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 of Guam 

Ricardo 1. Bordallo Governor's Complex 

Adelup, Guam 96910 

Dear Governor Calvo: 

On November 12,2010, I sent a letter providing your Tenitory the opportunity to recommend air quality 

designations for the revised primary National Ambient Air Quality Standard (NAAQS) for nitrogen 

dioxide (N02) for Guam. This letter is to notify you of the U.S. Environmental Protection Agency's 

(EPA) preliminary decision to designate all of Guam as unclassifiable/attainment and to inform you of 

our approach for completing the designations for the revised N02 standard. 

On January 22,2010, the EPA strengthened the health-based NAAQS for N02 by setting a new I-hour 

N02 standard at the level of 100 parts per billion (ppb). The EPA also retained the annual N02 standard 

of 53 ppb. This suite of standards will protect public health by limiting people's exposures to short-term 

peak concentrations ofN02 and by limiting community-wide N02 concentrations 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 ofN02 that occur more 

broadly across communities. 

In our November 2010 letter, the EPA stated that we anticipated designating most areas as 

"unclassifiable," indicating that there are insufficient data to determine whether or not an area is 

attaining the revised N02 NAAQS. 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 data from these new monitors would not b available to 

inform initial designations; and (2) the N02 monitors in the existing N02network do not provide 

adequate evidence to determine whether or not the new NAAQS is met at other locations, especially 

those closer to N02 emission 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 N02 NAAQS. While the EPA 

acknowledges that the existing N02 monitoring network does not provide adequate evidence to 

determine whether or not the new NAAQS is met everywhere, there currently is no evidence of 

violations anywhere. Based on this, the EPA believes "unclassifiable/attainment" is the most appropriate 

Printed on Recycled Papu 
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 Guam as a single unclassifiable/attainment area. Alternatively, we will 

designate all areas of Guam 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 consider the implications of the boundaries it selects for its Prevention of Significant 

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. 

If you or your staff have additional information that the EPA should consider with 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 our preliminary decisions for 30 

days after the notice of their 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 staff as we work together to implement the 

revised N02 NAAQS. Should you have any questions, please do not hesitate to call me, or have your 

staff contact Deborah Jordan of my staff at (415) 947-8713. 

Sincerely, 

cc:	 Ivan Quinata 

Administrator, Guam EPA 

Peter Cruz 

Air Pollution Control Program Manager, Guam EPA