UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON D.C. 20460 

 

OFFICE OF THE ADMINISTRATOR 

 SCIENCE ADVISORY BOARD 

February 19, 2010 

EPA-CASAC-10-007 

The Honorable Lisa P. Jackson 

Administrator 

U.S. Environmental Protection Agency 

1200 Pennsylvania Avenue, N.W. 

Washington, D.C. 20460 

Subject: Review of EPA’s proposed Ozone National Ambient Air Quality Standard 

(Federal Register, Vol. 75, Nov. 11, January 19, 2010) 

Dear Administrator Jackson: 

At the request of EPA’s Office of Air Quality Planning and Standards (OAQPS), the 

Clean Air Scientific Advisory Committee (CASAC) Ozone Review Panel for the 

Reconsideration of the 2008 National Ambient Air Quality Standard (NAAQS) met via 

teleconference on January 25, 2010 to review EPA’s proposed NAAQS for ozone announced in 

the Federal Register on January 19, 2010 (see Enclosure for roster.) OAQPS asked CASAC for 

any “additional comment” on EPA’s proposed ozone (O3) standards. 

CASAC fully supports EPA’s proposed range of 0.060 – 0.070 parts per million (ppm) 

for the 8-hour primary ozone standard. CASAC considers this range to be justified by the 

scientific evidence as presented in the Air Quality Criteria for Ozone and Related Photochemical 

Oxidants (March 2006) and Review of the National Ambient Air Quality Standards for Ozone: 

Policy Assessment of Scientific and Technical Information, OAQPS Staff Paper (July 2007). As 

stated in our letters of October 24, 2006, March 26, 2007 and April 7, 2008 to former 

Administrator Stephen L. Johnson, CASAC unanimously recommended selection of an 8-hour 

average ozone NAAQS within the range proposed by EPA (0.060 to 0.070 ppm).* In proposing 

this range, EPA has recognized the large body of data and risk analyses demonstrating that 

retention of the current standard would leave large numbers of individuals at risk for respiratory 

effects and/or other significant health impacts including asthma exacerbations, emergency room 

visits, hospital admissions and mortality. 

CASAC also supports EPA’s secondary ozone standard as proposed: a new cumulative, 

 

*

 See Letters from CASAC Chair Rogene Henderson, EPA-CASAC-07-001 (October 24, 2006), EPA-CASAC-07-

002 (March 26, 2007) and EPA-CASAC-08-000 (April 7, 2008) respectively. 
 2

seasonal standard expressed as an annual index of the sum of weighted hourly concentrations 

(i.e., the W126 form), cumulated over 12 hours per day (8am to 8pm) during the consecutive 3-

month period within the ozone season with the maximum index value, set as a level within the 

range of 7 to 5 ppm-hours. This W126 metric can be supported as an appropriate option for 

relating ozone exposure to vegetation responses, such as visible foliar injury and reductions in 

plant growth. We found the Agency’s reasoning, as stated in the Federal Register notice of 

January 19, 2010, to be supported by the extensive scientific evidence considered in the last 

review cycle. In choosing the W126 form for the secondary standard, the Agency acknowledges 

the distinction between the effects of acute exposures to ozone on human health and the effects 

of chronic ozone exposures on welfare, namely that vegetation effects are more dependent on the 

cumulative exposure to, and uptake of, ozone over the course of the entire growing season 

(defined to be a minimum of at least three months). In this proposal, the Agency is responding 

to the clear need for a secondary standard that is different from the primary standard in averaging 

time, level and form. 

As required by the law, CASAC’s recommendations are made without consideration of 

the cost or feasibility of implementation, considerations that are a part of the regulatory impact 

analysis. Although health and welfare effects of ozone will occur regardless of the origin of the 

ozone (i.e., natural, U.S. anthropogenic emissions or internationally transported emissions), we 

note that as levels for ozone standards move closer to “background” levels, new issues may arise 

with implementation. As the Agency moves forward with the next ozone review cycle, it would 

be well advised to carefully consider any new monitoring and implementation issues that may 

arise, particularly as background levels vary throughout the country. In addition, with 

implementation of the new W126 form for the secondary standard, we suggest that EPA collect 

information and seek additional research that could be used to inform continued refinement of 

the standard as well as its implementation. 

As always, we thank the Agency for the opportunity to provide advice on the proposed 

ozone NAAQS. 

Sincerely, 

 /Signed/ 

Dr. Jonathan M. Samet, Chair 

Clean Air Scientific Advisory Committee 

Enclosure 
 3

 

Enclosure 

U.S. Environmental Protection Agency 

Clean Air Scientific Advisory Committee (CASAC) 

Ozone Review Panel for the Reconsideration of the 2008 NAAQS 

CHAIR 

Dr. Jonathan M. Samet, Professor and Flora L. Thornton Chair, Department of Preventive 

Medicine, University of Southern California, Los Angeles, CA 

 

MEMBERS 

Dr. Joseph D. Brain, Cecil K. and Philip Drinker Professor of Environmental Physiology, 

Department of Environmental Health, Harvard School of Public Health, Boston, MA 

Dr. H. Christopher Frey, Professor, Department of Civil, Construction and Environmental 

Engineering, College of Engineering, North Carolina State University, Raleigh, NC 

Dr. Donna Kenski, Data Analysis Director, Lake Michigan Air Directors Consortium, 

Rosemont, IL 

Dr. Armistead (Ted) Russell, Professor, Department of Civil and Environmental Engineering, 

Georgia Institute of Technology, Atlanta, GA 

Dr. Helen Suh, Associate Professor, Department of Environmental Health, School of Public 

Health, Harvard University, Boston, MA 

Dr. Kathleen Weathers,*

 Senior Scientist, Cary Institute of Ecosystem Studies, Millbrook, NY 

CONSULTANTS 

Dr. John R. Balmes, Professor, Department of Medicine, Division of Occupational and 

Environmental Medicine, University of California, San Francisco, CA 

Dr. Ellis B. Cowling, University Distinguished Professor At-Large Emeritus, Colleges of 

Natural Resources and Agriculture and Life Sciences, North Carolina State University, Raleigh, 

NC 

*

 Did not participate in this review. 
 4

Dr. James Crapo, Professor of Medicine, Department of Medicine , National Jewish Medical 

and Research Center, Denver, CO 

Dr. William (Jim) Gauderman, Professor, Department of Preventive Medicine, University of 

Southern California, Los Angeles, CA 

Dr. Paul J. Hanson, Distinguished R&D Staff Member, Environmental Sciences Division, Oak 

Ridge National Laboratory, Oak Ridge, TN 

Dr. Jack Harkema, Professor, Department of Pathobiology, College of Veterinary Medicine, 

Michigan State University, East Lansing, MI 

Dr. Rogene Henderson, Senior Scientist Emeritus, Lovelace Respiratory Research Institute, 

Albuquerque, NM 

Dr. Philip Hopke, Bayard D. Clarkson Distinguished Professor, Department of Chemical and 

Biomolecular Engineering, Clarkson University, Potsdam, NY 

Dr. Michael T. Kleinman, Professor, Department of Medicine, Division of Occupational and 

Environmental Medicine, University of California, Irvine, Irvine, CA 

Dr. Allan Legge, President, Biosphere Solutions, Calgary, Alberta, Canada 

Dr. Morton Lippmann, Professor, Nelson Institute of Environmental Medicine, New York 

University School of Medicine, Tuxedo, NY 

Dr. Frederick J. Miller, Independent Consultant, Cary, NC 

Dr. Maria Morandi, Assistant Professor, Division of Environmental and Occupational Health, 

School of Public Health, University of Texas, Houston, TX 

Mr. Richard L. Poirot, Environmental Analyst, Air Pollution Control Division, Department of 

Environmental Conservation, Vermont Agency of Natural Resources, Waterbury, VT 

Dr. Charles Plopper, Professor, Department of Anatomy, Physiology and Cell Biology, School 

of Veterinary Medicine, University of California, Davis, California 

Dr. Elizabeth A. (Lianne) Sheppard, Professor, Biostatistics and Environmental & 

Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA 

Dr. Frank Speizer, Edward Kass Professor of Medicine, Channing Laboratory, Harvard 

Medical School, Boston, MA 

Dr. James Ultman, Professor, Chemical Engineering, Bioengineering Program, Pennsylvania 

State University, University Park, PA 
 5

Dr. Sverre Vedal, Professor, Department of Environmental and Occupational Health Sciences, 

School of Public Health, University of Washington, Seattle, WA 

Dr. Barbara Zielinska, Research Professor, Division of Atmospheric Sciences, Desert Research 

Institute, Reno, NV 

SCIENCE ADVISORY BOARD STAFF 

Dr. Holly Stallworth, Designated Federal Officer, Science Advisory Board Staff Office, 

Washington, D.C.