UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON O C 20480
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Cecentoer 16, 1986
Of*.C« o*
rom
Itw Honorable Lee Ttanas	* .o«.
Adainistrataor
U.S. Environmental Protection
Agency
Washington, DC 20460
Dear Mr. Thomas:
The Cl«an Air Scientific Advisory CaHiaittee (CASAC) nas consisted
its review of the 1986 Addandun 60 the 1982 Staff Pqper on Particulate
Matter (Haview of tha NAAQ6 fior Particulate Matteri Assessment of
Scientific and Technical Infoonation) prepared by the •Jtoancv's'ol?ioa
of Air Quality Planning and Standasds (QftQpS).
The Gonmittee unanimously ooncludes that this docuRmcit is consistent
in all significant respects with the scientific evidenae presented and
interpreted in the conbined Air Quality Criteria Docunant for Particulate
Matter/Sulfur Oxides and its 1986 Addendum, on which the GASAC recently
issued its closure letter. The Gonoittee believes that this docunent
provides you with the kind and amount of technical guidanoe that will
be needed to make appropriate revisions to the standards. The Conaittee's
major findings and conclusions concerning the various scientific issues
and studies discussed in the Staff Paper Addendum are contained in the
attached report.
Thank you Cor the opportunity	m on
this important public health issue.
cc: A. James Barnes
Gerald Qmison
Vaun Nevill
John O'Connor
Craig Potter
%rry Yosie
Morton UppnaravPh.D.
Chaixsan
Clean Air Scientific Advisory

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SAfe-CASAgi-67-OlO
SOtfUlY OP >ftJOR SCIENTIFIC ISSUES AND CASAC
OCWCLUSICNS ON TOE 1986 DRAFT ADDENDUM
TO 1SE 1982 PARTICULATE MAKER STAFF PAPER
The Committee found the technical discussions contained in the Staff
Paper Addendum to be acceptable with minor revision*.
Particle Size Indicator
The CASAC reaffirms its January 29, 1982 recxmraendation that a particle
size indicator that Includes only thcee particles less than or equal to a
ncrainal 10 unt aerodynamic diameter, termed PMiq, is appropriate for regulation
of particulate concentrations. This judpant is baaed on analysis of the
earlier available data, and the analysis of the recent scientific studies
discuaaed in the 1986 Addendum to the Air Quality Criteria for Particulate
Matter/Sulfur Oxides and the 1986 Addendum to the Particulate Natter Staff
Paper.
Implications of London Mortality Studies
m Further analyses of the London mortality studies, including recent
analysis by Agency staff, suggest that*
1)	the data provide no evidence Cor a threshold far the association
between airborne particles and daily mortality or a change of
coefficient with changes in particle composition?
2)	mortality effects can be associated with PM alone (with or
without sulfur oxides);
3)	there is no reliable quantitative basis far converting
British Smoke (BS) readings to 5«xo gravimetric mass
at law (<100-200 ug/ta3) 18 lewis, and henoe the mortality
data are not readily useful, for establishing a lower bound foe
24-hour PM]_o NMOS, although the suggestion of Mortality at
relatively low PM levels must be given serious consideration
in selecting a margin of safety.
interpretfwctlcn Studies for 24-hour Standard
Although the lung function decrements observed in children during and
after *ir pollution episodes are of uncertain health significance, the two
episodic lung function studies (Oocfeery et al., 198it Dassen et al., 1986)
are consistent with each other and the earlier work of Stabbings. Tfcsy
provide a relatively sensitive indication of possibls short tern physiological
responses. Given the difficulty in deriving a lower linlt froa the mortality
studies, these lung function studies can be useful in determining lower
bounds for a 24-hour P*io standard.

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Interpretation of the Six Cities Study for Annual Standard
In genes*!., the Committee Salt that the six cities data are useful in
establishing the lower bound of the range for the annual standard. In
addition, the following are suggested by the data;
1)	Cough and bronchitis, as defined in this study, are about twice
as prevalent in children living in cities with PM^q in the
range of 40-60 ug/n*3, in catperison to cities with 20-30 ug/m3;
2)	Because factors other than particulate natter may affect the
inter-city differences, it is difficult bo determine whether
these associations should be designated as "likely" health
effects?
3)	The results are consistent with the Oetro studies in terra of
morbidity responses at long-terra average particulate matter
exposures within current particulate aatoient air quality
standards; and
4)	The results are consistent with the Bouhuye study in terms
of symptoms without changes in pulmonary function.
Ranges for 24-hour and Annual Standards for PMm
In its January 2, 1986 letter to the Administrator, the CASAC noted
that its preliminary analyses of the more recent data do not indicate the
need for fundamental changes in the structure of the prupueed particle
standards; however, the Committee pointed out that these new data suggest
the need to focus consideration on standards at or perhaps below the lew
ends of the ranges proposed in the March 20, 1984 federal Register Notice.
The ranges of interest then piopussJ were 15
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