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 Benigno R. Fitial Governor Commonwealth ofthe Northern Mariana Islands Juan A. Sablan Memorial Building Capitol Hill Saipan, Marianas Protectorate 96950
Dear GovernorFitial:
On November 12,2010, I sent a letterproviding you the opportunity to recommend air quality designations for the revised primary National AmbientAir Quality Standard (NAAQS) for nitrogen dioxide (N02 ) for the Commonwealth ofthe Northern Mariana Islands. This letteris to notify you ofthe U.S. Environmental Protection Agency's (EPA) preliminary decision to designate all ofCNMI as unclassifiable/attainment and to inform you ofour approach 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 100parts perbillion (ppb). The EPA also retained the annual N02standard 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 occur more broadly across communities.
In ourNovember 2010 letter, the EPA stated that we anticipated designating most areas as "unclassifiable," indicating that there are insufficient data to determine whether ornot an area is attaining the revised N02NAAQS. The EPA believed this approach was appropriate given that: (1) the new near-road monitoring network requirements associated with the revised N02NAAQS will not be effective until January 2013, so air quality data from these new monitors would not be available to inform initial designations; and (2) the N02monitors in the existing N02network do not provide adequate evidence to determine whetherornot the new NAAQS 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 meet the 2010 N02NAAQS. While the EPA acknowledges that the existing N02 monitoring network does not provide adequate evidence to

Prinud on Recycled Papu

### determine whether ornot the new NAAQS is meteverywhere, there currently is no evidence of violations anywhere. Based on this, the EPA believes "unclassifiable/attainment" is the most appropriate designation to use at this time. The EPA intends to redesignate areas, as appropriate, after sufficient air quality data from the new monitoring network are available.
The EPA intends to designate CNMI as a single unclassifiable/attainment area. Alternatively, we will designate all areas ofCNMI as unclassifiable/attainment using any area boundaries you may provide in response to this letter. As we did in ourNovember 2010 letter, EPA recommends that each state and territory carefully consider the 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. Ifyou or your staffhave additional information that the EPA should considerwith respect to the designations including area boundary 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 after the notice oftheir availability is published in the Federal Register. We will review any information we receive from CNMI 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 together to implement the revised NOzNAAQS. Should you have any questions, please do nothesitate to call me, orhave your staffcontactDeborah Jordan ofmy staffat (415) 947-8715. Sincerely,

cc: FrankRabauliman Director, CNMI Division ofEnvironmental Quality