1
November
30,
1995
EPA­
SAB­
CASAC­
LTR­
96­
002
Honorable
Carol
M.
Browner
Administrator
U.
S.
Environmental
Protection
Agency
401
M
Street,
S.
W.
Washington,
DC
20460
RE:
CASAC
Closure
on
the
Primary
Standard
Portion
of
the
Staff
Paper
for
Ozone
Dear
Ms.
Browner:

A
Panel
of
the
Clean
Air
Scientific
Advisory
Committee
(
CASAC)
of
EPA's
Science
Advisory
Board
(
SAB)
met
on
March
22,
1995,
to
review
a
draft
of
the
primary
standard
part
of
the
document
entitled
Review
of
National
Ambient
Air
Quality
Standards
for
Ozone
Assessment
of
Scientific
and
Technical
Information
OAQPS
Staff
Paper.
At
that
time,
a
draft
of
the
secondary
standard
portion
of
the
document
was
not
completed.
At
the
March
meeting,
the
Panel
made
extensive
recommendations
for
strengthening
the
document.
In
August
1995,
a
revised
Staff
Paper,
which
included
a
first
draft
of
the
secondary
standard
portion
was
sent
to
CASAC
panel
members
for
review.
On
September
19
and
20,
1995,
the
Panel
met
to
compete
this
review.
The
Panel
members'
comments
reflect
their
satisfaction
with
the
improvements
made
in
the
scientific
quality
and
completeness
of
the
primary
standard
portion
of
the
Staff
Paper.
The
changes
made
in
that
portion
of
the
document
are
consistent
with
CASAC's
recommendations.
However,
the
Panel
Members
provided
additional
comments
to
your
staff
at
the
meeting
and
subsequently
in
writing.
Although
the
Panel
would
like
to
have
these
comments
considered
for
incorporation
in
the
Staff
Paper,
the
Panel
did
not
feel
that
it
was
necessary
to
review
another
revised
version
and
came
to
closure
on
the
primary
standard
portion.
It
was
the
consensus
of
the
Panel
that
although
our
understanding
of
the
health
effects
of
ozone
is
far
from
complete,
the
document
provides
an
adequate
scientific
basis
for
making
regulatory
decisions
concerning
a
primary
ozone
standard.

The
Panel
could
not
come
to
closure,
however,
on
the
secondary
standard
2
portion
of
the
Staff
Paper
which
was
a
first
draft.
To
facilitate
further
development
of
this
part
of
the
Staff
Paper,
the
Panel
members
have
provided
detailed
comments
to
your
staff.
The
Panel
felt
that
the
suggested
revisions
were
extensive
enough
to
warrant
a
review
of
the
next
draft.

I
would
like
to
summarize
for
you
the
Panel's
recommendations
concerning
the
primary
standard.
It
was
the
consensus
of
the
Panel
that
EPA's
selection
of
ozone
as
the
surrogate
for
controlling
photochemical
oxidants
is
correct.
It
was
also
the
consensus
of
the
Panel
that
an
8­
hour
standard
was
more
appropriate
for
a
human
health­
based
standard
than
a
1­
hour
standard.
The
Panel
was
in
unanimous
agreement
that
the
present
1­
hour
standard
be
eliminated
and
replaced
with
an
8­
hour
standard.

The
Panel
felt
that
the
weight
of
the
health
effects
evidence
indicates
that
there
is
no
threshold
concentration
for
the
onset
of
biological
responses
due
to
exposure
to
ozone
above
background
concentrations.
Based
on
information
now
available,
it
appears
that
ozone
may
elicit
a
continuum
of
biological
responses
down
to
background
concentrations.
This
means
that
the
paradigm
of
selecting
a
standard
at
the
lowestobservable
effects­
level
and
then
providing
an
"
adequate
margin
of
safety"
is
no
longer
possible.
It
further
means
that
EPA's
risk
assessments
must
play
a
central
role
in
identifying
an
appropriate
level.

To
conduct
the
risk
assessments,
the
Agency
had
to
identify
the
population
at
risk
and
the
physiological
responses
of
concern,
develop
a
model
to
estimate
the
exposure
of
this
population
to
ozone,
and
develop
a
model
to
estimate
the
probability
of
an
adverse
physiological
response
to
the
exposure.
The
Panel
agrees
with
EPA
that
the
selection
of
"
outdoor
children"
and
"
outdoor
workers,"
particularly
those
with
preexisting
respiratory
disease
are
the
appropriate
populations
with
the
highest
risks.
After
considerable
debate,
it
was
the
consensus
of
the
Panel
that
the
Agency's
criteria
for
the
determination
of
an
adverse
physiological
response
was
reasonable.
Nevertheless,
there
was
considerable
concern
that
the
criteria
for
grading
physiological
and
clinical
responses
to
ozone
was
confusing
if
not
misleading.
The
Panel
concurs,
with
the
Agency
that
the
models
selected
to
estimate
exposure
and
risk
are
appropriate
models.
However,
because
of
the
myriad
of
assumptions
that
are
made
to
estimate
population
exposure
and
risk,
large
uncertainties
exist
in
these
estimates.

The
results
of
two
of
the
risk
analyses
are
presented
in
Tables
VI­
1
and
VI­
2
in
the
Staff
Paper
and
are
reproduced
in
the
attached
tables.
The
ranges
of
the
risk
estimates
across
nine
cities
for
outdoor
children
are
presented
in
Table
VI­
1.
Because
of
the
large
number
of
stochastic
variables
used
in
the
exposure
models,
the
exposure
3
estimates
vary
from
run
to
run.
However,
the
ranges
are
not
reflective
of
all
of
the
uncertainties
associated
with
the
numerous
assumptions
that
were
made
to
develop
the
estimates.

The
single
estimates
presented
in
Table
VI­
2
do
not
reflect
any
of
the
uncertainties
associated
with
these
estimates.
(
Table
VI­
2
contains
only
the
estimated
hospital
admissions
due
to
asthma
which
account
for
over
85%
of
the
estimated
total
hospital
admissions
due
to
ozone
exposure).
These
uncertainties
need
to
be
explicitly
articulated
in
order
to
put
the
estimates
in
proper
perspective.
Nevertheless,
based
on
the
results
presented
in
these
and
other
similar
tables
presented
in
the
Staff
Paper,
the
Panel
concluded
that
there
is
no
"
bright
line"
which
distinguishes
any
of
the
proposed
standards
(
either
the
level
or
the
number
of
allowable
exceedences)
as
being
significantly
more
protective
of
public
health.
For
example,
the
differences
in
the
percent
of
outdoor
children
(
Table
VI­
1)
responding
between
the
present
standard
and
the
most
stringent
proposal
(
8H1EX
at
0.07
ppm)
are
small
and
their
ranges
overlap
for
all
health
endpoints.
In
Table
VI­
2,
the
estimates
in
row
1,
which
appeared
in
the
draft
Staff
Paper,
suggest
considerable
differences
between
the
several
options.
However,
when
ozone­
aggravated
asthma
admissions
are
compared
to
total
asthma
admissions
(
rows
5
and
6),
the
differences
between
the
various
options
are
small.
Consequently,
the
selection
of
a
specific
level
and
number
of
allowable
exceedences
is
a
policy
judgment.
Although
it
was
the
consensus
of
the
Panel
that
the
ranges
of
concentrations
and
allowable
exceedences
proposed
by
the
Agency
were
appropriate,
a
number
of
Panel
members
expressed
"
personal"
preferences
for
the
level
and
number
of
allowable
exceedences.
Of
the
ten
panel
members
who
expressed
their
opinions,
all
ten
favored
multiple
allowable
exceedences,
three
favored
a
level
of
0.08
ppm,
one
favored
the
mid
to
upper
range
(
0.08
­
0.09
ppm),
three
favored
the
upper
range
(
0.09
ppm),
one
favored
a
0.009
­
0.10
ppm
range
with
health
advisories
issued
when
the
8­
hour
ozone
concentration
was
forecasted
to
exceed
0.007
ppm,
and
two
just
endorsed
the
range
presented
by
the
Agency
as
appropriate
and
stated
that
the
selection
should
be
a
policy
decision.
The
members
who
favored
the
lower
numbers
expressed
concern
over
the
evidence
for
chronic
deep
lung
inflammation
from
the
controlled
human
and
animal
exposure
studies
and
the
observations
of
pain
on
deep
inspiration
in
some
subjects.

Because
there
is
no
apparent
threshold
for
responses
and
no
"
bright
line"
in
the
risk
assessment,
a
number
of
panel
members
recommended
that
an
expanded
air
pollution
warning
system
be
initiated
so
that
sensitive
individuals
can
take
appropriate
"
exposure
avoidance"
behavior.
Since
many
areas
of
the
country
already
have
an
infrastructure
in
place
to
designate
"
ozone
action
days"
when
voluntary
emission
4
reduction
measures
are
put
in
place,
this
idea
may
be
fairly
easy
to
implement.

It
was
also
the
consensus
of
the
Panel
that
the
form
of
the
8­
hr
standard
be
more
robust
than
the
present
1­
hour
standard.
The
present
standard
is
based
on
an
extreme
value
statistic
which
is
significantly
dependent
on
stochastic
processes
such
as
extreme
meteorological
conditions.
The
result
is
that
areas
which
are
near
attainment
will
randomly
flip
in
and
out
of
compliance.
A
more
robust,
concentrationbased
form
will
minimize
the
"
flip­
flops,"
and
provide
some
insulation
from
the
impacts
of
extreme
meteorological
events.
The
Panel
also
endorses
the
staff
recommendation
for
creating
a
"
too
close
to
call"
category.

Since
the
last
ozone
NAAQS
review,
the
scientific
community
has
made
great
strides
in
their
understanding
of
the
health
effects
of
ozone
exposure
because
of
ongoing
research
programs.
Panel
members
were
very
impressed
with
how
much
more
we
understand
now
as
compared
to
the
prior
round.
Nevertheless,
there
are
still
many
gaps
in
our
knowledge
and
large
uncertainties
in
many
of
the
assessments.
For
example,
there
is
little
information
available
on
the
frequency
of
human
activity
patterns
involving
outdoor
physical
exercise.
Little
is
also
known
about
the
possible
chronic
health
impacts
of
ozone
exposure
over
a
period
of
many
years.
In
addition,
there
is
no
clear
understanding
of
the
significance
of
the
inflammatory
response
inferred
from
the
broncholavage
data.
Panel
members
stated,
however,
that
the
scientific
community
is
now
in
a
position
to
frame
the
questions
that
need
to
be
better
resolved
so
the
uncertainties
can
be
reduced
before
the
next
ozone
review
in
5
years.
For
this
reason,
it
is
important
that
research
efforts
on
the
health
and
ecological
effects
of
ozone
not
be
reduced
because
we
have
come
to
closure
on
this
review.

CASAC
would
appreciate
being
kept
informed
of
progress
on
establishing
a
revised
or
new
ozone
standard,
and
plans
for
research
on
ozone
effects.
Please
do
not
hesitate
to
contact
me
if
CASAC
can
be
of
further
assistance
in
this
matter.
We
look
forward
to
receiving
the
revisions
of
the
secondary
standard
portion
of
the
Staff
Paper.

Sincerely,

Dr.
George
T.
Wolff,
Chair
Clean
Air
Scientific
Advisory
Committee
5
Page
left
blank
to
accomodate
insert
table
­
see
meeting
file
or
report
file
for
a
copy
of
this
page.
6
Table
VI­
2
(
revised)

ESTIMATED
HOSPITAL
ADMISSIONS
FOR
ASTHMATICS
IN
THE
NEW
YORK
CITY
AREA
1H1EX
0.12
1H1EX
0.10
8H1EX
0.10
8H1EX
0.09
8H1EX
0.08
8H1EX
0.07
8H5EX
0.09
8H5EX
0.08
AS
IS
Excess
Admissionsa
210
130
240
180
110
60
180
120
=
385d
%
^
from
present
std
0%
­
38%
+
14%
­
14%
­
48%
­
71%
­
14%
­
42%
+
83%

Excess
+
backgroundb
890
810
920
860
790
740
860
800
1065e
%
^
from
present
std
0%
­
9%
+
3%
­
3%
­
11%
­
17%
­
3%
­
10%
+
20%

All
asthma
admissionsc
28,295
28,215
28,325
28,265
28,195
28,145
28,265
28,205
28,470f
%
^
from
present
std
0%
­
0.3%
+
0.1%
­
0.1%
­
0.4%
­
0.5%
­
0.1%
­
0.3%
+
0.6%

a
­
excess
asthma
admissions
attributed
to
ozone
levels
exceeding
a
background
concentration
of
0.04
ppm;
from
Table
VI­
2,
page
155
in
the
August
1995
OAQPS
Draft
Staff
Paper
b
­
asthma
admissions
included
in
(
a)
plus
those
due
to
background
ozone
concentrations;
admissions
due
to
background
=
1065e
­
385d
=
680
c
­
asthma
admissions
due
to
all
causes
=
28,470f
­
385d
­
Excess
Admissions
from
row
1
d
­
estimated
from
Figure
V­
15,
page
125
in
the
August
1995
OAQPS
Draft
Staff
Paper
e
­
from
page
127,
line
13
in
the
August
1995
OAQPS
Draft
Staff
Paper
f
­
total
admissions
from
asthma
=
total
asthmatics
(
365,000
­
from
page
126,
line
24)
x
hospitalization
rate
(
78/
1000
asthmatics
­
from
page
126,

line
29)
7
i
SCIENCE
ADVISORY
BOARD
CLEAN
AIR
SCIENTIFIC
ADVISORY
COMMITTEE
OZONE
PANEL
ROSTER
Chair
Dr.
George
T.
Wolff,
General
Motors
Environmental
&
Energy
Staff,
Detroit,
MI
Members
Dr.
Stephen
M.
Ayres,
Office
of
International
Health
Programs,
Virginia
Commonwealth
University,
Medical
College
of
Virginia,
Richmond,
VA
Dr.
Jay
S.
Jacobson,
Boyce
Thompson
Institute,
Cornell
University,
Ithaca,
NY
Dr.
Joe
L.
Mauderly,
Inhalation
Toxicology
Research
Institute,
Lovelace
Biomedical
&
Environmental
Research
Institute,
Albuquerque,
NM
Dr.
Paulette
Middleton,
Science
&
Policy
Associates,
Inc.,
Boulder,
CO
(
did
not
participate)

Dr.
James
H.
Price,
Jr.,
Texas
Natural
Resource
Conservation
Commission,
Austin,
TX
Consultants
to
CASAC
Dr.
Stephen
D.
Colome,
Integrated
Environmental
Services,
University
Tower,
Irvine,
CA
Dr.
A.
Myrick
Freeman,
Department
of
Economics,
Bowdoin
College,,
Brunswick,
ME
Dr.
Allan
Legge,
Biosphere
Solutions,
Calgary,
Alberta,
CANADA
Dr.
Morton
Lippmann,
Institute
of
Environmental
Medicine,
New
York
University
Medical
Center,
Tuxedo,
NY
Dr.
William
Manning,
Department
of
Plant
Pathology,
University
of
Massachusetts,
Amherst,
MA
Dr.
Roger
O.
McClellan,
Chemical
Industry
Institute
of
Toxicology,
Research
Triangle
Park,
NC
Dr.
D.
Warner
North,
Decision
Focus,
Inc.,
Mountain
View,
CA
Dr.
Frank
E.
Speizer,
Harvard
Medical
School,
Channing
Lab,
Boston,
MA
Dr.
George
Taylor,
Biological
Services
Center,
Desert
Research
Institute,
University
of
Nevada,
Reno,
NV
Dr.
Mark
J.
Utell,
Pulmonary
Disease
Unit,
University
of
Rochester
Medical
Center,
Rochester,
NY
Science
Advisory
Board
Staff
Mr.
A.
Robert
Flaak,
Designated
Federal
Official,
U.
S.
Environmental
Protection
Agency,
Science
Advisory
Board
(
1400F),
401
M
Street,
SW,
Washington,
DC
20460
ii
Ms.
Connie
Valentine,
Staff
Secretary,
U.
S.
Environmental
Protection
Agency,
Science
Advisory
Board
(
1400F),
401
M
Street,
SW,
Washington,
DC
20460
NOTICE
This
report
has
been
written
as
part
of
the
activities
of
the
Science
Advisory
Board,
a
public
advisory
group
providing
extramural
scientific
information
and
advice
to
the
Administrator
and
other
officials
of
the
Environmental
Protection
Agency.
The
Board
is
structured
to
provide
balanced,
expert
assessment
of
scientific
matters
related
to
problems
facing
the
Agency.
This
report
has
not
been
reviewed
for
approval
by
the
Agency
and,
hence,
the
contents
of
this
report
do
not
necessarily
represent
the
views
and
policies
of
the
Environmental
Protection
Agency,
nor
of
other
agencies
in
the
Executive
Branch
of
the
Federal
government,
nor
does
mention
of
trade
names
or
commercial
products
constitute
a
recommendation
for
use.
DISTRIBUTION
LIST
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Deputy
Administrator
Assistant
Administrators
Director,
Office
of
Air
Quality
Planning
and
Standards,
OAR
Director,
Office
of
Science
Policy,
ORD
EPA
Regional
Administrators
EPA
Laboratory
Directors
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Headquarters
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Regional
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