_ UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 20480
OmCEOF
THE ADMINISTRATOR
August 31,1992
EPA-SAB-CASAC-COM-92-009
Honorable William K. Roilly
Administrator
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, DC 20460
Dear Mr. Reilly:
The members of the Clean Air Scientific Advisory Committee (CASAG) have noted with
Interest the announcement that the Agency is not revising the national air quality standard for
ground-level ozone at this time and is initiating a new assessment of the health and
environmental effects of ozone. The purpose of this letter is to indicate the willingness of the
CASAC to assist the Agency in carrying out a review of the new assessment in an
expeditious manner. To facilitate CASAC involvement, it would be useful for the Committee
to be briefed at an early date on the Agency's plans for development of the new criteria
document on the health and environmental effects of ozone and the subsequent
development of a staff position paper on the ozone standard(s),
A briefing for CASAC would provide the opportunity for both CASAC and other
interested persons to comment on the Agency's plan for carrying out the important task of
preparing new documents. With this as background, CASAC can plan its associated review
of the criteria document and staff position paper in a timely manner. The briefing would also
provide an opportunity for the Agency and other scientists to describe the state of research
now in progress on ozone that will potentially be completed and subjected to peer-review in
time for its inclusion in a new assessment This is especially important since research on
ozone is, and should be, ongoing because of the importance of ozone as a pollutant.
Nonetheless, it is crucial that at a particular point in time, that is understood by ail parties, the
knowledge base on ozone be summarized and used for regulatory purposes. A side benefit
of the summarization process is that it can also serve to identify information needs which in
turn provides input for establishing the research agenda for the future.
The CASAC members are of the opinion that a carefully planned strategy for
preparation of the criteria document and staff position paper is essential in view of the
magnitude and complexity of the task. As you and your staff are aware, substantial new
information has been published since the last criteria document and supplement and staff
position paper were prepared. Other studies which may yield significant new information
Primed an Rtcycltd Paper
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Honorable William K. Reilly -2- August 31,1992
include the National Toxicology Program chronic bioassay with rodents exposed to ozone
and new human exposure assessment models are nearing completion. The review,
integration and interpretation of the old and new information will be a substantial undertaking.
In addition, it will be imperative that the next staff position paper carefully consider alternative
forms of the ozone standard, both in terms of averaging times, such as daily (6-24 hour), as
well as frequency of occurence, and seasonal standards, in addition to the traditional one
hour standard. This, too, will require substantial preparation effort and, I suspect, ample time
for debate.
The CASAC is anxious to assist in these important activities and looks forward to
hearing from you as to when the Agency will be ready to brief CASAC on the proposed plans
for preparation and review of the ozone criteria document and staff paper.
Sincerely,
Roger (X McClellan, D.V.M.
Chairman, Clean Air
Scientific Advisory Committee
ROM:eam
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