Area Designations

This page last reviewed February 3, 2010

WHAT'S NEW

The 2010 State Area Designations Staff Report, also known as the Initial Statement of Reason (ISOR) has been released for public review. The Air Resources Board will consider any proposed changes to the State Area Designations at a Board Hearing on March 25, 2010 in Sacramento, California.

Information regarding the 2010 State Area Designations and the upcoming Board Hearing can be found at the links below:

Background:

The Air Resources Board has established health-based State ambient air quality standards to identify outdoor pollutant levels considered safe for the public. After State standards are established, State law required ARB to designate each area as attainment, nonattainment, nonattainment-transitional, or unclassified for each State standard. The area designations, which are based on the most recent available data, indicate the healthfulness of the air quality throughout the State. Further information can be found by viewing the State Standard Designations page.

In addition, the Federal Clean Air Act requires the U.S. Environmental Protection Agency (U.S. EPA) to set national ambient air quality standards. The national standard area designation maps and tables reflect these national primary standards. Further information regarding these standards and designations can be found by viewing the Federal Standard Designations page.

State and National Air Quality Standards (pdf)

We have established 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 to the mailing list by visiting the Area Designations List Serve Web Page and following the instructions there.

STATE STANDARD DESIGNATIONS

The Health and Safety Code (H&SC) section 39607(e) requires the Board to establish and periodically review area designation criteria. These designation criteria provide the basis for the Board to designate areas of California as attainment, nonattainment, or unclassified for the State standards.

In addition, H&SC section 39608 requires the Board to use the designation criteria to designate areas of California and to annually review those area designations. The Board makes area designations for ten pollutants: ozone, suspended particulate matter (PM10 and PM2.5), carbon monoxide, nitrogen dioxide, sulfur dioxide, sulfates, lead, hydrogen sulfide, and visibility reducing particles. Each year, the Board reviews the area designations and updates them as appropriate, based on the three most recent complete and validated calendar years of air quality data.

FEDERAL STANDARD DESIGNATIONS

The U.S. EPA designates areas for each pollutant for which there is a national ambient air quality standard. These area designations are included for your information; nonattainment area designations can be found on the U.S. EPA website.

EXCEPTIONAL EVENTS

Exceptional events are unusual or natural events that can overwhelm existing control strategies for man-made pollution. If such an event occurs and U.S. EPA agrees with the exceptional events determination, data that would have caused an exceedance of the NAAQS is not counted against an area's measure of air quality in relationship to compliance with air quality standards. Examples of exceptional events include (but are not limited to): wildfires, high winds and dust, volcanic activities, transported pollution, chemical spills and industrial accidents, terrorist attacks, structural fires, and fireworks.

Exceptional Events must meet five criteria before approval by either the State of California or U.S. EPA. These five criteria are:

1. Meets statutory definition of exceptional event,
2. Establishes a clear causal relationship between event and exceedance at air quality monitoring site,
3. Is beyond normal background and historical fluctuations,
4. Establishes that 'but-for' the event, the monitor at the site would not have exceeded the standard, and
5. Has met the public process and review procedures.

The public is provided with an opportunity to review and comment on the exceptional event documentation before it is submitted for final approval by the U.S. EPA. If you have any comments regarding the documents linked below, please contact Sylvia Zulawnick (szulawni@arb.ca.gov) or Theresa Najita (tnajita@arb.ca.gov) by the listed date.

2008 Northern California Wildfires - Submitted to U.S. EPA on August 28, 2009.

Contact Information

Comments and questions regarding this subject may be sent to:

Ms. Theresa Najita
Air Pollution Specialist
Air Quality Data Branch
Planning and Technical Support Division
California Air Resources Board
P.O. Box 2815
Sacramento CA 95812

(916) 322-7297

tnajita@arb.ca.gov

Data and Statistics