The Honorable Vincent C. Gray

Mayor ofthe District of Columbia

1350 Pennsylvania Avenue, N.W.

Suite 316

Washington, D.C. 20004

Dear Mayor Gray:

Thank you for your March 11, 2009 recommendations on air quality designations for the

revised 2008 National Ambient Air Quality Standards (NAAQS) for ozone throughout the District of

Columbia. I appreciate the information the District of Columbia shared with the U.S. Environmental

Protection Agency (EPA) as we move forward to improve ozone air quality. This letter is to notify

you ofEPA’s preliminary response to the District of Columbia’s recommendations and to inform youof our approach for completing the designations for the revised ozone standards.

On March 12, 2008, EPA revised its NAAQS for ground-level ozone to provide increased

protection of public health and the environment. EPA lowered the primary 8-hour ozone standard

from 0.08 parts per million (ppm) to 0.075 ppm to protect against health effects associated with ozoneexposure, including a range ofserious respiratory illnesses and increased premature death from heart

or lung disease. EPA revised the secondary 8-hour ozone standard, making it identical to the primary

standard, to protect against welfare effects, including impacts on sensitive vegetation and forested

ecosystems.

History shows us that better health and cleaner air go hand-in-hand with economic growth.

Working closely with the states and tribes, EPA is implementing the standards using a common sense

approach that improves air quality and minimizes the burden on state and local govermnents. As part

ofthis routine process, EPA is working with the states to identif’ areas in the country that meet the

standards and those that need to take steps to reduce ozone pollution. Within one year after a new or

revised air quality standard is established, the Clean Air Act (CAA) requires the Governor of each stateto submit to EPA a list of all areas in the state, with recommendations for whether each area meets thestandard. As a first step in implementing the 2008 ozone standards, EPA asked states to submit their

designation recommendations, including appropriate area boundaries, by March 12, 2009. InSeptember 2009, EPA announced it was reconsidering the 2008 ozone standards. EPA later took steps

to delay the designation process for the 2008 ozone standards pending outcome ofthe reconsideration.However, in September 2011, the Office of Management and Budget returned to EPA the draft finalrule addressing the reconsideration ofthe 2008 ozone standards. On September 22, 2011, EPA
ozone standards or contributing to a violation ofthe standards in a nearby area. Consistent withdesignations for previous ozone standards, EPA intends to designate an area as unclassifiable!

attainment ifthere are certified, quality-assured air quality monitoring data showing the area is meetingthe ozone standards or ifthere are no monitoring data for the area, and EPA has not made a

determination that the area is contributing to a violation in a nearby area.

After considering the District of Columbia’s March 11, 2009 ozone designation

recommendations and other relevant technical information, including 2008-2010 air quality data, EPAintends to support the District of Columbia’s recommended area designation and boundary for the

Washington-DC-MD-VA area. The enclosed Technical Support Document provides a detailed

analysis to support our preliminary decisions.

EPA will continue to work with District officials regarding the appropriate boundary for the

area in the District ofColumbia. Ifthe District of Columbia has additional information that the Districtwould like EPA to consider, please submit it to us by February 29,2012. EPA will also make its

preliminary designation decisions and supporting documentation available to the general public forreview and comment. We will be announcing a 30-day public comment period shortly in the Federal

Register. After considering additional information we receive, EPA plans to promulgate final ozone

designations in spring of 2012.

EPA is committed to working with the states and tribes to share the responsibility ofreducing

ozone air pollution. Current and upcoming federal standards and safeguards, including pollutionreduction rules for power plants, vehicles and fuels, will assure steady progress to reduce ozoneforming pollution and will protect public health in Communities across the country.

We look forward to a continued dialogue with you and your staff as we work together to

implement the 2008 ozone standards. If you have any questions, please do not hesitate to contact me

or have your staff contact Ms. Arnie Howell, EPA’s District ofColumbia Liaison, at (215) 814-5722.

Enclosure

cc: The Honorable Christophe A. 0. Tulou, Director

M. Garvin

Sincerely,

Regional Administrator

District Department of Environment