Lydia Wegman/RTP/USEPA/US 

03/07/2008 12:48 PM

	

To

hking@omb.eop.gov, mschwab@omb.eop.gov, rjohansson@omb.eop.gov

cc

martin.karen@epa.gov, hannon.john@epa.gov, Tricia
Crabtree/RTP/USEPA/US@EPA, Susan Stone/RTP/USEPA/US@EPA, Dave
Mckee/RTP/USEPA/US@EPA, richmond.harvey@epa.gov

Subject

Fw: edit to page 187









Heidi, Margo and Rob,

Please find below our revision to page 187 that we discussed yesterday. 
We can discuss it at 2 PM if you have any questions.

----- Forwarded by Lydia Wegman/RTP/USEPA/US on 03/07/2008 12:46 PM
-----

Karen Martin/RTP/USEPA/US 

03/07/2008 12:42 PM

	

To

Wegman Lydia@EPA

cc

Subject

edit to page 187









This is the edit that we said we would send to OMB -- starts on page 186
through 187.

c.	Conclusions on Level

	Having carefully considered the public comments on the appropriate
level of the O3 standard, as discussed above, the Administrator believes
the fundamental scientific conclusions on the effects of O3 reached in
the Criteria Document and Staff Paper, briefly summarized above in
section II.A.2 and discussed more fully in section II.A of the proposal,
remain valid.  In considering the level at which the primary O3 standard
should be set, the Administrator continues to place primary
consideration on the body of scientific evidence available in this
review on the health effects associated with O3 exposure, as summarized
above in section II.C.4.a, while viewing the results of exposure and
risk assessment, discussed above in section II.C.4.b, as providing
information in support of his decision.  In considering the available
scientific evidence he judges that, as at the proposal, a focus on the
proposed range of 0.070 to 0.075 ppm is appropriate in light of the
large body of controlled human exposure and epidemiological and other
scientific evidence.  As discussed above, this body of evidence does not
support retaining the current standard, as suggested by some commenters.
 Nor does it support setting a level above 0.075 ppm because such a
level would not provide a significant increase in protection compared to
the current standard, nor would such a level be appreciably below 0.080
ppm, the level in controlled human exposure studies at which adverse
effects have been demonstrated.  This body of evidence also does not
support setting a level of 0.060 ppm or below, as suggested by other
commenters.   The Administrator has also evaluated the information from
the exposure assessment and the risk assessment, and judges that this
evidence does not provide a clear enough basis for choosing a specific
level within the range of 0.075 to 0.070 ppm.  In making a final
judgment about the level of the O3 standard, the Administrator
particularly notes that the level of 0.075 ppm is above the range
recommended by the CASAC (i.e., 0.070 to 0.060 ppm).  Placing great
weight on the views of CASAC, the Administrator has carefully considered
its stated views and the scientific basis and policy views for the range
it recommended.  In so doing, the Administrator notes that he fully
agrees that the scientific evidence supports the conclusion that the
current standard is not adequate and must be revised.

Karen Martin, Ph.D.

Office of Air Quality Planning and Standards

U.S. EPA (C504-06)

Research Triangle Park, NC 27711

phone:  (919) 541-5274

fax:  (919) 541-0237

martin.karen@epa.gov

