Metro Area) - COMMENT PERIOD CLOSED; Submitted to U.S. EPA on March 30, 2011; U.S. EPA concurrence April 13, 2011.