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

OFFICE OF THE REGIONAL ADMINISTRATOR 

## JUN 2 9 2011 The Honorable Eddie Baza Calvo Governor Ten-itory ofGuam Ricardo 1. Bordallo Governor's Complex Adelup, Guam 96910 Dear Governor Calvo: OnNovember 12,2010, I sent a letter providing your Tenitory the opportunity to recommend air quality designations for the revised primaryNational Ambient Air Quality Standard (NAAQS) for nitrogen dioxide (N02) for Guam. This letter is to notify you ofthe U.S. Environmental Protection Agency's (EPA) preliminary decision to designate all ofGuam as unclassifiable/attainment and to inform you of ourapproach for completing the designations for the revised N02standard. On January 22,2010, the EPA strengthened the health-based NAAQS for N02by setting a new I-hour N02standard at the level of 100 parts per billion (ppb). The EPA also retained the annual N02 standard of53 ppb. This suite ofstandards will protect public health by limiting people's exposures to short-term peak concentrations ofN02and by limiting community-wide N02concentrations to levels·below those that have been linked to respiratory-related emergency department visits and hospital admissions in the United States. To determine compliance with the new standard, the EPA established new ambient air monitoring and reporting requirements for N02. In urban areas, monitors are required near major roads 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 ofN02that occurmore broadly across communities. In ourNovember 2010 letter, the EPA stated that we anticipated designatingmost areas as "unclassifiable," indicating that there are insufficient datato determine whether or not an area is attaining the revised N02NAAQS. The EPA believed this approach was appropriate given that: 

### (l) the new near-road monitoring network requirements associated with the revised O2NAAQS will not be effective until January 2013, so air quality datafrom these new monitors would not b available to inform initial designations; and (2) the N02monitors in the existing N02network do not provide adequate evidence to determine whether ornotthe newNAAQS is met at other locations, especially those closer to N02emission sources such as roadways. After reviewing all the recommendations we received, the EPA now intends to designate all areas as "unclassifiable/attainment." The EPA is making this change because, based on the most recent air quality data from 2008-2010, all monitored areas meetthe 2010 N02NAAQS. While the EPA acknowledges that the existingN02 monitoring network does notprovide adequate evidence to determine whether or not the newNAAQS is met everywhere, there currently is no evidence of violations anywhere. Based on this, the EPAbelieves "unclassifiable/attainment" is the most appropriate

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### designation to use at this time. The EPA intends to redesignate areas, as appropriate, after sufficient air quality data from the newmonitoring network are available. The EPA intends to designate Guam as a single unclassifiable/attainment area. Alternatively, we will designate all areas ofGuam as unclassifiable/attainment using any area boundaries you may provide in response to this letter. As we did in our November 

### 2010 letter, EPA recommends that each state and territory carefully considerthe implications ofthe boundaries it selects for its Prevention ofSignificant Deterioration permitting program for new ormodified sources to ensure that they are consistent with its objectives for managing air quality deterioration and economic growth. Ifyou or your staffhave additional information that the EPA should consider 

### with respect to the designations including areaboundary recommendations, please submit it 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 ourpreliminary decisions for 

### 30 days afterthe notice oftheir availability is published in the Federal Register. We will review any information we receive from Guam and the general public by these dates. We plan to promulgate the final designations by October 

### 31,2011. We look forward to a continued dialogue with you and your staffas we work togetherto implement the revised N02 

### NAAQS. Should you have any questions, please do not hesitate to call me, orhave your staffcontact Deborah Jordan ofmy staffat 

### (415) 947-8713. Sincerely,

cc: Ivan Quinata Administrator, Guam EPA Peter Cruz AirPollution Control Program Manager, Guam EPA