UNITED STATES ENVIRONMENTAL PROTECTION AGENCY REGION 10 1200 Sixth Avenue. Suite 900**S~attle.** WA 98101-3140 

### JAN 9 2009 REGIONAl ADMINISTRATOR



### CERTIFIED MAIL

- RETURN RECEIPT REQUESTED

The Honorable C. L. "Butch" Otter Governor ofIdaho Post Office Box 83720 Boise, Idaho 83720

Dear Governor Otter:

On March 12, 2008 the Environmental Protection Agencyrevised the national ambient 

### air quality standards (NAAQS) for ozone to provide increased protection ofpublic health and welfare from ozone pollution. The new primary ozone standard was lowered from 0.08 parts per million (ppm) to 0.075 ppm based on numerous epidemiological studies conducted during the past decade in which manybfthehealth effects associated with ozone exposure have been demonstrated at and below the level ofthe 0.08 ppm standard, which was promulgated in 1997. These include a range ofserious respiratory effects and increased premature mortality. EPA also strengthened the secondary 8-hour ozone standard, making it identical 

### to the revised primary standard, to protect against welfare 

### effects such as impacts on vegetation and forested ecosystems.

. . Within oneyear ofpromulgation ofa new orrevised NAAQS, section 1 07(d)(1)(A) of the Clean Air Actrequires the Governor ofeach state to submit 

### to EPA a list ofall areas in the state, recommending designations for each as "attainment," ''nonattainment,'' or "unclassifiable" with respect to the new orrevised standard. Therefore, we ask that youprovide your designation recommendations, including appropriate areaboundaries, to EPA byMarch 12, 2009, with respect to therevised ozoneNAAQS. Establishing area designations is a key step in the process ofproviding the health protections that the Clean AirAct mandates. Areas that are designated as not attaining the airquality standards will berequired to adopt plans to reduce ambient concentrations ofozone.

The enclosed memorandum provides guidance to state and local air pollution control agencies and Tribes on theprocess for designating areas under the 2008 revised ozone standard. We plan to announce our intended designations as early as possible afterreceipt ofyour recommendations, but no later than 120 days priorto promulgating final designations. Following the announcement ofintended designations, states and Tribes will have the opportunityto coniment on anymodifications EPA proposes to theirrecommendations. 

### In

. accordance with section 107(d)(1)(B) ofthe Clean AirAct, we intend to issue final designations byMarch 12,2010 (although that deadline may be extended up to one additional year ifEPA detennines that insufficient information is available to establish designations by that date).

### Our designations will be based on the most recent 3 years ofcertified, quality assured monitoring data available. Ozone nonattainment areas will be classified at the time ofdesignation. The approach EPA will use to classify nonattainment areas under the 2008 revised ozone NAAQS 

### will be established through a separate notice-and-comment rulemaking. 

# We look forward to working with you and your staffto develop area designations under the 2008 revised ozone standards in a timely manner. Ifyou have any questions, please do not hesitate to contact me. Your air 

### quality staffmay wish to contact State and Tribal Air

### Program Manager, Mahbubul Islam at (206) 553-6985 or Krishna Viswanathan at (206) 553-2684.
Sincerely,

# 'i~ Elin D. Miller Regional Administrator

. Enclosure



### 00: Ms. Toni**~ardesty** 

### Director, Idaho Department

ofEnvironmental Quality

Mr. Martin Bauer Administrator, Division ofAir Quality Idaho Department ofEnvironmental Quality