# Petition for Writ of Certiorari — American Iron & Steel Institute v. United States Environmental Protection Agency

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## Record

- **Collection:** Supreme Court brief
- **Document type:** Petition for Writ of Certiorari
- **Published:** January 1, 1991
- **Citation:** 498 U.S. 1082

## Text

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No. } JOSEPH P. SPANIOL, JR.

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IN THE

Supreme Court of the United States

OCTOBER TERM, 1990

AMERICAN IRON AND STEEL INSTITUTE,
Petitioner,
Vv.

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY,
Respondent.

PETITION FOR A WRIT OF CERTIORARI TO THE
UNITED STATES COURT OF APPEALS
FOR THE DISTRICT OF COLUMBIA CIRCUIT

Of Counsel: ROBERT A. EMMETT
BARTON C. GREEN (Attorney of Record)
AMERICAN IRON AND REED SMITH SHAW & McCLAY
STEEL INSTITUTE 1200 18th Street, N.W.
Washington, D.C. 20036
(202) 457-6144
Attorney for Petitioner

American Iron and

October 1, 1990 Steel Institute

WIL9ON - Eps PrinTING Co., INc. - 789-0096 - WASHINGTON, D.C. 20001

:
|

QUESTION PRESENTED

1. Whether the Environmental Protection Agency, in re-
vising the national ambient air quality standard for
particulate matter, violated Section 109(b) (i) of the
Clean Air Act when it failed to determine the par-
ticulate matter level that it deems to be safe to “pro-
tect the public health” and separately to determine
the additional protection necessary to provide an
“adequate margin of safety,” in each case articulat-
ing the scientific basis for its determination.

(i)

ii

LIST OF PARTIES TO THE PROCEEDING BELOW

The case below was raised in six petitions for review
of federal agency action filed in and consolidated by the
United States Court of Appeals for the District of Co-
lumbia Circuit and docketed at Nos. 87-1438, 87-1441,
87-1442, 87-1448, 88-1913, and 89-1013. This Petition
for a Writ of Certiorari is based on claims presented in
petitions Nos. 87-1442, 87-1443, and 88-1913.

In Nos. 87-1442 and 87-1448, the American Iron and
Steel Institute (“AISI”)' was the petitioner, Alabama
Power Company, et al.,?> and the American Mining Con-

1 AISI is a trade association. AISI is not a corporation and does
not have a parent or subsidiary company to be listed pursuant to
Rule 29.1 of the Rules of the Supreme Court. Upon request, counsel
can compile and supply to the Court a list of AISI’s member
companies.

2“Alabama Power Company, et al.,” refers to Alabama Power
Company, Appalachian Power Company, Baltimore Gas and Electric
Company, Boston Edison Company, Carolina Power & Light Com-
pany, Centerior Energy Corporation, Cleveland Electric Illuminating
Company, Toledo Edison Company, Central and South West Serv-
ices, Inc., Central Power and Light Company, Public Service Com-
pany of Oklahoma, Southwestern Electric Power Company, West
Texas Utilities Company, Central Hudson Gas & Electric Corpora-
tion, Central Illinois Light Company, Central Illinois Public Service
Company, The Cincinnati Gas & Electric Company, Columbus South-
ern Power Company, Commonwealth Edison Company, Consolidated
Edison Company of New York, Inc., Consumers Power Company,
The Dayton Power and Light Company, Delmarva Power & Light
Company, The Detroit Edison Company, Duke Power Company,
Florida Power Corporation, Florida Power & Light Company,
Georgia Power Company, Gulf Power Company, Houston Lighting
& Power Company, Illinois Power Company, Indiana Michigan
Power Company, Indianapolis Power & Light Company, Iowa-
Illinois Gas and Electric Company, Iowa Public Service Company,
Kansas City Power & Light Company, Kentucky Power Company,
Kentucky Utilities Company, Madison Gas and Electric Company,
Mississippi Power Company, Monongahela Power Company, Montaup
Electric Company, New England Power Company, New York State
Electric & Electric Gas Corporation, Northern Indiana Public Serv-

lll

gress (“AMC”) were intervenor-petitioners, the United
States Environmental Protection Agency (“EPA”) and
the Administrator of the United States Environmental
Protection Agency (“Administrator”) were respondents,
and the Natural Resources Defense Council, Ince.
(“NRDC”) was intervenor-respondent.

In No. 88-1913, AISI was petitioner, Alabama Power
Company, et al., were intervenor-petitioners, EPA was
respondent, and NRDC was intervenor-respondent.

In No. 87-1438, NRDC, the State of Connecticut, the
Commonwealth of Massachusetts, the State of New Jer-
sey, the State of New York, and the State of Vermont
were petitioners, the Administrator and EPA were re-
spondents, and Alabama Power Company, et al., AISI,
AMC, and the National Coal Association (“NCA”) were
intervenor-respondents.

In No. 87-1441, AMC was petitioner, Alabama Power
Company, et al., and AISI were intervenor-petitioners,
the Administrator and EPA were respondents, and
NRDC was intervenor-respondent.

In No. 89-1013, AMC was petitioner, Alabama Power
Company, et al., and NCA were intervenor-petitioners,
EPA was respondent, and NRDC was _intervenor-
respondent.

ice Company, Ohio Edison Company, Pennsylvania Power Company,
Ohio Power Company, Ohio Valley Electric Corporation, Oklahoma
Gas and Electric Company, Pacific Gas and Electric Company,
Pennsylvania Electric Company, Pennsylvania Power & Light Com-
pany, The Potomac Edison Company, Potomac Electric Power Com-
pany, Public Service Company of Indiana, Inc., Public Service Elec-
tric and Gas Company, Salt River Project, Southern California
Edison Company, Tampa Electric Company, Tucson Electric Power
Company, Union Electric Company, Virginia Power Company, West
Penn Power Company, Wisconsin Electric Power Company, Wis-
consin Power and Light Company, Wisconsin Public Service Cor-
poration, the Edison Electric Institute, the National Rural Electric
Cooperative Association, and the American Public Power Association.

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TABLE OF CONTENTS

QUESTION PRIEGIENTED quan .seneeseeceenesesenee

LIST OF PARTIES TO THE PROCEEDING BE-
LOW ...... ‘ .

ey Be i yi fy |
8, SC ee ae
JURISDICTION .................
STATUTE AND REGULATIONS INVOLVED ...........

STATEMENT OF THE CASE ooo... .eeeeeeeceneeeenneeeee

A. EPA’s National Ambient Air Quality Standards
for Particulate Matter ..........................................

B. The Proceedings Below ...................---0.cc-.ccccceeeeeeeeee

REASONS FOR GRANTING THE WRIT .....................

I. EPA MUST IDENTIFY A SAFE EXPOSURE
LEVEL FOR THE POLLUTANTS IT REGU-
LATES UNDER SECTION 109 .............

II. BY FAILING TO DEFINE SAFE EXPOSURE
LEVELS FOR ITS SECTION 109 STAND-
ARDS EPA HAS EXCEEDED ITS STATU-
TORY AUTHORITY AND PREVENTED
MEANINGFUL JUDICIAL REVIEYW ...............

CORY cents cnteiissnttuiinsinineabiainaiaiieitcheaiciniiansiiiciladhintaeen

APPENDIX

A. FINAL RULE OF THE UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY:
Revisions to the National Ambient Air Quality
Standards for Particulate Matter, 52 Fed. Reg.
24634 (July 1, 1987) (excerpts) —......00000..0..

B. STATUTORY PROVISIONS .....02 eee

(v)

mn wp wo em GC.

10

15
17

vi

TABLE OF AUTHORITIES

CASES: Page
A.L.A. Schechter Poultry Corp. v. United States,
BOE UB. GBE (IBGE) q.........-...n0nseecees--cccccerenccssereseee 16

American Petroleum Institute v. Costle, 665 F.2d
1176 (D.C. Cir. 1981), cert. denied, 455 US.

1084 (1982) (Ozone) .................-...........sceeseeeseee 11, 18, 15
Burlington Truck Lines v. United States, 371 U. S.

| 7) | 16
Industrial Union Dep’t., AFL-CIO v. American

Petroleum Inst., 448 U.S. 607 (1980) ................... 16

Lead Industries Association v. EPA, 647 F.2d
1180 (D.C. Cir.), cert. denied, 449 U.S. 1042
(RBBB) CLC) 2a -aaenceaccecesceccssecccemnsecesessessnssesnsnence 11, 18, 15
Natural Resources Defense Council, Inc. v. Admin-
istrator, U.S. Environmental Protection Agency,
824 F.2d at 1146 (D.C. Cir. 1987) (en banc)
(Vinyl Chloride) ..................-.----s-eeee- 8, 9, 11, 12, 18, 14
Natural Resources Defense Council, Inc., et al. v.
Administrator, U.S. Environmental Protection

Agency, et al., 902 F.2d 962 (D.C. Cir. 1990)... 1,9,
18, 15

Panama Refining Co. v. Ryan, 293 U.S. 388
CII aencenenceceresenerssnssarsnersnenerecesasssennnneneetsenscnmnnenen 16

STATUTES:
28 U.S.C. § 1254 (1) (1988) ............--.-..----eeceeceeeeeeees 2
28 U.S.C. § 2101 (c) (1988) ...........--.-------c-eceeeeeeeeeeeees 2
Clean Air Act, 42 U.S.C. § 7401, et seq. (1982) :

Section 108, 42 U.S.C. § 7408 (1982) ................. 2,10

Section 108(a) (1), 42 U.S.C. § 7408(a) (1)

CRED anenenecseveessernescsennseeesesensaneessnnscensnenesetenetans 4
Section 109, 42 U.S.C. § 7409 (1982) ................. passim
Section 109 (a), 42 U.S.C. § 7409(a) (1982)... 4
Section 109(b) (1), 42 U.S.C. § 7409(b) (1)

CRIED nan cacenencennnnneneeetenscnncemnsewnnqeencennnnnneenennonse 4,10
Section 110(a) (2) (I), 42 U.S.C. § 7410(a)

CB) CH) CRG) naan nana nnnnsncenn-arecenvsccnceresenesseseseee 3
Section 112, 42 U.S.C. § 7412 (1982) ......... 2, 8, 9, 11,

12, 18, 14

Section 113(a), 42 U.S.C. § 7415 (a) (1982).. 3

vii
TABLE OF AUTHORITIES—Continued

LEGISLATIVE MATERIALS:

2 Sen. Comm. on Public Works, 98d Cong., 2d
Sess., Air Quality and Automobile Emission
Control 401 (Comm. print ES

FEDERAL REGISTER:

MISCELLANEOUS:

Jorling, The Federal Law of Air Pollution Control,
FEDERAL ENVIRONMENTAL Law, 1066 (1974)...
National Air Quality Criteria Advisory Commit-
tee, Science Advisory Board, Report on Air
Quality Criteria for Particulate Matter (1976) ..
Regulatory Impact Analysis of the National Am-
bient Air Quality Standards for Particulate
Matter, Second Addendum (Dec. 1986) ..............

IN THE

Supreme Court of the United States

OCTOBER TERM, 1990

No.

AMERICAN IRON AND STEEL INSTITUTE,

7 Petitioner,
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY,
Respondent.

PETITION FOR A WRIT OF CERTIORARI TO THE
UNITED STATES COURT OF APPEALS
FOR THE DISTRICT OF COLUMBIA CIRCUIT

The American Iron and Steel Institute (“AISI”) re-
spectfully petitions for a writ of certiorari to review the
judgment of the United States Court of Appeals for the
District of Columbia Circuit entered or April 27, 1990,
in the case of Natural Resources Defense Council, Inc.,
et al. v. Administrator, U.S. Environmental Protection
Agency, et al., No. 87-1438 and consolidated cases.

OPINION BELOW

The April 27, 1990 opinion of the United States Court
of Appeals for the District of Columbia Circuit in Nat-
ural Resources Defense Council, Inc., et al. v. Adminis-
trator, U.S. Environmental Protection Agency, et al., No.
87-1438 and consolidated cases, is reported at 902 F.2d
962 and is reprinted in the Appendix to the Petition for
a Writ of Certiorari (No. 90-257) filed by the National
Coal Association (“NCA App.”) at la.’

1 The Petition in No. 90-257, National Coal Association v. Natural
Resources Defense Council, Inc., et al., is from the same judgment

2

The opinion below addresses final rulemaking pub-
lished by the United States Environmental Protection
Agency (“EPA”) entitled Revisions to the National
Ambient Air Quality Standards for Particulate Matter,
published at 52 Fed. Reg. 24634 (July 1, 1987), perti-
nent portions of which are reprinted in the Appendix
(“App.”) to this Petition at la-53a.

JURISDICTION

The judgment of the United States Court of Appeals
for the District of Columbia Circuit was entered on
April 27, 1990. See NCA App. at la. A timely filed pe-
tition for rehearing was denied by that court on July 3,
1990. NCA App. at 93a. This Petition is filed within 90
days of the July 3, 1990 denial of the petition for re-
hearing in accordance with 28 U.S.C. 2101(¢c) (1988)
and Rules 13.1 and 13.4 of the Rules of this Court. This
Court’s jurisdiction is invoked pursuant to 28 U.S.C.
§ 1254(1) (1988).

STATUTE AND REGULATIONS INVOLVED

This case involves Section 109 of the Clean Air Act,
as amended, 42 U.S.C. § 7409 (1982). The pertinent
provisions of Section 109 and related Sections 108 and
112, 42 U.S.C. §§ 7408 and 7412 (1982), together with
the regulations at issue herein are set forth in Appendix
A and B hereto, respectively, at 54a and la.

STATEMENT OF THE CASE

This case addresses the manner in which EPA prop-
erly can exercise its far-reaching authority to set na-
tional ambient air quality standards under Section 109

of the court below which is the subject of this Petition. This Peti-
tion presents different questions from those raised in No. 90-257.
We believe the Court should grant review in No. 90-257 but do not
plan to file a pleading in response to the National Coal Association
Petition.

3

of the Clean Air Act.? Once EPA establishes a Section
109 standard, that standard, within statutorily-prescribed
time periods, must be met in every corner of the country.
Cities and industrial areas that fail to meet Section 109
standards are subject to severe regulatory and economic
sanctions.* Individual piants and sources deemed to be
contributing to air pollutant levels that exceed a Section
109 standard must install emission controls which re-
quire major expenditures for nonproduction-related
equipment. Sources that violate their control require-
ments are subject to enforcement proceedings and civil
penalties or criminal fines of $25,000 per day.*

As one commenter noted in 1974:

The Clean Air Act, coupled with the new 1972 Water
Pollution Control Act Amendments, grants regula-
tory power to the administrator of EPA far beyond
that possessed by other traditional federal regulatory
commissions. These two environmental acts regulate
not just one or another industry type or practice, but
rather regulate nearly all industry, and, more im-
portantly, the behavior of all citizens, through trans-
portation and other controls.

Jorling, The Federal Law of Air Pollution Control, FEp-
ERAL ENVIRONMENTAL LAw, 1066 (1974). An unneces-
sarily stringent Section 109 standard can waste resources

242 U.S.C. § 7409 (1982). Hereinafter, citations to the Clean
Air Act are to sections of the Act. The Table of Authorities pro-
vides parallel citations to the United States Code.

3% See, generally, Part D of Title I of the Clean Air Act and, in
particular, Sections 172 (requiring the states to adopt stringent new
planning and regulatory mechanisms for areas not meeting an
NAAQS) and 176 (cutting off certain federal grants for areas not
meeting an NAAQS and failing to take remdial measures required
by Part D). See also, Section 110(a) (2) (1) (banning the construc-
tion or modification of major emission sources in areas not meeting
an NAAQS and lacking an approved Part D plan).

4 See Section 113(b), (c).

4

and impair American industry and its ability to compete
internationally.

Section 109 requires EPA to establish national am-
bient air quality standards to “protect the public health”
and further to specify an ‘adequate margin of safety.”
The D.C. Circuit ruled in the case below and on two
other occasions that EPA may set Section 109 standards
without identifying either the level at which a particular
pollutant is safe for the public health or the magnitude
of the safety margin it applied to its safe exposure de-
termination. The D.C. Circuit further stated in the de-
cision below that “uncertainty” in the data relied upon
by EPA made unnecessary any such “further articula-
tion” of EPA’s basis for its Section 109 standards.

A. EPA’s National Ambient Air Quality Standards for Par-
ticulate Matter

The Clean Air Act, as enacted in 1970, established,
among other things, a framework for the regulation of
common, ubiquitous air pollutants. EPA first was re-
quired to identify air pollutants emitted from “numerous
or diverse mobile or stationary sources” which in the
ambient air ‘‘may reasonably be anticipated to endanger
public health or welfare.” Section 108(a) (1). For each
pollutant so identified, EPA must issue national ambient
air quality standards (“standards” or “NAAQS’). Sec-
tion 109(a). So-called “primary” or health-related
NAAQS must be set at levels which “allowing an ade-
quate margin of safety, are requisite to protect the pub-
lic health.” Section 109(b) (1).

“Particulate matter” is a generic term for airborne
particles (liquid droplets or solids) of chemically and
physically diverse substances. Such particles originate
from many natural and man-made sources, both mobile
and stationary, ranging from dust storms, sea spray, and
voleanic activity to dirt roads and various industrial and
agricultural activities.

5

The first particulate matter NAAQS were adopted by
EPA in 1971 and were expressed in terms of Total Sus-
pended Particulate (“TSP”). TSP is a measure of par-
ticulate matter captured by an air sampling device known
as a high volume sampler, which collects particles up to
sizes of 25 to 45 micrometers.

In setting a 24-hour TSP primary standard in 1971,
EPA relied on effects levels reported by British scientists
in studies carried out in Greater London over two decades
starting in the 1950s. EPA erred, however, by treating
the British Smoke measurement units reported in the
British studies as equivalent to the more particle-inclusive
TSP measure used for the U.S. standards. This error,
although never publicly acknowledged by EPA, was noted
by the National Academy of Sciences in 1974° and by
EPA’s own appointed science advisors.*° By treating the
TSP measure as equivalent to the British Smoke measure,
EPA incorrectly ascribed adverse health effects to TSP
levels half as high as the levels reported in the British
studies upon which EPA relied.’ Because of this and other
errors, EPA’s science advisors concluded in 1976 that re-
vision of the scientific documents upon which the original
particulate matter standards were based was “not only
desirable, but necessary.” *

Eight — later, in 1984, EPA proposed revisions to
the particulate matter standards.® In the preamble

5 See 2 Sen. Comm. on Public Works, 93d Cong., 2d Sess., Air
Quality and Automobile Emission Control 401 (Comm. Print 1974).

6 See National Air Quality Criteria Advisory Committee, Science
Advisory Board, Report on Air Quality Criteria for Particulate
Matter (1976).

7 Id. at 27.
8 Jd. at 1.

® See Proposed Revisions to the National Ambient Air Quality
Standards for Particulate Matter, 49 Fed. Reg. 10408 (Mar. 20,
1984).

6

thereto, then EPA Administrator Ruckelshaus stated that
“the selection of a single air quality standard . . . pre-
sents an extraordinarily difficult regulatory problem, one
for which the existing legislative decision criteria may
well be inadequate.” 49 Fed. Reg. at 10409. He further
noted that the scientific data base for applying an ade-
quate margin of safety was “even more sparse and un-
certain,’ and that “[n]o ‘scientific’ approach for select-
ing any single recommended standard seems possible
against this background.” /d.

The Administrator noted that the courts “appear” to
have ruled out consideration of economic and technological
factors in setting ambient standards, leaving “some doubt
whether the Administrator may even consider the prac-
tical problems of implementation to guide his choice.” Jd.
EPA’s public health review as of that date “revealed no
scientific method of assessing exactly what level of stand-
ards public health requires. The scientific review indi-
cates substantial uncertainties concerning the health risks
associated with lower levels of particulate matter.” Jd.

Because of this “substantial degree of uncertainty,”
EPA proffered “ranges of interest’? from which the final
standards likely would be chosen. Jd. at 10415. EPA
proposed to select (1) a 24-hour primary standard from
a range of 150 to 250 micrograms per cubic meter (yg/
m*), and (2) an annual primary standard from a range
of 50 to 65 micrograms per cubic meter (ng/m*). Id. at
10408. EPA also proposed to replace TSP as the indi-
eator for particulate matter with a new, size-specific in-
dicator designed to measure only particles with an aero-
dynamic diameter equal to or smaller than 10 microm-
eters. Jd. EPA had determined that TSP particles larger
than 10 micrometers had no significant impact on health
and, therefore, should not be regulated. Jd. at 10412.
EPA referred to the new indicator as PM,,. Jd.

7

In its June 3, 1985 comments '® on the proposed PM,,
standards, AISI objected to EPA’s attempt to inject scien-
tific uncertainty as justification for maintaining the er-
roneously stringent TSP standards as a basis for the new
PM,, standards. By 1984, the scientific community, if not
EPA, generally had acknowledged that the present stand-
ards were scientifically invalid because of the faulty ap-
plication of British Smoke measurements.'! AISI also
quoted from remarks presented by Dr. A. Fraas of the
Office of Management and Budget noting that since EPA
was “unable to identify any clear evidence of adverse
health effects at or near current ambient levels, it has
made the uncertainty in the available evidence into a vir-
tue by arguing that the current statute requires a con-
servative approach to protecting public health.” !”

AISI further stated in its comments that EPA cannot
use the lack of scientific evidence absolutely ruling out
adverse health effects at low levels of PM,, exposure to
set the primary NAAQS essentially at any level it pleases.
Such use by EPA of Section 109, if permitted, would in-
dicate an excessive delegation to EPA of legislative power
which would raise Constitutional questions."

EPA promulgated the final standards on July 1, 1987."
EPA retained the PM,, indicator but selected the final
standards from the bottom of its proposed ranges. The
final 24-hour standard was set at 150 micrograms per
cubic meter (»g/m*), and the annual standard was set
at 50 micrograms per cubic meter (»g/m*). EPA’s reg-
ulatory impact analysis predicted that attaining the new

10 AISI’s June 3, 1985 comments (“AISI Comments’) were dock-
eted in the PM,, rulemaking proceeding at No. A-82-37, IV-D-254.

11 See p. 5 supra.
12 AISI Comments at 88.
13 AISI Comments at 98-101.

14 See Revisions to the National Ambient Air Quality Standards
for Particulate Matter, 52 Fed. Reg. 24634 (July 1, 1987), App. la.

q

8

standards at these levels would cost nearly $2 billion (dis-
counted present value in 1983),’° one tenth of which, or
approximately $200 million, will be borne by the steel
industry."®

On October 28, 1987, AISI submitted a Petition to EPA
for Reconsideration of the final standards on the basis of
(a) new health effects data which AISI submitted with
its Petition, and (b) the D.C. Circuit’s decision in Nat-
ural Resources Defense Council, Inc. v. Administrator,
U.S. Environmental Protection Agency, 824 F.2d 1146
(D.C. Cir. 1987) (en banc) (Vinyl Chloride) (holding
that EPA, in establishing emission standards for hazard-
ous air pollutants under Section 112 of the Act, must
separately determine a “safe” level of exposure prior to
applying an ample margin of safety). More than a year
later, EPA denied AISI’s Petition for Reconsideration."

B. The Proceedings Below

Pursuant to and under the authority of Section 307 (b)
(1) of the Act, AISI appealed EPA’s final standards and
EPA’s denial of AISI’s Petition for Reconsideration in
petitions for review filed in the D.C. Circuit and consoli-
dated with others in the case below. AISI challenged the
final standards on a number of scientific and legal grounds
as arbitrary and capricious and contrary to law. AISI
also pointed out that EPA failed to identify a safe level
for PM,, contrary to the requirements of Section 109 of
the Clean Air Act and contrary to the D.C. Circuit’s
Vinyl Chloride decision. :

The panel below excused EPA’s failure to denote a
“safe” level of exposure for PM,, by reasoning that the

15 Regulatory Impact Analysis of the National Ambient Air Qual-
ity Standards for Particulate Matter, Second Addendum (Dec. 1986)
at II-20.

16 Jd, at II-25.
17 See 53 Fed. Reg. 52698 (Dec. 29, 1988).

a

9

Vinyl Chloride decision construing Section 112 of the
Clean Air Act did not apply to determinations under Sec-
tion 109.** The court below found that the uncertainty of
the data upon which the Administrator based the final
standards made it unnecessary for EPA to articulate the
“risk it considered tolerable in meeting the requirements
of providing a reasoned explanation for an administra-
tive decision.”

Alabama Power Company, et al.,* intervenors in the
D.C. Circuit proceedings below, filed a timely petition for
rehearing and suggestion for rehearing en banc on an
unrelated issue involving acid deposition. The court below
denied the petition and suggestion on July 3, 1990.

REASONS FOR GRANTING THE WRIT

This Court has decided twelve cases arising under the
Clean Air Act since that act was first enacted twenty
years ago in 1970. To date, however, this Court has not
heard a case involving Section 109, the most pervasive
and far-reaching provision in the statute. Section 109
gives the Administrator the power to dictate the contents
of the air we breathe and in so doing can redirect mas-
sive capital investment from growth and increased pro-
duction to air emission control systems. To the extent
Section 109 standards are unnecessarily stringent, plants
may be shut down and jobs lost, with concomitant social
and economic dislocation and a variety of adverse direct
and indirect effects, including deterrence of new invest-
ment and impaired international competitiveness.

Although the impact of the PM,, standards is nation-
wide, only one court, the U.S. Court of Appeals for the
District of Columbia Circuit, may review their propriety.

18 Natural Resources Defense Council, Inc. v. Administrator, U.S.
Environmental Protection Agency, 902 F.2d 962, at 973-74, NCA
App. at 22a-23a.

19 Jd. at 974, NCA App. at 23a.

20 See p. ii n.2, supra, for a list of these companies.

10

See Section 307(b) (1). Any challenge to the PM,, stand-
ards must be brought within 60 days of promulgation.
Id. Thereafter, the PM,, standards are not subject to
challenge, not even as a defense in civil or criminal en-
forcement proceedings. Section 307(b)(2). The Clean
Air Act’s judicial review preclusion provisions thus elimi-
nate any possibility of a conflict among the circuits or
any further challenges to the PM,, standards. Unique
issues raised by the PM,, standards will not develop,
ripen, or otherwise become more focused in other forums
over time. Now that the D.C. Circuit has acted, only the
Supreme Court may address the issues raised by the
PM,, standard and only on this singular occasion.

I. EPA MUST IDENTIFY A SAFE EXPOSURE
LEVEL FOR THE POLLUTANTS IT REGULATES
UNDER SECTION 109

Congress did not and cannot make in Section 109 an
unfettered delegation to EPA of authority to set stand-
ards of critical and national importance. Section 109
(b) (1) requires that NAAQS

shall be ambient air quality standards the attainment
and maintenance of which in the judgment of the
Administrator, based on such criteria and allowing
an adequate margin of safety, are requisite to pro-
tect the public health.

On its face, Section 109(b) (1) thus imposes three, sepa-
rate limits upon EPA’s standard setting discretion.
First, Section 109(b) (1), requires that primary NAAQS
“shall be based on . . . criteria” identified pursuant to
Section 108. Second, primary NAAQS must be “requisite
to protect the public health.” Third, primary NAAQS
must allow an “adequate margin of safety.”

With regard to the first limit or requirement, that
NAAQS be based upon criteria identified by EPA pur-
suant to Section 108, AISI raised numerous objections
below to EPA’s mischaracterization and misuse of the
available scientific data in the particulate matter criteria

MMi

11

document and in setting the final primary PM,, stand-
ards. For example, as already noted,?* EPA misapplied
the British data upon which it relied in setting its origi-
nal 1971 TSP standards, making the TSP standards at
least twice if not three times too stringent, and never
acknowledged or corrected that error but rather per-
petuated it when EPA set the new PM,, standards.

For purposes of this Petition, however, AISI focuses
on the second and third requirements of Section 109.
EPA has failed to identify either the level of PM,, “req-
uisite te protect the public health” or the magnitude of
the “adequate margin of safety” which it applied to that
level. EPA declined to make similar determinations when
it established an NAAQS for lead in 1978. The D.C. Cir-
cuit upheld this omission in Lead Industries Association
v. EPA, 647 F.2d 1130 (D.C. Cir.), cert. denied, 449
U.S. 1042 (1980) (Lead). EPA again failed to make
these determinations in establishing a revised NAAQS
for ozone in 1979. The D.C. Circuit excused this omis-
sion in American Petroleum Institute v. Costle, 665 F.2d
1176 (D.C. Cir. 1981), cert. denied, 455 U.S. 1034 (1982)
(Ozone).

In 1976 and 1985, in separate proceedings respectively
establishing and retaining with minor revisions an emis-
sion standard for the hazardous air pollutant vinyl
chloride under Section 112 of the Clean Air Act, EPA
again did not identify a health effects threshold for vinyl
chloride, a strong carcinogen. Section 112 requires EPA
to establish standards governing emissions of hazardous
air pollutants at levels that “protect the public health”
with an “ample margin of safety.” Section 109 has simi-
lar requirements but requires a lesser, “adequate” mar-
gin of safety.

In the Vinyl Chloride case, supra, which reviewed
EPA’s withdrawal of proposed amendments to the Section
112 vinyl chloride standard, Petitioner Natural Resources

21 See p. 5 supra.

12

Defense Council, Inc. argued that the mandate to protect
the public health with an “ample” margin of safety re-
quired that all emissions of vinyl chloride be banned. See
824 F.2d at 1152. This contention was unanimously re-
jected by the D.C. Circuit sitting en banc. Id. at 1154.
Instead, the D.C. Circuit reversed and remanded the
vinyl chloride standard because EPA had failed to make
basic determinations required by the Act. The D.C. Cir-
cuit stated that, in setting national emission standards
for hazardous air pollutants under Section 112, “the con-
gressional mandate to provide ‘an ample margin of
safety’ ‘to protect the public health’ requires EPA to
make an initial determination of what is ‘safe’.” Jd. at
1164. EPA may not consider cost or technical feasibility
in determining what is “safe”; such a determination
must be “based solely upon the risk to health.” Jd. at
1166. Noting that “safe” does not mean “risk-free,” the
D.C. Circuit ruled that EPA “must” decide “what risks
are acceptable in the world in which we live.” Jd. at
1165. Once EPA has determined a “safe” level of ex-
posure, the D.C. Circuit found that EPA could weigh
considerations in addition to health such as cost or feasi-
bility in applying the “ample margin of safety’’ required
by Section 112. 7d.

The Vinyl Chloride decision was handed down shortly
after EPA issued the final PM,, standards. AISI sub-
mitted a Petition to EPA for Reconsideration of the final
PM,, standards, in part to give EPA an opportunity to
apply the Vinyl Chioride analysis and to evaluate the
degree of “safety” that would be provided by the various
levels within the ranges proposed for the primary PM,,
standards. Both EPA, in denying AISI’s Petition for
Reconsideration, and the court below refused to apply the
Vinyl Chloride rationale to EPA’s standard setting under
Section 109.

The court below found that “the two-step methodologi-
cal requirement endorsed by Vinyl Chloride was neces-

|

13

sary because of the need under § 112 to sever determina-
tions that must be based solely on health considerations
from those that may include economic and technological
considerations.” 902 F.2d at 973, NCA App. at 22a.
Noting its previous Lead and Ozone decisions (id., NCA
App. at 2la), the court below stated that EPA may not
consider cost or technoicgical feasibility at any stage of
standard setting under Section 109. Jd., NCA App. at
22a. Because of this, the court below found that the
rationale for separate identification of a safe level and
the margin of safety applied thereto was “inapposite” to
actions under Section 109. Jd. This “foreclosure from
consideration of cost and technological feasibility” per-
suaded the court below that Section 109 “itself does not
mandate the methodological requirement we found neces-
sary under § 112.” Id., NCA App. at 23a.

The concern of the court below over economic and
technological feasibility is misplaced. The mandate in
Sections 109 and 112 “to protect the public health” neces-
sitates a “safe” exposure level determination whether or
not EPA considers such other factors as economic or tech-
nological feasibility. See, Vinyl Chloride, 824 F.2d at
1164-65 & n.11.

The distinction between Section 112 for vinyl chloride
and Section 109 for PM,. proffered by the court below
makes no rational sense. Vinyl chloride is a “strong
carcinogen” with a long and uncertain latency period.”
The evidence in that case suggested that there was no
apparent safe exposure level for vinyl chloride.” Despite
the extreme dangers and substantial uncertainties posed
by the chemical in question, the D.C. Circuit in Vinyl
Chloride found that EPA’s standard setting responsibili-
ties included the identification and determination of cer-
tain parameters such as a safe exposure level and the

22 Vinyl Chloride, 824 F.2d at 1148.
23 Id.

14

magnitude of the margin of safety applied to that level.
With respect to PM,., however, a relatively benign pol-
lutant at lower concentration levels with only minimal
transitory effects on even the most sensitive populations,
the court below declined te impose the minimal procedural
requirements the Vinyl Chloride decision found inherent
in Section 112.

When dealing with more dangerous, life-threatening
Section 112 hazardous chemicals or carcinogens for which
an “ample” margin of safety is to be applied, EPA is
required to determine the safe exposure level and not just
a final standard with an unquantified, purportedly “am-
ple’ margin of safety. EPA should not be given more
discretion and held to a lower standard of care and ar-
ticulation when it addresses commonplace pollutants ad-
dressed by Section 109, to which a less than ample, “ade-
quate” safey margin is to be applied.* The Clean Air
Act requires EPA to make certain fundamental determi-
nations in setting standards for dangerous pollutants.
Certainly such procedures should be applied to the estab-
lishment of nationally applicable standards for the
ubiquitous but considerably less dangerous pollutants
regulated under Section 109, particularly since overly
stringent standards can result in plant shutdowns, wide-
spread unemployment and adverse health impacts found
to result from unemployment.

24 Section 109 pollutants are widespread and commonly encoun-
tered (resulting from “numerous or diverse mobile or stationary
sources”) and “may reasonably be anticipated to endanger public
health or welfare.” Section 112 hazardous air pollutants, however,
are less common but when encountered “may reasonably be antici-
pated to result an increase in mortality or an increase in serious
irreversible, or incapacitating reversible, illness.”

15

Il. BY FAILING TO DEFINE SAFE EXPOSURE LEV-
ELS FOR ITS SECTION 109 STANDARDS EPA HAS
EXCEEDED ITS STATUTORY AUTHORITY AND
PREVENTED MEANINGFUL JUDICIAL REVIEW

If, as concluded by the D.C. Circuit on three separate
occasions in the Lead and Ozone decisions and the pres-
ent PM,, decision, EPA has discretion to establish an
ambient standard without ever having to determine what
air quality level is “safe,” or what is an adequate margin
of safety, EPA can, as it proved with the PM,, stand-
ards, choose virtually any level, and its selection is es-
sentially unreviewable. EPA need only state for the
record that it reviewed the available scientific evidence,
state that its review disclosed no obvious answers, and
then select a number, any number for the final standard.
The court below gives EPA this latitude because it won’t
require EPA to identify the “safe” exposure level as a
benchmark against which to compare the standard.

Instead, the decision below announces the proposition
that the greater the scientific uncertainty, the greater
the latitude to be accorded the agency and the less artic-
ulation is required. 902 F.2d at 974, NCA App. at 28a.
In other words, the less support EPA can adduce for a
Section 109 standard, the greater the deference EPA is
to be accorded. Such deference seriously reduces, if not
eliminates, any meaningful role for the reviewing court.
Absent any indication in the record of what risks EPA
deems to be acceptable, the reviewing court has no basis
against which to evaluate EPA’s judgment.

The decision below actually excuses, and conceivably
encourages, scientific imprecision and lack of data for
governmental standard setting. If scientific uncertainty
increases agency discretion, and, in turn, judicial defer-
ence, agencies have no impetus to generate or commission
the scientific data necessary for setting standards.

Under a proper reading of Section 109, not only is
EPA required to identify both the health protective limit

16

and the margin of safety applied thereto, EPA also is
required to articulate clearly and separately the appro-
priate factors relevant to each such determination. Such
a delineation is necessary to assure that each determina-
tion is made in a rational manner with due consideration
of the different factors applicable to each and to assure
that the courts are able to discharge their review func-
tion properly. As this Court aptly pointed out:

Expert discretion is the lifeblood of the administra-
tive process, but “unless we make the requirements
for administrative action strict and demanding, ex-
pertise, the strength of modern government, can be-
come a monster which rules with no practical limits
on its discretion” (citation omitted).

Burlington Truck Lines v. United States, 371 U.S. 156,
167 (1962).

To permit EPA to speculate as to theoretical health
risks, without regard to the certain harm to the public
welfare that flows from unduly stringent standards and
without guidance as to where on the continuum of rela-
tive safety the Administrator should draw his line, as the
decision of the court below permits, would be a “sweep-
ing delegation of legislative power” that raises serious
Constitutional questions. See, A.L.A. Schechter Poultry
Corp. v. United States, 295 U.S. 495, 5389 (1935);
Panama Refining Co. v. Ryan, 293 U.S. 388 (1935).
See also Industrial Union Dep’t. AFL-CIO v. American
Petroleum Inst., 448 U.S. 607 (1980) (Plurality Opin-
ion), 671 (Rehnquist, J., concurring in the judgment).
The Court need not address this issue here, however, be-
cause the court below erred in its construction of the
basic requirements of Section 109.

This Court should clarify the requirements of Section
109 by granting this Petition and by concluding that, in
setting standards under Section 109, EPA must separ-
ately determine the safety level for the pollutant in ques-

eee DO ee Bihne eine ee

17

tion and the margin of safety it applied to that level and
for each determination articulate its rationale.
CONCLUSION

For the forgoing reasons, this Petition for a Writ of
Certiorari should be granted.

Respectfully submitted,

Of Counsel: ROBERT A. EMMETT
BARTON C, GREEN (Attorney of Record)
AMERICAN IRON AND REED SMITH SHAW & MCCLAY
STEEL INSTITUTE 1200 18th Street, N.W.

Washington, D.C. 20036
(202) 457-6144
Attorney for Petitioner
American Iron and
October 1, 1990 Steel Institute

APPENDICES

la
APPENDIX A

FINAL RULE OF THE UNITED STATES
ENVIRONMENTAL PROTECTION AGENCY

(Excerpts)

ENVIRONMENTAL PROTECTION AGENCY
40 CFR Part 50
[AD-FRL 3141-9 (a) ]

Revisions to the National Ambient Air Quality
Standards for Particulate Matter

AGENCY: Environmental Protection Agency (EPA).
ACTION: Final rule.

SUMMARY: In 1971, EPA promulgated primary and
secondary national ambient air quality standards for
particulate matter, measured as “total suspended partic-
ulate matter” or “TSP.” The primary standards were
set at 260 »g/m*, 24-hour average not to be exceeded
more than once per year, and 75 »g/m*, annual geometric
mean. The secondary standard, also measured as TSP,
was set at 150 ug/m*, 24-hour average not to be exceeded
more than once per year. In accordance with sections
108 and 109 of the Clean Air Act, EPA has reviewed and
revised the health and welfare criteria upon which these
primary and secondary particulate matter standards
were based.

On March 20, 1984 (49 FR 10408), EPA proposed
changes in the standards based on its review and revision
of the criteria. Today’s notice announces EPA’s final
decisions regarding these changes. The final decisions in-
clude: (1) replacing TSP as the indicator for particu-
late matter for the ambient standards with a new indi-

2a

cator that includes only those particles with an aerody-
namic diameter less than or equal to a nominal 10 micro-
meters (PM,,), (2) replacing the 24-hour primary TSP
standard with a 24-hour PM,, standard of 150 ,»g/m*
with no more than one expected expected exceedance per
year; (3) replacing the annual primary TSP standard
with a PM,, standard of 50 y»g/m*, expected annual
arithmetic mean; and (4) replacing the secondary TSP
standard with 24-hour and annual PM,, standards that
are identical in all respects to the primary standards.

* * * *

Table of Contents
I. Background

A. Legislative Requirements Affecting This Rule

1. The Standards

2. Related Control Requirements

Particulate Matter and Original Standards for TSP

C. Development of Revised Air Quality Criteria for
Particulate Matter

D. Review of the Standards: Development of Staff
Paper

E. Proposed Revisions to the Standards

F. Supplemental Criteria Revisions and Standards Re-
view Following Proposal

oe

II. Summary of Public Comments
A. Comments on 1984 Proposal

B. Comments on Subsequent Notice

III. Rationale for the Primary Standards
A. Pollutant Indicator
B. Averaging Time and Form of the Standards
1, 24-hour Standard
2. Annual Standard

VI.

VIL.

VIII.

3a

C. Level of the Standards
1. 24-hour standard
2. Annual Standard

Rationale for the Secondary Standards
A. Soiling and Nuisance
B. Other Welfare Effects

Federal Reference Method
A. Specific Changes to Appendix J
B. Designation of Reference Methods for PM,,

C. Technical Change to Appendix G

Summary of Salient Public Comments and Agency
Responses

A. Health Effects Criteria and Selection of the Pri-
mary Standards

1. Indicater for the Primary Standards

2. Interpretation of Community Epidemiological
Studies

3. Margin of Safety
B. Secondary Standards
1. Soiling and Nuisance
2. Visibility
C. Averaging Time and Form of the Standards
1. Expected Exceedances for the 24-hour Standard

2. Expected Arithmetic Mean for the Annual
Standard

Regulatory and Environmental Impacts
A. Regulatory Impact Analysis
B. Impact on Small Entities

Other Reviews

4a

References

Addendum I—CASAC Review and Closure of the 1982 Cri-
teria Document for Particulate Matter/Sulfur Oxides and
the 1986 Second Addendum to the Criteria Document

Addendum II—CASAC Review and Closure of the 1982
OAQPS Staff Paper for Particulate Matter and the 1986
Addendum to the Staff Paper

Addendum III—Executive Summary of the 1986 Addendum
to the Staff Paper

Part 50—National Primary and Secondary Ambient Air
Quality Standards

Appendix J—Reference Method for the Determination of
Particulate Matter as PM,, in the Atmosphere

Appendix K—Interpretation of the National Ambient Air
Quality Standards for Particulate Matter

I. Background
A. Legislative Requirements Affecting This Rule

1. The Standards

Two sections of the Clean Air Act govern the establish-
ment and revision of national ambient air quality stand-
ards (NAAQS). Section 108 (42 U.S.C. 7408) directs
the Administrator to identify pollutants which may rea-
sonably be anticipated to endanger public health or wel-
fare and to issue air quality criteria for them. These air
quality criteria are to reflect the latest scientific infor-
mation useful in indicating the kind and extent of all
identifiable effects on public health or welfare that may
be expected from the presence of a pollutant in the am-
bient air.

Section 109 (42 U.S.C. 7409) directs the Administra-
tor to propose and promulgate “primary” and “sec-
ondary” NAAQS for pollutants identified under section
108. Section 109(b)(1) defines a primary standard as
one the attainment and maintenance of which, in the
judgment of the Administrator, based on the criteria and

5a

allowing for an adequate margin of safety, is requisite
to protect the public health. A secondary standard, as
defined in section 109(b) (2), must specify a level of air
quality the attainment and maintenance of which, in the
judgment of the Administrator, based on the criteria,
is requisite to protect the public welfare from any known
or anticipated adverse effects associated with the presence
of the pollutant in the ambient air. Welfare effects
are defined in section 302(h) (42 U.S.C. 7602(h)) to
include effects on soils, water, crops, vegetation, man-
made materials, animals, wildlife, weather, visibility,
climate, damage to and deterioration of property, hazards
to transportation, and effects on economic values and on
personal comfort and well-being.

The U.S. Court of Appeals for the D.C. Circuit has
held that the requirement for an adequate margin of
safety for primary standards was intended to address
uncertainties associated with inconclusive scientific and
technical information available at the time of standard
setting. It was also intended to provide a reasenable
degree of protection against hazards that research has
not yet identified. Lead Industries Association v. EPA,
647 F.2d 1130, 1154 (D.C. Cir. 1980), cert. denied, 101
S. Ct. 621 (1980); American Petroleum Institute v.
Costle, 665 F.2d 1176, 1177 (D.C. Cir. 1981), cert.
denied, 102 S. Ct. 1737 (1982). Both kinds of uncertain-
ties are components of the risk associated with pollution
at levels below those at which human health effects can
be said to occur with reasonable scientific certainty.
Thus, by selecting primary standards that provide an
adequate margin of safety, the Administrator is seeking
not only to prevent pollution levels that have been demon-
strated to be harmful, but also to prevent lower pollutant
levels that he finds pose an unacceptable risk of harm,
even if that risk is not precisely identified as to nature
or degree.

6a

In selecting a margin of safety, EPA has considered
such factors as the nature and severity of the health
effects involved, the size of the sensitive population(s) at
risk, and the kind and degree of the uncertainties that
must be addressed. Given that the “margin of safety”
requirement by definition only comes into play where no
conclusive showing of harm exists, such factors, which
involve unknown or only partially quantitified risks, have
their inherent limits as guides to action. The selection
of any particular approach to providing an adequate mar-
gin of safety is a policy choice left specifically to the
Administrator’s judgment. Lead Industries Association
v. EPA, supra, 647 F.2d at 1161-62.

Section 109(d) of the Act (42 U.S.C. 7409(d)) re-
quires periodic review and, if appropriate, revision of
existing criteria and standards. The process by which
EPA has reviewed the original criteria and standards
for particulate matter under section 109(d) is described
in Sections I.C. and I.D. of this notice.

2. Related Control Requirements

States are primarily responsible for ensuring attain-
ment and maintenance of ambient air quality standards
once EPA has established them. Under section 110 of the
Act (42 U.S.C. 7410), States are to submit, for EPA
approval, State implementation plans (SIPs) that pro-
vide for the attainment and maintenance of such stand-
ards through control programs directed to sources of the
pollutants involved. Other Federal programs provide for
nationwide reductions in emissions of these and other air
pollutants through the Federal Motor Vehicle Control
Program under Title II of the Act (42 U.S.C. 7501 to
7534), which involves controls for automobile, truck, bus,
motorcycle, and aircraft emissions, and through the devel-
opment of New Source Performance Standards under sec-
tion 111 (42 U.S.C. 7411) and National Emission Stand-
ards for Hazardous Air Pollutants under section 112
(42 U.S.C. 7412).

|

Ta
B. Particulate Matter and Original Standards for TSP

“Particulate matter” is the generic term for a broad
class of chemically and physically diverse substances that
exist as discrete particles (liquid droplets or solids) over
a wide range of sizes. Particles originate from a variety
of stationary and mobile sources. They may be emitted
directly or formed in the atmosphere by transformations
of gaseous emissions such as sulfur oxides, nitrogen
oxides, and volatile organic substances. The chemical and
physical properties of particulate matter vary greatly
with time, region, meteorology and source category, thus
complicating the assessment of health and welfare ef-
fects. The characteristics, origins, concentrations, and
potential effects of particulate matter are discussed in
more detail in the staff paper (SP) (EPA, 1982a), in
the revised criteria document (CD) (EPA, 1982b), in
the criteria document addendum (CDA) (EPA, 1986a)
and in the staff paper addendum (SPA) (EPA, 1986b).
The executive summary of the staff paper addendum is
reprinted in Addendum III to this notice.

On April 30, 1971 (36 FR 8186), EPA promulgated
the original primary and secondary NAAQS for particu-
late matter under section 109 of the Clean Air Act. The
reference method for measuring attainment of these
standards is the “high-volume” sampler (40 CFR Part
50, Appendix B), which collects particulate matter up to
a nominal size of 25 to 45 micrometers (nm) (so-called
“total suspended particulate,” or “TSP”). Thus, TSP is
the current indicator for the particulate matter stand-
ards. The existing primary standards for particulate
matter (measured as TSP) are 260 y»g/m*, 24-hour
average not to be exceeded more than once per year, and
75 »g/m*, annual geometric mean. The secondary stand-
ard (measured as TSP) is 150 »g/m', 24-hour average
not to be exceeded more than once per year. The scien-
tific and technical bases for these standards are con-
tained in the original criteria document, Air Quality Cri-
teria for Particulate Matter (DHEW, 1969).

8a

C. Development of Revised Air Quality Criteria for
Particulate Matter

In 1976, as a result of internal Agency review and the
recommendations of a committee of EPA’s Science Ad-
visory Board, EPA decided to revise the existing criteria
document for particulate matter. Because of competing
priorities regarding revision of other criteria documents,
and because of the need to complete additional research
on particulate matter, the process was scheduled to com-
mence in 1979. With the endorsement of the Clean Air
Scientific Advisory Committee (CASAC) of EPA’s Sci-
ence Advisory Board, EPA decided to review and revise
the criteria document for particulate matter concurrently
with that for sulfur oxides and to produce a combined
particulate matter/sulfur oxides (PM/SO.) criteria doc-
ument. On October 2, 1979 (44 FR 56731), EPA an-
nounced that it was in the process of revising the criteria
document and reviewing the existing air quality stand-
ards for possible revisions.

In developing the revised criteria document, EPA has
provided a number of opportunities for review and com-
ment by organizations and individuals outside the
Agency. Three drafts of the revised particulate matter/
sulfur oxide criteria document, prepared by EPA’s En-
vironmental Criteria and Assessment Office (ECAO},
were made available for external review on April 11,
1980 (45 FR 24913), January 29, 1981 (46 FR 9746),
and October 28, 1981 (46 FR 53210). EPA received and
considered numerous and often extensive comments on
each of these drafts. CASAC held three public meetings
to review successive drafts of the document on August
20-22, 1980 (45 FR 5164, August 4, 1980), July 7-9,
1981 (46 FA 31746, June 17, 1981), and November
16-18, 1981 (46 FR 53210, October 28, 1981). These meet-
ings were open to the public and were attended by many
individuals and representatives of organizations who pro-
vided critical reviews and new information for considera-

9a

tion. In accordance with CASAC recommendations made
after the first review meeting, five additional public
meetings were held at which EPA, its consulting authors
and reviewers, and other scientifically and technically
qualified experts selected by EPA discussed the various
chapters of the draft document and suggested ways of
resolving outstanding issues (45 FR 74047, November 7,
1980; 45 FR 78224, November 25, 1980; 45 FR 76790,
November 20, 1980; 45 FR 80350, December 4, 1980;
46 FR 1775, January 7, 1981).

The comments received on the successive drafts of the
revised criteria document were considered in the final
document, issued simultaneously with the proposal of
revisions to the standards. A summary of EPA’s re-
sponses to the comments on the three external review
drafts of the documents is in the public docket (Docket
No. A-82-37). Transcripts of the three CASAC meetings
are also in the docket. In accordance with its established
procedures, CASAC prepared a “closure” memorandum
to the Administrator indicating its satisfaction with the
final draft (December, 1981) of the criteria document
and outlining key issues and recommendations. The
closure memorandum, dated January 29, 1982, stated
that the EPA office that prepared this document was
“responsive to Committee advice as well as to comments
provided by the general public . . .” The closure memo-
randum further stated that the criteria document “ful-
fills the requirements set forth in section 108 of the Clean
Air Act, which requires that the criteria document ‘shall
accurately reflect the latest scientific knowledge useful
in indicating the kind and extent of all identifiable effects
on public health or welfare’ from sulfur oxides and par-
ticulates in the ambient air.” The CASAC closure memo-
randum on the criteria document is reprinted in its en-
tirety in Addendum I to this notice. Following closure,
minor technical and editorial refinements were made to
the criteria document for printing (EPA, 1982b).

10a

A number of scientific and technical issues were raised
during the public review process. With respect to the
particulate matter portions of the criteria document, the
major issues included the relationship among various
measures of particulate matter air quality, the implica-
tions of particle deposition and other studies for selecting
a particulate matter indicator, and the development and
application of criteria for deciding which epidemiological
studies are most appropriate for use in revising air qual-
ity standards. A summary of these and other major scien-
tifie issues, as well as CASAC’s conclusions, is included
in the closure memorandum on the criteria document
(Addendum I).

D. Review of the Standards: Development of Staff Paper

In the evolving process of revising the national am-
bient air quality standards, EPA has found it useful to
prepare a document that helps bridge the gap between
the scientific review of health and welfare effects con-
tained in the criteria document and the judgments re-
quired of the Administrator in setting ambient standards.
This document, known as the staff paper, has become an
important element in the standards review process, pro-
viding an opportunity for public comment on proposed
staff recommendations before they are presented to the
Administrator.

In the spring of 1981, EPA’s Office of Air Quality
Planning and Standards (OAQPS) prepared the first
draft of the staff paper, Review of the National Am-
bient Air Quality Standards for Particulate Matter: As-
sessment of Scientific and Technical Information. This
draft staff paper, based on the then existent draft of tne
revised criteria document, evaluated and interpreted the
available scientific and technical infprmation most rele-
vant to the review of the air quality standards for par-
ticulate matter and presented staff recommendations on
alternative approaches to revising the standards. This

lla

and a second draft of the paper were reviewed at two
CASAC meetings on July 7-9, 1981 (46 FR 31746, June
17, 1981), and November 16-18, 1981 (46 FR 538210,
October 28, 1981). Numerous written and oral comments
were received on the drafts from CASAC, representatives
of organizations, individual scientists, and other inter-
ested members of the public. A summary of major re-
visions made in response to comments on the first draft
is contained in an October 31, 1981 letter to CASAC
(Padgett, 1981). Following the second CASAC meeting,
the staff made further revisions in response to comments
and prepared an executive summary that was received by
CASAC members before preparation of the closure memo-
randum on the staff paper. In January, 1982, EPA re-
leased the final OAQPS staff paper (EPA, 1982a), which
reflects the various suggestions made by CASAC and
members of the public. The January 29, 1982, CASAC
closure memorandum states that the staff paper “has
been modified in accordance with recommendations made
by CASAC,” is consistent with the criteria document, and
provides the Administrator “with the kind and amount of
technical guidance that will be needed to make appropri-
ate revisions to the standard.” This closure memoran-
dum is reprinted in Addendum II to this notice.

A number of major issues were raised during the pub-
lic review process. The more important issues are out-
lined below.

1. Substantial discussion concerned the maximum size
of particles (or particle size fraction) to be used in
measuring particulate matter for regulatory purposes.
Some groups favored retaining TSP as an indicator;
others called for alternative size-specific standards with
nominal “size cuts” (“D,,.”; see discussion in Section
III.A.) of 15 pm, 10 G6mm, 5-7 G6mm, and 2.5 G6mm.
After CASAC closure on the staff paper and criteria doc-
ument, comments were received from one group favoring
a so-called “D,” of 10um (approximately equivalent to a
nominal size cut [D,.] of 6 um).

12a

2. Much attention was focused on selecting the level
of the primary standards and on the question of which
health effects studies were most appropriate for this pur-
pose. Significant criticisms were received on the major
epidemiological studies of particulate matter exposures,
highlighting their limitations for use in standard setting.
In a number of comments, specific suggestions for stand-
ards were made.

3. With respect to secondary standards, most attention
focused on the possible need for a fine [=2.5 G6m) par-
ticle standard designed to protect visibility.

These and other major issues are discussed more fully
in the executive summary of the staff paper and in later
sections of this notice. CASAC’s discussion of these is-
sues and its recommendations are contained in the closure
memorandum on the staff paper (Addendum II).

E. Proposed Revisions to the Standards

On March 20, 1984 (49 FR 10408) EPA proposed a
number of revisions to the primary and secondary par-
ticulate matter standards. The proposed revisions, based
on the revised criteria, included:

(1) Replacing TSP as the indicator for particulate
matter for the primary standards with a new indicator
that includes only those particles with an aerodynamic
diameter less than or equal to a nominal 10 micrometers
(PM,,);

(2) Changing the level of the 24-hour primary stand-
ard to a value to be selected from a range of 150 to 250
pg/m*® and replacing the deterministic form of the stand-
ard, which permitted not more than one observed ex-
ceedance of the standard per year, with a statistical form
that would permit one expected exceedance per year;

(8) Changing the level of the annual primary stand-
ard to a value to be selected from a range of 50 to 65
ypg/m*, and changing the form from an annual geometric
mean to an expected annual arithmetic mean; and

13a

(4) Replacing the current 24-hour secondary TSP
standard by an annual TSP standard selected from a
range of 70 to 90 yug/m*, expected annual arithmetic
mean.

The Administrator expressed an inclination to select
the primary standards from the lower portions of the
above ranges. With respect to the secondary standards,
the Administrator was inclined to select the final stand-
ard from the upper portion of the range, but also called
for comment on the alternative of using PM,, as the
particulate matter indicator for the secondary standards
and making the secondary standards identical in all re-
spects to the primary standards. The proposal notice sets
forth the rationale for these and other proposed revisions
of the particulate matter NAAQS and background infor-
mation related to the proposal.

F. Supplemental Criteria Revisions and Standards Re-
view Following Proposal

Following publication of the proposal, EPA held a pub-
lice meeting in Washington, D.C. on April 30, 1984 to
receive comments on the proposed standards revisions.
A transcript of the meeting has been placed in the public
docket (Docket No. A-82-37). After the close of the orig-
inal public comment period (June 5, 1985), the CASAC
met on December 16-17, 1985 to review the proposal and
to discuss the relevance of certain new scientific studies
on the health effects of particulate matter that had
emerged since the Committee completed its review of the
criteria document and staff paper in January, 1982. A
transcript of this meeting is also available in the Docket.
Based on its preliminary review of these new studies, the
Committee recommended that the Agency prepare sepa-
rate addenda to the criteria document and staff paper for
the purpose of evaluating the relevant new studies and
discussing their potential implications for standard-
setting. The Agency announced its acceptance of these

14a

recommendations on April 1, 1986 (51 FR 11058). On
July 3, 1986, EPA announced (51 FR 24392) the avail-
ability of the external review draft document entitled:
Second Addendum to Air Quality Criteria for Particulate
Matter and Sulfur Oxides (1982): Assessment of Newly
Available Health Effects Information. At the same time,
the Agency announced a supplementary comment period
on the March 20, 1984 proposal to provide the public an
opportunity to comment on the implications of the new
studies and addenda for the final standards. On Septem-
ber 16, 1986, EPA announced (51 FR 32878) the avail-
ability of the draft staff paper addendum entitled Review
of the National Ambient Air Quality Standards for Par-
ticulate Matter: Updated Assessment of Scientific and
Technical Information. CASAC held a public meeting on
October 15-16, 1986 to review both the criteria document
addendum and the staff paper addendum. At this meet-
ing, CASAC members as well as representatives of sev-
eral organizations, provided critical review of both EPA
documents. A transcript of the CASAC meeting has been
placed in the public docket (A-82-37).

The CASAC sent a closure letter on the criteria docu-
ment addendum to the Administrator dated December 15,
1986, which concludes “that this 1986 Addendum along
with the 1982 Criteria Document, previously reviewed by
CASAC, represent a scientifically balanced and defensible
summary of the extensive scientific literature on these
pollutants” (Lippman, 1986b). The closure letter on the
criteria document addendum is reprinted in Addendum I
of this notice. The Committee sent their closure letter
on the staff paper addendum to the Administrator dated
December 16, 1986, stating “The Committee believes that
this document provides you with the kind and amount
of technical guidance that will be needed to make appro-
priate revisions to the standards” (Lippman, 1986c).
The closure letter on the staff paper addendum, which
also discusses major issues addressed by the CASAC and
the Committee’s recommendations concerning these issues,

15a

is reprinted in Addendum II to this notice. The final
addenda to the criteria document (EPA, 1986a) and the
staff paper (EPA, 1986b), which include revisions to
reflect comments from CASAC and the public, are avail-
able from the address listed above. Where there are dif-
ferences between the 1982 Criteria Document and staff
paper and the more recent addenda, the addenda super-
sede the earlier document. The executive summary of the
staff paper addendum is reprinted in Addendum III of
this notice.

II. Summary of Public Comments

The following discussion summarizes in general terms
the comments received from the public and from govern-
mental agencies regarding the proposed revisions to the
indicator, form, averaging times, and levels of the pri-
mary and secondary standards. Many of these comments
had been made previously by the public during public
deliberations on drafts of the criteria document and staff
paper and were reviewed and addressed by EPA in re
visions to those documents. Salient comments on all as-
pects of the proposal and Agency responses to those
comments are summarized by category in Section VI of
this notice. A more detailed description of individual
comments and Agency responses has been entered in the
public docket (No. A-82-37).

A. Comments on 1984 Proposal

Extensive written comments were received during the
original comment period on the proposal, which closed
June 5, 1985. Of some 312 written submissions, 153 were
provided by individual industrial concerns or industry
groups, 93 by State, local, and Federal government agen-
cies and organizations, 32 by environmental and public
interest groups, and 34 by individual private citizens.'

1This numerical distribution of comments in each category
should be compared with caution. For example, the American Iron

l6a

The comments on the key elements of the proposed stand-
ards are summarized below:

(1) Indicator for the Primary Standard: The over-
whelming majority of the comments received on this issue
favcred a size-selective indicator for the PM standard.
Of the 147 written comments received on this issue, 108
supported the PM,, indicator proposed by the Agency.
Most of the remaining comments were in support of al-
ternative smaller particle size indicators including PM,
(28 comments) and PM,., (8 comments). The principal
support for PM, came from mining and related indus-
tries.

(2) Levels of the Primary Standards: Comments on
the proposed levels for the two primary standards were
more polarized than those on the indicator. Most indus-
try comments favored selecting the level of the standards
at the upper end of the proposed ranges or above, while
most of the remaining commenters favored standard
levels at the lower bound of the ranges, and in some cases
lower. Additional comments from individual citizens, en-
vironmental groups, and government agencies urged that
the level of protection afforded by the current particulate
matter standards be maintained or strengthened.

* & * *

B. Comments on Subsequent Notice

As discussed earlier in this notice, EPA announced an
additional public comment period on July 3, 1986 to ad-
dress the implications of new scientific studies on the
health effects of particulate matter [51 FR 24392]. Ap-
proximately 20 additional written submissions were re-
ceived by the close of this comment period on November

and Steel Institute and the American Petroleum Institute submitted
comments on behalf of 63 and 230 individual companies respectively,
in lieu of having each of their member companies send separate
comments. Similarly, comments from interest groups such as
NRDC represent the views of a number of individuals.

Cae eae Aon A edt

ithe inden Pe ol ea

~ Nts

= aca Ab NR ANA em CA eS me IA OY ay n

17a

17, 1986, 17 of which were provided on behalf of indus-
try groups or companies, 2 from environmental groups,
and 1 from a state agency. Much of the material related
to evaluations of specific studies and their treatment in
the staff paper addendum. The industry comments, which
included submissions from consulting scientists and ana-
lysts, generally found that the new studies suffered from
deficiencies that preclude placing much weight on them
in standard setting. These commenters concluded that
their original recommendations (summarized above)
with respect to the standards remained valid. The two
environmental groups felt that the findings in these new
studies necessitated standards below the lower bounds of

the proposed ranges.

III. Rationale for the Primary Standards

In selecting primary standards for particulate matter,
the Administrator must specify: (1) the particle size
fraction that is to be used as an indicator of particulate
pollution; (2) the appropriate averaging times and
form(s) of the standards; and (3) the numerical levels
of the standards. These specifications must be considered
collectively in evaluating the margin of safety afforded by
particulate matter standards. Based on the assessments
of relevant scientific and technical information in the
criteria document and addendum, the staff paper and
staff paper addendum (hereinafter “SP” and “SPA,”
respectively) outline a number of key factors to be con-
sidered in making decisions in each of these areas (SP,
Section VI; SPA, Section IV). Both the staff and
CASAC made recommendations to focus consideration on
a discrete range of options. In most respects, the Ad-
ministrator has adopted the recommendations and sup-
porting reasons contained in the staff paper and adden-
dum and the CASAC closure statements (Friedlander,
1982; Lippman, 1986c). Rather than reiterating those
discussions at length, the following discussion of the
standards revisions focuses primarily on those considera-

18a

tions that were most influential in the Administrator’s
selection of particular options, or that differ in some re-
spect from considerations that influenced the staff and/or
CASAC recommendations.

A. Pollutant Indicator

Based on the staff assessment of the available scien-
tific information, EPA concludes that (1) a separate
particulate matter standard (as opposed to a combination
standard for particulate matter and SO.) remains a
reasonable public health policy choice, and (2) given cur-
rent scientific knowledge and uncertainties, a size-specific
(rather than chemical-specific) indicator should be used.
In assessing the information in the criteria document, the
staff reached several conclusions summarized here (see
SP, pp. 71-75) :

(1) Health risks posed by inhaled particles are influ-
enced both by the penetration and deposition of particles
in the various regions of the respiratory tract, and by
the biological responses to these deposited materials.
Smaller particles penetrate furthest in the respiratory
tract. The largest particles are deposited in the extra-
thoracic (head) region with somewhat smaller particles
depositing in the tracheobronchial region. Still smaller
particles can reach the deepest portion of the lung, the
alveolar region.

(2) The risks of adverse health effects associated with
deposition of typical ambient fine and coarse particles?
in the thorax (tracheobronchial and alveolar regions of
the respiratory tract) are markedly greater than those
associated with deposition in the extrathoracic (head)
region. Maximum particle penetration to the thoracic re-
gion occurs during oronasal or mouth breathing. .

(3) The size-specific indicator for primary standards
should represent those particles small enough to penetrate

2 Particles in ambient air usually occur in two somewhat over-
lapping size distributions, fine (diameter less than 2.5u.m) and
coarse (diameter larger than 2.5 pm). The two size fractions tend
to have different origins and composition (SP, Appendix D).

ON ON. wr coe tiene a! tell

ee Senne ks ee at © eee

19a

to the thoracic region (both the tracheobronchial and
alveolar regions). The risks of adverse health effects
from extrathoracic deposition of typical ambient par-
ticulate matter are sufficiently low that particles deposit-
ing only in that region can safely be excluded from the
indicator.

Considering these conclusions together with other infor-
mation on air quality composition, respiratory tract depo-
sition and health effects, the need to provide protection
for sensitive individuals who may breathe by mouth and/
or oronasally, and the similar convention on particles
penetrating the thoracic region recently adopted by the
International Standards Organization (ISO, 1981), the
staff recommended that the size-specific indicator include
particles of diameters less than or equal to a nominal 10
um “cut point.’”’* The factors considered in the original
staff recommendations for a 10 um cut point are outlined
in the staff paper (SP, pp. 75-79). This indicator is re-
ferred to as “thoracic particles” (TP) in the 1982 staff
paper, is now generally referred to as “PM,,.” Such an
indicator is conservative with respect to health protection
in that it includes all of the particles small enough to
penetrate to the sensitive alveolar region, and includes
approximately the same proportion of larger particles as
would be expected to reach the tracheobronchial region.
It places substantially greater emphasis on controlling
smaller particles than does a TSP indicator, but does not
completely exclude larger particles from all control.

The assessment of more recent information on respira-
tory tract deposition in the criteria document and staff

3The more precise term is 50% cut point or 50% diameter
(D,,). This is the aerodynamic particle diameter for which the
efficiency of particle collection is 50%. Larger particles are not
excluded altogether, but are collected with substantially decreasing
efficiency and smaller particles are collected with increasing (up to
100%) efficiency. Ambient samples with this cut point provide a
reliable estimate of the total mass of suspended particulate matter
of aerodynamic size less than or equal to 10ym. See additional dis-
cussion regarding the Federal Reference Method in section V below
and in the accompanying notice revising 40 CFR Part 53.

20a

paper addenda reinforces the conclusions reached in the
original staff asesssment. In particular, the staff paper
addendum found that: (1) the recent data do not pro-
vide support for an indicator that excludes all particles
larger than 10 »m in diameter;* (2) the analysis used
to support an alternative indicator with a nominal size
cut of 6 G6mm (Swift and Proctor, 1982) significantly
underestimated thoracic deposition of particles larger
than 6 »m in diameter under natural breathing condi-
tions; (3) the PM,, indicator generally includes a simi-
lar or larger fraction of the range of particles that can
deposit in the tracheobronchial region, although it ap-
pears to be somewhat less conservative in this regard
than previously thought with respect to large (G6=10
um) particle deposition under conditions of natural
mouthbreathing; and (4) the studies of tracheobronchial
deposition generally involved adult subjects; recent in-
formation indicating even greater tracheobronchial depo-
sition of particles in children than in adults provides an
additional reason for an indicator that includes particles
capable of penetration of the tracheobronchial region
(SPA, p. 36). Consideration of these and the earlier con-
clusions led the staff to reaffirm its recommendation for
a PM,, indicator (SPA, pp. 36-37). The CASAC also
restated its recommendation for PM,, in its review of the
proposal and the closure letter to the Administrator
(Lippmann, 1986 a, ¢c).

The Administrator accepts the recommendations of the
staff and CASAC and their underlying rationale and has
decided to replace TSP as the particle indicator for the
primary standards with a new indicator that includes
only those particules less than a nominal 10 »m in di-
ameter, as specified in the Federal Reference Method
(Appendix J to 40 CFR Part 50) being promulgated to-

{
4 The American Mining Congress (AMC, 1982) had recommended
such an indicator, with a “D,” of 10,m. EPA estimated that the
“D,,.” of this indicator would be 6 ym.

21a

day. In defining the standards for particulate matter,
this new indicator is termed PM...

* * * o

C. Level of the Standards

The original staff paper and CASAC recommendations
set forth a framework for determining the levels for the
proposed particulate matter standards that would pro-
tect public health with an adequate margin of safety.
The discussion that follows relies heavily on that frame-
work and on the supporting material in the staff paper
and its addendum as well as the CASAC closure letters.
The essential steps in this framework are summarized
here.

1. Assessment of the quantitative epidemiological
studies.

The criteria document and its addendum identify a
small number of community epidemiological studies that
are useful in determining concentrations at which par-
ticulate matter is likely to affect public health. The staff
used these quantitative studies to examine concentration-
response relationships and to develop numerical “ranges
of interest” for possible PM,,, standards.

A number of uncertainties associated with use of these
studies must be considered in selecting an appropriate
margin of safety. As discussed in the staff paper and
the criteria document, and the addenda to those docu-
ments, epidemiological studies are generally limited in
sensitivity and subject to inherent difficulties involving
confounding variables. Moreover, many of the quantita-
tive studies were conducted in times and places where
pollutant composition may have varied considerably from
current U.S. atmospheres. Most also have used British
Smoke * or TSP as particle indicators. None of the pub-

5 British Sméke (BS) is a pseudo-mass indicator related to small
particle (aerodynamic diameter less than a nominal 4.5 ,m) dark-
ness. This particulate matter indictaor was widely used in British
and other European studies. See the criteria document for a more
detailed treatment of BS (CD, pp. 1-88 to 1-90 and 14-8 to 14-11).

22a

lished studies used the proposed PM,, indicator. Thus,
assumptions must be used to convert the various results
to common (PM,,) units (SP, pp. 96-100; SPA pp. 9-11).

2. Identification of additional margin of safety con-
siderations.

The criteria document identifies an additional substan-
tial body of scientific literature that, while not providing
reliable concentration-response relationships for ambient
exposures, does provide important qualitative insights
into the health risks associated with human exposure to
particles. This literature includes both quantitative and
qualitative epidemiological studies, controlled human ex-
posure experiments, and animal toxicological studies.
The staff assessed this literature to identify additional
factors and uncertainties that should be considered in
selecting the most appropriate margin of safety (SP, pp.
100-101; 107-111, SPA pp. 52-53; 59).

3. Selection of the levels that might be considered to
provide an adequate margin of safety.

The intent of the margin of safety requirement was to
direct the Administrator to set air quality standards at
pollution levels below those at which adverse health ef-
fects have been found or might be expected to occur in
sensitive groups. Experience with the requirement has
shown that the scientific data are often so inconclusive
that is is difficult to identify with confidence the lowest
pollution level at which an adverse effect will occur.
Moreover, in cases such as the present one, the evidence
suggests that there is a continuum of effects, with the
risk, incidence, or severity of harm decreasing, but not
necessarily vanishing, as the level of pollution is de-
creased.

In the absence of clearly identified thresholds for health
effects, the selection of a standard that provides an ade-
quate margin of safety requires an exercise of informed
judgment by the Administrator. The level selected will
depend on the expected incidence and severity of the po-
tential effects and on the size of the population at risk,

eS

23a

as well as on the degree of scientific certainty that the
effects will in fact occur at any given level of pollution.
For example, if a suspected but uncertain health effect is
severe and the size of the population at risk is large, a
more cautious approach will be appropriate than would
be if the effect were less troubling or the exposed popula-
tion smaller.

EPA staff originally recommended a range of potential
standards for the Administrator’s consideration (SP, pp.
111-114). The recommended range was below the levels
at which the staff, with the concurrence of CASAC, had
concluded from the available data that adverse health
effects were “likely,” but in the domain where the data
suggested that such effects were “possible.” The Admin-
istrator proposed refined ranges of standard levels that
were based on the original staff and CASAC recommen-
dations. After consideration of the new scientific evi-
dence contained in the criteria document addendum, the
staff revised its recommendations for ranges of stand-
ards (SPA, pp. 60-62). The Administrator has consid-
ered the revised assessments and the recommendations
of CASAC (Lippmann, 1986b) in making his final de-
cision on the standard levels. The rationales for the
levels of the 24-hour and annual standards are presented
below.

1. 24-Hour Standard

The revised staff assessment of the short-term epidemi-
ological data is summarized in Table 1; particulate mat-
ter levels are expressed in both the original (British
Smoke [“BS”] or TSP) and PM,, units. The “effects
likely” row in Table 1 denotes concentration ranges de-
rived from the criteria document and its addendum at or
above which a consensus judgment suggests greatest cer-
tainty that the effects studied would occur, at least under
the conditions that occurred in the original studies. In
the “effects possible” range, the staff found credible scien-
tific evidence suggesting the existence of adverse health
effects in sensitive populations, but substantial uncer-
tainty exists regarding the conclusions to be drawn from
such evidence.

24a

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26a

The data do not provide evidence of clear thresholds in
exposed populations. Instead, they suggest a continuum
of response for a given number of exposed individuals
with both the likelihood (risk) of any effects occurring
and the extent (incidence and severity) of any potential
effect decreasing with concentration. This is particularly
true for the statistical analyses of daily mortality in
London. Substantial agreement exists that wintertime
pollution episodes produced premature mortality in elderly
and ill populations, but the range and nature of associa-
tion provide no clear basis for distinguishing any par-
ticular lowest “effects likely” levels or for defining a con-
centration below which no association remains. The re-
cent lung function studies in children also provide
evidence of effects at concentrations in the range listed in
Table 1, but the relationships are not certain enough to
derive “effects likely” levels for PM,,. The lung function
studies do, however, suggest levels below which detectable
functional changes are unlikely to occur in exposed popu-
lations. Following CASAC recommendations, the staff
used the combined range listed in the “effects possible”
row as a starting point for developing alternative stand-
ards.

The original range proposed by the Administrator,
drawn from the 1982 staff analysis, was 150 to 250 yug/
m’ PM,,, 24-hour average with no more than one expected
exceedance per year. The lower bound of this range was
derived from the original assessment of the London mor-
tality studies. As a result of its updated assessment of
reanalyses of the London mortality and more recent U.S.
morbidity studies, the staff reduced the level of the lower
bound of the range of interest to 140 »g/m* (SPA, 51),
while noting that the difference between it and original
lower bound (150 yg/m*) is within the range of un-
certainty associated with converting the morbidity study
results from TSP to PM,.,. -

As indicated in Table 1, the study of Lawther et al.
(1970) judged to provide evidence that health effects are

a

:
i

27a

likely at particulate matter concentrations above 250 pg/
m* (as BS). The effects observed in this study (related
to aggravation of bronchitis) are of concern both because
of their immediate impact and because of the potential
for inducing longer-term deterioration of health status in
a significant sensitive group. There were approximately
G.5 million bronchitics in the U.S. in 1970 (DHEW,
1973). Based on the uncertain conversion between smoke
and PM,, outlined in Table 1, the lowest “effects likely”
level derived from the Lawther study (259 »pg/m* as BS)
should be in the range of 250 to 350 pg/m’*, in PM,, units.

The assessment of this study formed the basis for the
upper bound of the range of PM,, standards proposed by
the Administrator in 1984. Considering this study alone,
a PM,, standard of 250 »g/m* might appear to contain
some margin of safety, even for the sensitive bronchitics
studied, because it incorporates a conservative British
Smoke/PM,, conversion factor and because of differences
between exposure conditions in the British study and cur-
rent U.S. air quality (SP, pp. 100-101). Because bron-
chitics are identified as a group particularly sensitive to
particulate pollution, a standard of 250 »pg/m* (as PM,,)
also might provide some margin of safety for other, less
sensitive, groups. Nevertheless, this study of bronchitics
in London has inherent limitations in sensitivity that pre-
clude derivation of unequivocal “effects of thresholds” at
250 »g/m* as BS, and by extension PM,,. The criteria
document notes that associations between pollution and
health status persisted at lower BS concentrations in
selected, more sensitive individuals. Although the lead
author of the study object’ to attaching any importance
to these latter findings (Lawther, 1986), EPA, with
CASAC concurrence, finds no basis for asserting that this
study demonstrates a population threshold at 250 p»pg/m’*.

In evaluating the margin of safety for a 24-hour stand-
ard, it is also important to consider the London mortality
studies. A standard at the upper portion of the proposed

28a

range (250 ug/m*) would be well below the levels (500
to 1000 »g/m* as BS) of the historical London episodes
in which the scientific consensus indicates that pollution
was responsible for excess mortality (CD, Table 14-7).
The portions of the population at greatest risk of pre-
mature mortality associated with particulate matter ex-
posures in such episodes include the elderly and persons
with pre-existing respiratory or cardiac disease. Although
the extent of life shortening (days, weeks, or years) can-
not be specified, the seriousness of this effect strongly
justifies a margin of safety for it (below the consensus
effects levels) that is larger than that warranted for the
effects on bronchitics.

The staff assessment of the several reanalyses of Lon-
don mortality suggests, however, that the risk of pre-
mature mortality to sensitive individuals extends to
concentrations substantially lower than those which oc-
curred in the “episodes.” The more recent analyses
(Mazumdar et al., 1982; Ostro, 1984; Shumway et al.,
1983) provide no objective support for a population
threshold below which such a risk no longer exists. Al-
though the risk to individuals may be small at concentra-
tions of 250 »g/m* and below, the number of people ex-
posed to lower concentrations given current U.S. levels is
substantially larger than the number exposed to higher
levels (SPA, Table 2-1). The increased number of indi-
viduals exposed increases the risk that effects will occur
in the total population exposed.

Differences in the composition of particles and gases
among U.S. cities and between current conditions in the
U.S. and those in London at the time the mortality and
morbidity data were gathered add to the complexity of
assessing the risk associated with particulate matter in
the U.S. In the case of the mortality studies, however,
the staff found that at least one of the more recent studies
(Ozkaynak and Spengler, 1985) provides qualitative sup-
port for an association between daily mortality and par-

VO Th nd Myre aide ence erwes Cte ahs

7
:
t
:
4
:
j
;

29a

ticle concentrations in nearly contemporary U.S. atmos-
pheres (SPA, pp. 48-44).

The 1982 assessment of the mortality studies and re-
lated factors prompted the Administrator to consider
standard levels that extended from 250 »g/m* down to
the lower bound of the original staff range of interest
(150 »g/m*) and even lower. The more recent analyses
of the London mortality data provide additional evidence
that serious adverse health effects may occur at particu-
late concentrations below 250 »g/m*. These analyses have
addressed a number of the uncertainties associated with
the earlier studies, and have reinforced the Adminis-
trator’s concern that a 24-hour standard at the upper end
of the proposed range may not provide an adequate mar-
gin of safety. However, given the uncertainties in con-
verting from BS to PM,, measurements, particularly at
lower concentrations, and the possible differences in par-
ticulate composition between London at the time the data
were gathered and the contemporary U.S., it is difficult
to use these studies to set a precise level for a PM,,
standard (SPA, pp. 49-51).

Given these difficulties, it is important to examine con-
temporary studies that utilize gravimetric measurements
of particulate concentrations. The staff found the studies
of Dockery et al. (1982) and Dassen et al. (1986) to be
particularly useful. The Dockery study observed physio-
logically small but statistically significant decreases in
lung function in a group of children exposed to peak
PM,, levels of 140-250 »g/m*. The decrements persisted
for 2-3 weeks following the exposures. The study also
suggested the possibilty of larger responses in a subset
of the children, including those with existing respiratory
symptoms. The Dassen study recorded similar decrements
in children in the Netherlands following exposure to PM,,
levels estimated at 200 to 250 ug/m*, but no observable
effects two days after exposure to PM,, levels estimated
at 125 »g/m*. The particle composition, at least in the

30a

Dockery study, is more representative of contemporary
U.S. cities and the associated aerometry provides a more
reliable estimate of PM,, levels than do the measurements
used in the London studies. It is reasonable to expect
that the effects observed (small reversible reductions in
lung function in children) are, in most cases, more sen-
sitive to air pollution than those observed in the London
studies. These effects are, of themselves, of uncertain
significance to health, but might be associated with ag-
gravation of respiratory symptoms in children with pre-
existing illness (SPA, p. 47). Long-term examination of
respiratory health in the same community studied by
Dockery et al. (1982) suggests that the children in that
community have a higher incidence of respiratory illness
and symptoms than children in communities with lower
particle levels, but the data show no evidence for any
persistent reduction in lung function (Ware et al., 1986).
Uncertainties with respect to the effects of other pollut-
tants (e.g., SO.), the consistency of the changes, and ex-
posures preclude specifying unequivocal “effects likely”
levels based on this study. The staff assessment therefore
suggests that short-term lung function effects in children
are possible across a range of 140-250 »g/m* or more as
PM,, (SPA, p. 50).

In making a decision on a final standard level, the
Administrator also considered information from the more
qualitative studies of PM assessed by the staff (SP, pp.
101-103; SPA, pp. 52-53). These suggest increased risks
for sensitive groups (asthmatics) and risks of potential
effects (morbidity in adults) not demonstrated in the
more qualitative epidemiological literature. The quali-
tative studies do not provide clear information on effects
levels, but do justify consideration of effects of particu-
late matter that have not been sufficiently investigated.

Based on the scientific assessment at the time, the Ad-
ministrator in 1984 expressed an inclination to select a
24-hour level from the lower portion of the proposed

3la

range of 150-250 »g/m*. The present Administrator finds
that the updated scientific assessment supports the origi-
nal inclination and, if anything, suggests an even wider
margin of safety is warranted. The recent analyses of
daily mortality are of particular concern in this regard.
The Administrator has, therefore, decided to set the final
standard at the extreme lower bound of the range origi-
nally proposed; that is, at 150 »g/m*. This standard pro-
vides a substantial margin of safety below the levels at
which there is a scientific consensus that particulate mat-
ter causes premature mortality and aggravation of bron-
chitis. Such a margin is necessary because of the serious-
ness of these effects and because of the recent analyses of
daily mortality that suggest adverse effects may occur
at particulate matter levels well below the consensus
levels. The standard is in the lower portion of the range
where sensitive, reversible physiological responses of un-
certain health significance are possibly, but not definitely,
observed in children. Using a conservative assessment of
lung function/particle relationship from Dockery et al.,
a change in concentration from background levels (~20
pg/m*) to 150 »zg/m* would produce lung function
changes of at most 10 to 15% in less than 5% of ex-
posed children (SPA, p. 48). Based on the results of
Dassen et al. (1986), it appears unlikely that any func-
tional changes would be detected one or two days follow-
ing such exposures (SPA, p. 50). Thus, the maximum
likely changes in lung function appear to present little
risk of significant adverse responses. Standards set at a
somewhat higher level would, however, present an un-
acceptable risk of premature mortality and allow the pos-
sibility of more significant functional changes. Further-
more, a standard level of 150 »g/m* is fully consistent
with the recommendations of CASAC on the 24-hour
standard (Lippman, 1986c).

2. Annual Standard

The updated staff assessment of important long-term
epidemiological data is summarized in Table 2. Long-

32a

term epidemiological studies are subject to additional con-
founding variables that reduce their sensitivity and make
their interpretation more difficult than that of short-term
studies. The “effects likely” levels are derived from the
criteria document, but again, no clear thresholds can be
identified for all effects categories. Evidence exists of
effects at lower levels—the “effects possible levels”—but
the evidence is inconclusive and effects are difficult to
detect in the available epidemiological studies.

33a

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34a

Based on a recent assessment of PM,,/TSP ratios in
areas with elevated TSP levels, the updated staff assess-
ment revised the “effects likely” levels from the Ferris
et al. (1973) study to 80 to 90 »g/m* as PM,, (SPA, p.
58). Because of limitations in sampling duration as well
as the conversion to PM,,, this estimate is particularly
uncertain. As indicated in the table, effects are possible
at lower concentrations. Of greatest concern is the pos-
sibility of long-term deterioration of the respiratory sys-
tem in exposed populations, the potential for which is in-
dicated by lung function (mechanical pulmonary) changes
and increased incidence of respiratory disease. One set
of studies (Ferris et al., 1973, 1976) provides some evi-
dence for a “no observed effects” level for these effects
at or below 60 to 65 »g/m* (130 »pg/m* as TSP) while
another study (Bouhuys et al., 1978), suggests some pos-
sibility of symptomatic responses in adults at long-term
median levels at or below about 50 to 55 »g/m* as PM...
The importance of these symptomatic responses, which
were unaccompanied by lung function changes, to long-
term respiratory health is unclear.

The most important recent study of long-term effects is
an ongoing examination of six U.S. cities (Ware et al.,
1986). The study indicates the possibility of increased
respiratory symptoms and illnesses in children at multi-
year levels across a range of 40 to over 58 »g/m* as PM.,,,
but found no evidence of reduced lung function at such
concentrations. This study did not find similar gradients
in symptoms and illness within some of the cities, which
had somewhat smaller localized pollution gradients. The
results of a separate series of studies of long and in-
termediate term (2 to 6 weeks) exposures in a number of
U.S. metropolitan areas (Ostro, 1987 ; Hausman et al.,
1984) are more supportive of the possibility of effects
within cities (respiratory related activity restrictions in
adults) at comparable U.S. exposure levels. The results
of these more recent studies are generally consistent with
the earlier U.S. studies listed in Table 2 (SPA, 57). In

en dt ee eet

lee na ‘etauaintndls

35a

particular, the finding of symptomatic responses in chil-
dren with no change in lung function (Ware et al., 1986)
is consistent with similar findings in adults (Bouhuys et
al., 1973) at estimated long-term PM,, levels down to 50
»g/m*. However, the information available to support
the existence of significant adverse effects at annual
PM,, levels below 50 »g/m*—especially when 24-hour
levels are maintained below 150 »g/m*—is quite limited
and uncertain.

Because of the uncertainties in (SP, pp. 104-110; SPA,
54-59), as well as the limited scope and number of, these
long-term quantitative studies, it is particularly impor-
tant to examine the results of qualitative data from a
number of epidemiological, animal, and ambient particle
composition studies when evaluating what constitutes an
adequate margin of safety for an annual standard. These
studies justify concern for serious effects not directly
evaluated in the studies listed in Table 2. Such effects
include damage to lung tissues contributing to chronic
respiratory disease, cancer, and premature mortality
(SP, pp. 109-111). Substantial segments of the popula-
tion may be susceptible to one or more of these effects
(SP, p. 46). Although the qualitative data do not pro-
vide evidence for major risks of these effects at current
annual particulate matter levels in most U.S. cities, the
Administrator believes that the seriousness of the poten-
tial effects and the large population at risk warrant cau-
tion in setting the standard.

Based on the then current scientific assessment, the
Administrator proposed in 1984 to select the annual
standard level from a range of 50 to 65 »g/m*. In the
proposal, the Administrator favored a standard in the
lower portion of the range. The more recent evidence,
although subject to substantial uncertainty, serves to re-
inforce this inclination. In light of the updated assess-
ment and in accordance with the recommendation of
CASAC, the Administrator has decided to set the level
of the annual standard at the lower bound of the original

pe 36a

range, 50 »g/m*, expected annual arithmetic mean. This
standard provides a reasonable margin of safety against
the serious effect of long-term degradation in lung func-
tion, which has been judged likely at estimated PM,,
levels above 80-90 »g/m° and for which there is some
evidence at PM,, levels above §0 to 65 »g/m*. Such a
standard also provides reasonabie pretection against the
less serious symptomatic effects for which some studies
provide evidence at PM,, levels down to 50 xg/m*. Al-
though some small risk of increased respiratory symptoms
may exist at this concentration, the available data are
currently inconclusive on this point. Moreover, the staff
and CASAC have recommended that the combined pro-
tection afforded by both 24-hour and annual standards
be considered in selecting the final standard level. In this
regard, analyses of air quality data show that imple-
mentation of the 24-hour standard will substantially re-
duce annual levels in a number of areas to below 50
ug/m*, adding to the protection afforded by the annual
standard in areas with higher 24-hour peak to mean
ratios (SPA, p. 61; Freas, 1986). Based on the present
evidence with respect te risks associated with annual ex-
posures, the Administrator finds that the annual and 24-
hour standards announced today provide an adequate
margin of safety.

= * * *

VI. Summary of Salient Public Comments and
Agency Responses

An overview of public comments on the major aspects
of the March 20, 1984 proposal are presented in Section
II. The most important comments on specific issues are
categorized and summarized below together with Agency
responses. A more comprehensive compilation of com-
ments and Agency responses is contained in a separate
Response to Comments Document that has been placed in
the Docket (No. A-82-37).

“4. Raedins

37a

A. Health Effects Criteria and Selection of the Primary
Standards

1. Indicator for the Primary Standards

Comments: PM, rather than PM,, should be used as
the indicator for the primary standards because PM,
more accurately reflects particle deposition in the thoracic
regions, provides an ample margin of safety in protecting
health, and puts less emphasis on coarse particles that are
relatively inert than does PM...

Agency Response: EPA considered the major analysis
(Swift and Proctor, 1982) and preliminary arguments
(AMC, 1982) in support of a PM, indicator in develop-
ing the 1984 proposal. Although EPA deferred judgment
pending additional analysis and review, the decision to
propose PM,, and not PM, was based, in part, on reserva-
tions concerning the PM, indicator. The likelihood that
the available data from mouthpiece studies overstated
thoracic deposition during “natural” breathing was rec-
ognized in a qualitative sense by CASAC icf. July 1981
transcript, p. 581; Docket No. A-82-37) and presented as
one reason for recommending PM,, rather than PM,, or
TSP as an indicator. The 1982 staff paper re-
flected this argument in recommending 10 »m rather
than 15um as the cutpoint for the indicator (SP, pp.
76-77). The criteria document addendum points out that
assumptions used in the quantitative analyses used to
support PM, (Swift and Proctor, 1982) appear to under-
estimate thoracic particle deposition; this underestima-
tion would reduce any margin of safety associated with
an indicator derived from these data. Extension of the
Swift and Proctor analysis itself suggests that apprexi-
mately 10 to 20% of 10 »m partcles could penetrate to
the thoracic region, rather than the 0% penetration im-
plied by some commenters who argued for a “D,” at 10
um.

The Swift and Proctor analysis as well as several more
recent analyses and experimental studies of particle depo-

38a

sition are reviewed in the criteria document and staff
paper addendum. The more recent assessments tend to
support the original proposal of PM,,. The criteria docu-
ment addendum compares the work of Miller et al.
(1986), using the more recent deposition data, with the
Swift and Proctor analysis and confirms that the latter
understates deposition of particles larger than 6 um in
individuals who habitually breathe through the mouth.

The more recent data also show some fraction of par-
ticles of 10 »m and larger can penetrate as far as the
alveolar region (CDA, Figure 2-1). The risk associated
with deposition of insoluble coarse particles in this region
is of particular concern because of slow clearance time
(CPA, p. 2-6). Although removal in the tracheobronchial
region is more rapid, deposition of coarse particles in the
tracheobronchial region may be associated with broncho-
constriction and alteration of clearance mechanisms (SP,
Table 5-2). The 1982 staff paper took these factors into
account in the original recommendation for a 10 »m in-
dicator that included all of the fine and a portion of the
coarse fraction.

After considering these updated assessments, the EPA
staff reaffirmed its original recommendation of PM,, as
an indicator for the standards (SP, p. 32). In reviews of
the March 20, 1984 proposal and of the criteria document
and staff paper addenda, the CASAC also reaffirmed its
recommendation for PM,, as an indicator (Lippman 1986
a,c). The majority of public comments on this issue also
favored PM...

In summary, EPA finds that the presently available
record clearly favors the PM,, indicator over the alterna-
tive PM, indicator.

Comments: Some commenters suggested that while
PM,, represents an improvement over TSP, the fine frac-
tion (<2.5 um) is of relatively greater concern to health
than the coarse fraction (2.5 to 10 um). Such comment-

a Oe A Gre te PA

39a

ers suggest that a PM.., standard is needed—in addition
to or, in some comments, instead of a PM,, standard.

Agency response: The possibility of a fine particle in-
dicator for the primary standard was examined in the
staff paper (pp. 68-70). This suggestion is based in part
on the recognition that ambient particle mass and volume
are distributed such that a rough division “minimum”
at about 1 to 3 »m separates the “fine” (smaller) and
“coarse” fractions. Each fraction has somewhat distinct
chemical and physical properties and sources. The staff,
however, noted a number of difficulties in using fine par-
ticles (less than a nominal 2.5 um) alone instead of PM,,
as the indicator for the primary standards. These in-
clude:

(1) Substantial overlap can occur between the two
modes and in some cases the division minimum can dis-
appear. Moreover, despite the differing origins and
chemistries of the modes, each is chemically heteroge-
neous. The respiratory tract, in effect, alters the ambient
distribution, with a mixture of fine and coarse modes
being deposited in both the tracheobronchial and alveolar
regions. Indeed, the 2.5 um “cut” is within the size range
of maximum efficiency for alveolar deposition (2 to 4
um). The mixing of these size fractions in the respira-
tory tract and the heterogeneity within each fraction
therefore blurs the distinction between the fractions in
terms of health effects.

(2) Coarse dusts have been associated with responses
such as bronchoconstri¢tion, altered clearance and alveo-
lar tissue damage (SP, Table 5-2). Given current infor-
mation, it would be premature to ascribe all of the effects
in the British, U.S., and other epidemiological studies to
the fine fraction, or to any single chemical entity within
that fraction.

EPA believes that a separate fine particle standard in
addition to the PM,, standard is not warranted for the
following reasons:

40a

(1) Fine mass typically comprises on the order of 40
to 70% of PM,,. Therefore, the PM,, standards provide
substantial limits on fine mass, and

(2) The limited epidemiological data presently avail-
able must provide the principal basis for any particulate
matter standard. Because these data do not separate the
effects of fine and coarse fractions, it is most reasonable
to use these data to support a single set of standards.

(3) To the extent that emerging information suggests
additional protection may be necessary, it may be more
appropriate to consider the addition of chemical-specific
(e.g., acid aerosols) standards rather than a fine particle
standard in future primary standard revisions.

2. Interpretation of Community Epidemiological
Studies

Comments: A number of commenters took issue with
EPA’s interpretation of the various analyses of London
mortality data. These commenters suggest that (a) the
London data can be used to show only an association of
excess mortality with high concentrations of pollution dur-
ing unique episodes in which BS and SO, levels exceeded
500 to 1000 »g/m*, (b) a number of the analyses suffer
from methodological flaws precluding valid conclusions,
(c) the conclusion that effects may be possible at low
pollution levels (e.g., <250 ug/m*) or that there is a
continuum of association with no identifiable threshold is
not supportable, (d) the results of Mazumdar et al.
(1982) and Ostro (1984) are more consistent with the
hypothesis that particulate matter is acting as a surro-
gate for some other causal agent rather than as a causal
agent itself, and (e) it is biologically implausible that
mortality could be affected by particulate matter at levels
below those shown by Lawther et al. (1970) to produce
morbid effects in sensitive populations.

Agency Response: EPA’s assessment of the various
London mortality analysis is discussed at length in the

eee hee

Nee De eee ee ee ee

OLR OMA Blt Laon?

4la

criteria document, the staff paper, and the addenda to
these documents. The 1982 criteria document found that
in the context of historical London exposures, these data
indicate clear increases in daily mortality occurred with
BS and SO, concentrations in excess of 1000 »g/m* with
some indications of likely increases in daily mortality at
levels of both pollutants in the range of 500 »g/m* or
more (CD, Table 14-7). These original conclusions on
likely effects levels, based largely on the Martin and Brad-
ley (1960) and Ware et al. (1981) analyses, appear rea-
sonably consistent with the original assessment of these
data by the original British investigators and the 1969
criteria document. From the re-examination of these data
by Ware et al. (1981) and the analysis of subsequent
London winters by Mazumdar et al. (1981), the criteria
document also concluded small increases in daily mortality
might occur at leveis below 500 »g/m*. The more recent
analyses of these data by Mazumdar et al. (1982), Ostro
(1984), and Shumway et al. (1983) all serve to rein-
force the possibility that effects were associated with par-
ticulate matter at concentrations below 500 p»g/m*. A
number of commenters, however, including some of the
original British investigators (Holland et al., 1985), ob-
ject to this latter suggestion.

EPA has carefully examined these studies and the var-
ious criticisms of them submitted as comments on the
proposal. In order to respond fully to these criticisms,
EPA conducted more sophisticated reanalyses of the
original London data to further determine the degree of
reliance that can be placed on the published results
(Schwartz and Marcus, 1986, CDA, Appendix A). Each
of these studies does suffer from limitations and uncer-
tainties delineated in EPA’s updated asesssment (SPA
pp. 17-23; 34-44); these limitations preclude definitive
conclusions with respect to causality as well as identifica-
tion of clear “no observed effects’ levels. Nevertheless,
EPA maintains its original interpretation, supported by
its external science advisors, that these data at least sug-

P

424

gest the possibility of effects of particulate matter at BS
levels as low as 150 »g/m* and possibly even lower. None
of the difficulties in statistical methodology or alternative
mechanisms cited by commenters provide an adequate ex-
planation for the consistent finding of association be-
tween particulate pollution and mortality at levels be-
low 500 »g/m* (as BS). The association was found for
the majority of 14 winters (analyzed individually) span-
ning a period when pollution in London and indoor heat-
ing practices showed marked changes, and including win-
ters in which BS levels did not exceed 250 pg/m*. The
relative consistency of the results from year-to-year de-
spite these changes suggests that the observed effect is
not explained by indoor air pollution or by long-term
demographic shifts in the population. The findings were
consistent among different investigators, and persisted
after taking SO., temperature, and other weather vari-
ables into account, and after correcting for autocorrela-
tion structure.

The principal arguments for the suggestion by some
(including Mazumdar et al., 1982) that smoke may be
acting as a surrogate for some more toxic pollutant or
related non-pollution variable are: (1) The coefficients
in the regression equations appear to increase with de-
creasing pollution across the 14 winters, (2) surrogate
behavior is commonly observed in statistical analyses,
(3) the work of Lawther suggests a threshold for mor-
bidity at around 250 »g/m* as BS; hence mortality would
not be expected at lower levels. While the possibility of
surrogate behavior remains, the above arguments do not
demonstrate that smoke acts as a surrogate for non-
pollution variables. The trend toward higher coefficients
with lower pollution is not clearly consistent in the
Mazumdar and Ostro regressions. The existence of
higher coefficients in later years, however, prompted these
authors to suggest some plausible alternative to non-
pollution surrogates, including: (a) The possibility that
the composition of pollution changed with time, with an

ee a ae C
Cle

43a

increase in more toxic components, and (b) because the
gravimetric mass of particles in the range under 10 »m
may not have declined as much as did the black carbon
content detected in the smoke measurement (Lodge, 1986),
coefficients related only to smoke might be expected to in-
crease. An additional possibility suggested by Schwartz
and Marcus is that the effect of higher pollution epi-
sodes in earlier winters was blunted by public awareness
(and hence reduced exposure) or by a tendency for the
most susceptible individuals to succumb on an early day
of a multi-day pollution episode.

The use of the Lawther morbidity data as a threshold
for mortality is questionable. The London mortality data
involve an unequivocal endpoint in a relatively large pop-
ulation (several hundred per day) over a 14 year period.
As pointed out by Roth et al. (1986), although the bron-
chitic population studied was clearly susceptible, the ef-
fects indicator used by Lawther was a relatively insen-
sitive one. Moreover, the threshold was determined not
by rigorous analysis, but by visual examination of strip
chart data. Although the principal author strongly ob-
jects (Lawther, 1982), the criteria document points out
that the data do not clearly indicate an effects threshold
at 250 »g/m*. Furthermore, the simple correlation re-
sults provided by Lawther et al. (1970) suggest the pos-
sibility that a more sophisticated analysis jointly incor-
porating pollution and weather factors might have found
increased morbidity occurring at lower levels. The recent
findings of small changes in pulmonary function at lower
particulate matter levels in the U.S. and the Netherlands
(See Table 1) support the notion that 250 »g/m®* (in this
case as PM,,) is not a reliable effects threshold.

Comments: The derivation of the proposed range of
levels for the annual primary standard is without scien-
tific basis. In particular, limitations in the two major
series of studies used preclude finding effects of particu-
late matter at the lower TSP levels shown. In addition,

*

44a

the conversion of the results of these studies to PM,,
uses an inappropriately low PM,,/T

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/brief%3Amicro_IA40385020_2920%3A1. Public record. Not legal advice.