UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION IX 75 Hawthome Street San Francisco, CA 94105·3901

OFFICE OF THE REGIONAL ADMINISTRATOR 

## JUN 2 9 2011 The Honorable Edmund G. Brown, Jr Governor ofCalifornia State Capitol Building, Suite#1173 Sacramento, California 95814
Dear GovernorBrown:
I am writing to notify you ofthe U.S. Environmental Protection Agency's (EPA's) intention to designate all areas ofCalifornia as unclassifiable/attainment for the revised primary National Ambient Air Quality Standard (NAAQS) for nitrogen dioxide (NOz ) using the boundaries your State recommended in January 2011 or any revised boundaries that you submitin response to this letter. I am also writing to thank you for your State's previous recommendations, to provide you an opportunity to revise these previous recommendations for areaboundaries, and to inform you ofourapproach for completing the designations for the revised NOzNAAQS. OnJanuary 22,2010, the EPA strengthened the health-based NAAQS for NOzby setting a new I-hour NOzstandard at the level of 100parts perbillion (ppb). TheEPA also retained the annual NOzstandard of53 ppb. This suite ofstandards will protect public health by limiting people's exposures to short-term peak concentrations ofNOzand by limiting community-wide NOzconcentrations to levels below those that have been linked to respiratory-related emergency department visits and hospital admissions in the United States. Todetermine compliance with the new standard, the EPA established new ambient air monitoring and reporting requirements for NOzo In urban areas, monitors are required nearmajorroads as well as in other locations where maximum concentrations are expected. Additional monitors will be required in some large urban areas to measure the highest concentrations ofNOzthat occur more broadly across communities.
In ourNovember 2010 letter to Californiarequesting designation recommendations, the EPA stated that we anticipated designating most areas ofthe country as "unclassifiable," indicating that there are insufficient data to determine whether or not an area is attaining the revised NOzNAAQS. The EPA believed this approach was appropriate given that: (1) the new near-road monitoring network requirements associated with the revised NOzNAAQS will not be effective until January 2013, so air quality data from these new monitors would not be available to informinitial designations; and (2) the NOzmonitors in the existing NOznetwork do not provide adequate evidence to determine whether or not the new NAAQS is metat other locations, especially those closerto NOz emission sources such as roadways. After reviewing all the recommendations we received including California's, the EPA now intends to designate all areas ofthe country as "unclassifiable/attainment." The EPA is making this change because, based on the most recent airquality data from 2008-2010, all monitored areas in the country meet the 2010 NOzNAAQS. Whjle the EPA acknowledges that the existing NOz monitoring network

Printtd 0" Rt'cydl'd Papadoes notprovide adequate evidence to determine whether or not the new NAAQS is met everywhere, there currently is no evidence ofviolations anywhere in the country. Based on this, the EPA believes "unclassifiable/attainment" is the most appropriate designation to use at this time. TheEPA intends to redesignate areas, as appropriate, after sufficient air quality data from the new monitoring network are available. TheEPA intends to designate all areas ofCalifornia as unclassifiable/attainment using the boundaries your State recommended to the EPA in January 2011 or any revised boundaries you may provide in response to this letter. As we did in our November 2010 letter, EPA recommends that each state carefully considerthe implications ofthe boundaries it selects for its Prevention ofSignificant Deterioration permitting program for new or modified sources to ensure that they are consistent with its objectives for managing air quality deterioration and economic growth. Ifyour State has additional information that you want the EPA to consider with respect to the designations including any revisions to your State's recommended boundaries, please submitit to us by August 29,2011. We are also making the EPA's preliminary designation decisions and supporting documentation available to the general public for review. We are accepting public comments on our preliminary decisions for 30 days after the notice oftheir availability is published in the Federal Register. We will review any information we receive from the state ofCalifornia and the general public by these dates. We plan to promulgate the final designations by October 31, 2011. Thank you again for California's January 2011 recommendations for designations for the new I-hour N02 NAAQS. We look forward to a continued dialogue with you and your staffas we work together to implement this NAAQS. Should you have any questions, please do not hesitate to call me, orhave your staffcontactDeborahJordan ofmy staffat (415) 947-8715. Sincerely,

cc: Linda S. Adams Acting Secretary, CaliforniaEPA Mary Nichols Chairman, CARB
James Goldstene Executive Officer, CARB Lynn Terry DeputyExecutive Officer. CARB Kenneth Koyama Executive Director, CAPCOA