UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20480
May 16, 1994
OFFICE OF THE ADMINISTRATOR
EPA-SAB-CASAC-CQM-94-005 scEN^Aoveofw HOARD
The Honorable Carol M. Browner
Administrator
U.S. Environmental Protection Agency
401 M Street, SW(1101)
Washington, DC 20460
Subject: Data Sets for PMW
Dear Ms, Browner:
As you are aware, the Agency is in the early stages of preparing an updated document on
"Air Quality Criteria for Particulate Material" which will in turn lead to a related Staff Position
paper. The Agency stiff has briefed the Clean Air Scientilc Advisory Committee (CAS AC) on
the plans for developing the two documents. CASAC is charged with reviewing the scientific and
technical underpinnings of Agency proposals for National Ambient Air Quality Standards. As
scientists affiliated with CASAC, we are concerned that the appropriate analyses be conducted
prior to our review.
In that spirit, we request that the Agency take steps to assure that crucial data sets linking
exposure to particulate matter and health responses are available for analysis by multiple analytical
teams, thereby assuring the validity of the results before they are used in making regulatory
decisions on the National Ambient Air Quality Standards for Particulate Material.
From the Agency briefings, it is clear that substantial new data are available that will need
to be considered in the new Criteria Document and Staff Position Paper, In particular, several
recent published reports have indicated effects on both morbidity and mortality at about the level
of the current PM,0 standard. In some cases, the analyses are extremely complex because of the
need to correct a wide range of potential confounders, such as temperature, cigarette smoking and
other pollutants.
It is already apparent that these analyses and the related published papers will have a
central role in the Criteria Document and Staff Position Paper, the related discussions and
recommendations of the Clean Air Scientific Advisory Committee, and in your final decision on
reaffirmation or revision of the standard for particulate material. In view of their importance, it is
crucial that two or more groups analyze the same key data sets linking exposure and
morbidity/mortality response to verify the adequacy of the complex analyses and that different
analysts using the same data reach similar conclusions. The importance of such validations and
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The Honorable Carol M. Browner
Page 2
May 16, 1994
the difficulty in carrying them out was apparent from presentations on PMJO effects at a recent
meeting at the National Academy of Sciences Beckman Center in Irvine, C A, At that meeting,
divergent results were obtained by two different analytical teams which were reputed to have
analyzed the same data. As it turned out, the data sets for the same city and time period analyzed
by the two research teams had subtle differences. Hence, we are left with uncertainty as to the
validity of either reported analysis.
The answer to this dilemma seems clear: The EPA should take the lead in requesting that
investigators make available the primary data sets being analyzed so that others can validate the
analyses- Further, the Agency should actively facilitate the conduct of such validating analyses.
For example, the Agency could take steps to insure that the data are made available in an
electronic media format that will facilitate transfer of the data to other teams for analysis.
Efforts such as we have proposed may to time-consuming and require some expenditures.
Nonetheless, modest expenditures to assure the scientific validity of key analyses that impact on
regulatory decisions would seem to be appropriate investments where the regulatory decisions
will have multibillion dollar impacts on society. Some might also argue that the kind of actions
recommended infringe on the rights of individual scientists to control their own data. This is
obviously a hollow argument recognizing that in almost all instances federal funds were used at
least to some extent to obtain the original data. Moreover, it would appear that the steps outlined
are essential steps for the Agency to take if it is to assure the scientific validity of any
reaffirmation or revision of the National Ambient Air Quality Standards for Paniculate Material.
The Clean Air Scientific Advisory Committee would appreciate being advised of the
Agency's plans for addressing the issues we have raised.
Sincerely,
George T. Wolff, Ph.D.
Chair, Clean Air Scientific
Advisory Committee
Roger 0, McClellan, D.V.M.
Past Chair, Clean Air Scientific
Advisory Committee
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