UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

Mr. Barry R. Wallerstein 

Co-President and Co-Chair 

NACAA Mobile Sources and Fuels Committee 

National Association of Clean Air Agencies 

444 North Capitol Street, NW 

Washington, D.C. 20001 

Dear Mr. Wallerstein: 

MAR 2 5 2013 

OFFICE OF 

AIR AND RADIATION 

Thank you for your letter of January 22, 2013 , co-signed by Ms. Nancy Seidman, to the U.S. 

Environmental Protection Agency, urging the proposal of "Tier 3" light-duty vehicle emissions and 

gasoline standards and finalization of these standards by December 31, 2013. The. EPA is developing the 

Tier 3 standards to respond to the critical need to improve air quality and to enable a harmonized 

national vehicle emissions control program. The EPA shares your goal of reducing air pollution across 

the United States. The Tier 3 standards have the potential to achieve significant benefits. 

As mentioned in your letter, state and local agencies are challenged with finding effective emission 

reduction measures to meet their clean air obligations. This Tier 3 rule would reduce motor vehicle 

emissions and help state and local areas attain and maintain the existing health-based air quality 

standards in a cost-effective and timely way. The reductions in ozone and particulate matter would avoid 

premature mortality and other health impacts, including respiratory symptoms in children and 

exacerbation of asthma. 

The Tier 3 standards would, when finalized, create a comprehensive regulatory approach that provides 

certainty for both the auto and oil industries. Under a single harmonized national vehicle program, the 

Tier 3 standards under consideration would provide for coordinated implementation with the California 

vehicle program and the EPA and Department of Transportation's recently finalized light-duty vehicle 

standards to reduce carbon pollution and improve fuel economy for model years 2017 through 2025 . A 

timely Tier 3 program is critical to addressing the impacts of motor vehicles on air quality and public 

health; therefore, we intend to issue proposed Tier 3 standards in March of 2013 and finalize these 

standards by the end of 2013. 

Internet Address (URL) • http://www.epa.gov 

Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Postconsumer, Process Chlorine Free Recycled Paper 
We appreciate your bringing the N avigant Economics study to our attention, and we will consider this 

study as we develop the final rulemaking. Again, thank you for your letter and for your continued 

support of the Tier 3 program. I appreciate your commitment to achieving clean air for all citizens, and I 

look forward to continuing to work together towards that goal. 

cc: Mr. William Becker 

Executive Director 

Sincerely, 

i a McCarthy 

Assistant Administrator 
Nancy L. Seidman 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MAR 2 5 2013 

Co-Chair NACAA Mobile Sources and Fuels Committee 

National Association of Clean Air Agencies 

444 North Capitol Street, NW 

Washington, D.C. 20001 

Dear Ms. Seidman: 

OFFICE OF 

AIR AND RADIATION 

Thank you for your letter of January 22, 2013, co-signed by Mr. Barry Wallerstein, to the U.S. 

Environmental Protection Agency, urging the proposal of "Tier 3" light-duty vehicle emissions and 

gasoline standards and finalization of these standards by December 31 , 2013. The EPA is developing the 

Tier 3 standards to respond to the critical need to improve air quality and to enable a harmonized 

national vehicle emissions control program. The EPA shares your goal of reducing air pollution across 

the United States. The Tier 3 standards have the potential to achieve significant benefits. 

As mentioned in your letter, state and local agencies are challenged with finding effective emission 

reduction measures to meet their clean air obligations. This Tier 3 rule would reduce motor vehicle 

emissions and help state and local areas attain and maintain the existing health-based air quality 

standards in a cost-effective and timely way. The reductions in ozone and particulate matter would avoid 

premature mortality and other health impacts, including respiratory symptoms in children and 

exacerbation of asthma. 

The Tier 3 standards would, when finalized, create a comprehensive regulatory approach that provides 

certainty for both the auto and oil industries. Under a single harmonized national vehicle program, the 

Tier 3 standards under consideration would provide for coordinated implementation with the California 

vehicle program and the EPA and Department of Transportation's recently finalized light-duty vehicle 

standards to reduce carbon pollution and improve fuel economy for model years 2017 through 2025. A 

timely Tier 3 program is critical to addressing the impacts of motor vehicles on air quality and public 

health; therefore, we intend to issue proposed Tier 3 standards in March of 2013 and finalize these 

standards by the end of2013. 

Internet Address (URL) • http://www.epa.gov 

Recycled/Recyclable • Printed with Vegetable Oil Based Inks on 100% Postconsumer, Process Chlorine Free Recycled Paper 
We appreciate your bringing the Navigant Economics study to our attention, and we will consider this 

study as we develop the final rulemaking. Again, thank you for your letter and for your continued 

support ofthe Tier 3 program. I appreciate your commitment to achieving clean air for all citizens, and I 

look forward to continuing to work together towards that goal. 

Sincerely, 

ina McCarthy 

Assistant Administrator