UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON B.C. 20460
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OFFICE OF THE ADMINISTRATOR
SCIENCE ADVISORY BOARD
February 19, 2010
EPA-C AS AC-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
(FederalRegister, 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 (Os) 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.
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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 (Sam 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 15 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
ozoneNAAQS.
Sincerely,
/Signed/
Dr. Jonathan M. Samet, Chair
Clean Air Scientific Advisory Committee
Enclosure
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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, Gary 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.
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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, C A
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, Gary, 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
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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.
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