Honorable John A. Hughes, Secretary 

Delaware Department of Natural Resources 

and Environmental Control 

89 Kings Highway 

Dover, Delaware 19901 

Dear Secretary Hughes: 

On March 12,2008, the U.S. Environmental Protection Agency (EPA) revised the 

national ambient air quality standards (NAAQS) for ozone to provide increased protection of 

public 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 many of the health effects associated with ozone 

exposure have been demonstrated at and below the level of the 0.08 ppm standard, which was 

promulgated in 1997. These include a range of serious 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 one year of promulgation of a new or revised NAAQS, section 107(d)(l)(A) of 

the Clean Air Act requires the Governor of each state to submit to EPA a list of all areas in the 

state, recommending designations for each as "attainment," "nonattainment," or "unclassifiable" 

with respect to the new or revised standard. Therefore, EPA asks that you provide your 

designation recommendations, including appropriate area boundaries, to EPA by March 12,2009 

with respect to the revised ozone NAAQS. Establishing area designations is a key step in the 

process of providing the health protections that the Clean Air Act mandates. Areas that are 

designated as not attaining the air quality standards will be required to adopt plans to reduce 

ambient concentrations of ozone. 

The enclosed memorandum provides guidance to state and local air pollution control 

agencies and Tribes on the process for designating areas under the 2008 revised ozone standard. 

EPA plans to announce our intended designations as early as possible after receipt of your 

recommendations, but no later than 120 days prior to promulgating final designations. 

Following the announcement of intended designations, states and Tribes will have the 

opportunity to comment on any modifications EPA proposes to their recommendations. In 

accordance with section 107(d)(l)(B) of the Clean Air Act, we intend to issue final designations 

by March 12,201 0 (although that deadline may be extended up to one additional year if EPA 

determines that insufficient information is available to establish designations by that date). Our 

designations will be based on the most recent three years of certified, quality assured monitoring 

data available. Ozone nonattainment areas will be classified at the time of designation. 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. 
Donald S. Welsh Regional Administrator 

Enclosure 

cc: Mr. Ali Mirzakhalili, Program Administrator 

Air Quality Management Section 

Delaware Department of Natural Resources and Environmental Control