Metropolitan Washington Air Quality Committee 

Suite 300, 777 North Capitol Street, N.E. Washington, D.C. 20002-4239 202-962-3358 Fax: 202-962-3203 

Mr. Robert Perciasepe 

Acting Administrator 

U.S. Environmental Protection Agency 

Ariel Rios Building 

1200 Pennsylvania Avenue, NW 

Washington, DC 20004 

Dear Mr. Perciasepe: 

I am writing on behalf of the Metropolitan Washington Air Quality Committee (MWAQC) to urge you to 

propose and finalize the Tier 3 vehicle emissions and gasoline standards during this calendar year. 

MWAQC is certified by the governors of Maryland and Virginia and the mayor of the District of 

Columbia to develop regional ground-level ozone and PM2.5 air quality plans and strategies for the 

Washington, DC-MD-VA non-attainment area. 

The Washington region has made great strides in cleaning the air thereby, reducing the health 

impacts of poor air quality, which cause a number of respiratory problems (e.g., asthma) and 

premature death. It has done so by lowering emissions of pollutants that produce smog and fine 

particles in the atmosphere. As a result, the region has met the annual fine particle standards, 

which were published in 1997 (15 .tg/m3 ) and 2013 (12 tg/m3 ) as well as daily fine particle 

standards, which were published in 1997 (65 jig/rn3 ) and 2006 (35 jig/rn3 ). Besides this, the 

region has also met the previous 1-hour ozone standard (0.12 ppm) published in 1979. However, 

there are tougher challenges ahead for the Washington region. The region needs to meet the 

current ozone standard (0.075 ppm) by 2015 and also needs to make sure that the region remains 

in attainment for the current fine particle standards (annual: 12 jig/rn 3 , daily: 35 jig/rn3 ). EPA is 

also planning to propose a possibly tougher ozone standard this year. EPA may also further 

tighten the fine particle standard in the future. 

In view of the challenges ahead for meeting and/or maintaining the tougher federal ozone and 

fine particle standards, the Washington region needs to reduce the emissions of pollutants 

producing ozone and fine particles (VOC, NOx, PM 25 , and SO2 ) significantly. The Tier 3 rule 

will help the Washington region immensely as it will provide cleaner gasoline and vehicles. This 

will also help the three jurisdictions in this region as they implement strategies to meet and/or 

maintain the above mentioned federal standards. 

Passenger vehicles are the largest emitters of nitrogen oxides (NOx) and one of the largest 

emitters of volatile organic compounds (VOCs), carbon monoxide (CO), and PM2.5 in the 

Washington region. A study by the National Association of Clean Air Agencies (NACAA) 

estimated that the Tier 3 program can reduce gasoline vehicle emissions of nitrogen oxides, 

carbon monoxide, and volatile organic compounds by 29, 38 and 26 percent respectively.
Reductions in emissions of the above pollutants will cause reduction in the levels of ozone, fine 

particles, and carbon monoxide. Clearly, implementation of the Tier 3 rule will lead to 

significantly cleaner air in the Washington region, providing important health benefits to 

millions of people. 

MWAQC urges you to finalize this rule by the end of 2013 so we don't delay and lose a full 

model year of emissions reductions. 

(1I( & 

Hon. Leta Mach, Chair 

Metropolitan Washington Air Quality Committee
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