A­
99­
02
IV­
D­
01
Responses
to
Significant
Comments
on
the
Proposed
Revision
to
the
Definition
of
Volatile
Organic
Compounds
­
Exclusion
of
t­
Butyl
Acetate
64
FR
52731,
September
30,
1999
Docket
Number
OAR­
2003­
0084
U.
S.
Environmental
Protection
Agency
October
26,
2004
2
This
document,
along
with
the
notice
of
final
rulemaking,
presents
the
response
of
the
Environmental
Protection
Agency
(
EPA)
to
significant
public
comments
received
on
the
proposed
rule
making
entitled
"
Revision
to
Definition
of
Volatile
Organic
Compounds
­
Exclusion
of
t­
Butyl
Acetate"
published
Thursday,
September
30,
1999
(
64
FR
52731).
The
responses
presented
in
this
document
are
intended
to
augment
the
responses
to
comments
that
appear
in
the
notice
of
final
rulemaking.
The
full
text
of
the
comments
referred
to
in
this
document
is
located
in
the
docket
for
this
action,
which
has
docket
number
OAR­
2003­
0084
(
legacy
docket
A­
99­
02).
This
docket
is
located
at
the
Air
and
Radiation
Docket
and
Information
Center
(
6102),
U.
S.
Environmental
Protection
Agency,
1200
Pennsylvania
Avenue,
NW,
Washington,
DC
20460.

Comments
have
been
summarized
by
the
EPA
below,
followed
by
EPA
response.
Comments
on
a
particular
subject
have
been
grouped
together.
Individual
comments
or
groups
of
similar
comments
are
numbered
consecutively
here
for
easy
referral.
Often
the
same
or
similar
comment
was
made
by
several
commenters.
The
name
of
commenters
associated
with
particular
comments
are
given
in
the
summary
of
comments
below.
The
number
beside
the
commenter's
name
is
the
document
number
placed
by
EPA
on
the
comment
letter
when
it
was
logged
into
the
docket.

The
Overall
Intent
of
the
Exemption
Policy
Comment
1.
The
primary
purpose
of
an
exemption
policy
should
be
to
encourage
replacement
of
current
emissions
with
emissions
of
compounds
with
lower
adverse
environmental
impacts
for
applications
where
elimination
of
emissions
is
not
feasible.
[
W.
P.
L.
Carter
(
II­
D­
15)].
The
EPA
should
adopt
as
a
general
policy
the
expansion
of
VOC
delisting
opportunities
for
negligibly
reactive
compounds
to
encourage
substitution
of
highly
reactive
compounds.
The
use
of
a
molar
comparison
with
ethane
would
prevent
EPA
from
exempting
more
compounds.
This
would
impede
substitution
of
less
reactive
compounds
for
more
reactive
compounds.
Restricting
the
availability
of
the
exemption
would
not
encourage
pollution
prevention.
[
The
Aluminum
Association
of
America
(
II­
D­
17)].
The
EPA
should
design
VOC
listing
criteria
to
minimize
ozone
formation
by
encouraging
use
of
compounds
that
would
displace
materials
already
in
use
that
have
higher
propensity
for
ozone
formation.
[
Penreco
and
Printing
Industries
of
America
(
IID
18)].
The
proposed
change
to
per
mole
basis
will
actually
impair
efforts
to
improve
air
quality
by
limiting
the
number
of
exempt
compounds
and
reducing
opportunities
for
product
formulators
to
use
lower
reactivity
compounds
in
place
of
highly
reactive
VOCs
[
Chemical
Manufacturers
Association
(
II­
D­
28)].
The
EPA
should
eventually
move
toward
a
solvent
substitution
policy
based
on
individual
VOC
reactivities
[
Eastman
Chemical
Company
(
II­
D­
31)].

Response:
One
of
the
most
pervasive
themes
in
the
comments
received
is
the
contention
that
EPA
should
move
to
a
solvent
substitution
program
whose
purpose
should
be
to
encourage
substitution
of
lower
reactive
compounds
for
higher
reactive
compounds.
The
intent
of
EPA's
current
VOC
exemption
policy,
however,
is
to
avoid
placing
an
undue
regulatory
burden
on
the
use
of
compounds
that
do
not
significantly
contribute
to
the
formation
of
harmful
concentrations
of
ozone.
Once
a
compound
is
exempted,
emissions
of
the
compound
may
increase
significantly
3
due
to
substitution
and
new
uses
of
the
compound.
Because
these
potential
increases
are
exempt
from
control,
it
is
important
that
the
compounds
be
negligibly
reactive
and
not
simply
marginally
less
reactive
than
compounds
that
they
may
replace.
If
by
exempting
negligibly
reactive
compounds
EPA
encourages
the
substitution
of
negligibly
reactive
compounds
for
highly
reactive
compounds,
this
is
an
added
benefit.

EPA
is
currently
evaluating
a
variety
of
scientific,
legal,
and
practical
issues
associated
with
the
design
and
implementation
of
a
policy
to
encourage
further
substitution,
such
as
the
use
of
VOC
reactivity
scales.
To
address
these
issues,
EPA
is
working
with
the
State
of
California
and
the
Reactivity
Research
Working
Group,
a
government/
industry/
academic
working
group
established
under
NARSTO
(
formerly
the
North
American
Research
Strategy
for
Tropospheric
Ozone)
to
identify
research
priorities
related
to
VOC
reactivity.
The
results
of
these
efforts
will
be
considered
by
EPA
as
part
of
a
multi­
year
review
of
our
current
VOC
policy
and
addressed
through
future
rulemakings.

Mass
v.
Molar
Basis
for
Comparison
of
VOCs
Comment
2.
The
ideal
basis
for
making
comparisons
for
VOC
exemption
decisions
would
be
atmospheric
impact
per
unit
of
use
in
production
or
economic
activity.
It
is
difficult
to
do
this
directly
since
it
would
depend
on
the
application
involved.
The
best
one
could
do
would
be
to
provide
the
best
approximation
to
the
impact
of
use.
Solvents
will
often
be
substituted
on
a
volume
basis.
The
volume
basis
would
be
better
approximated
by
mass
than
by
moles
[
W.
P.
L.
Carter
(
II­
D­
15)].

Response:
In
concept,
the
idea
of
comparing
environmental
impact
when
substituting
a
volume
of
a
lower
reactivity
compound
for
an
equal
volume
of
a
higher
reactivity
compound
on
a
per
unit
of
production
basis
is
a
good
one.
This
might
conceivably
occur
in
a
paint
or
coating
where
a
volume
of
solvent
in
a
can
of
paint
is
removed
and
replaced
by
an
equal
volume
of
another
solvent
which
has
lower
reactivity.
However,
a
VOC
exemption
policy
is
not
the
same
thing
as
a
VOC
substitution
policy.
With
an
exemption,
there
is
no
guarantee
that
exempted
compounds
will
only
be
used
to
substitute
for
equal
volumes
of
non­
exempt
compounds.
In
fact,
to
many
people,
one
of
the
attractive
features
of
an
exemption
is
that
it
will
allow
more
use
of
a
compound
in
a
coating
than
would
be
allowed
ordinarily
under
reasonably
available
control
technology
(
RACT)
rules.
Currently,
State
laws
limit
the
VOC
content
of
coatings
to
certain
limits
usually
expressed
as
total
pounds
of
VOC
per
gallon
of
coating
or
as
pounds
of
total
VOC
per
gallon
of
coatings
solids.
However,
an
exempt
compound
is
not
subject
to
these
VOC
limitations
and
larger
amounts
of
the
exempt
compound
can
be
added
to
a
coating.
Therefore,
while
a
compound
with
lower
reactivity
may
be
substituted
for
a
higher
reactivity
non­
exempt
VOC,
the
substitution
may
not
be
made
at
equal
volumes.
In
other
words,
the
manufacturer
may
use
a
far
larger
amount
of
an
exempt
compound.
Equal
substitution
per
unit
of
production
cannot
be
assumed
to
occur
when
a
compound
is
exempted,
unless
additional
regulations
were
to
be
enacted
to
limit
use
of
the
exempted
solvent.
The
EPA
is
deferring
further
consideration
of
the
mole
versus
gram
issue
until
it
can
reexamine
its
exemption
policy
as
a
whole.
4
Comment
3.
Since
emissions
are
regulated
on
a
mass
basis,
reactivity
characterization
must
be
consistent
with
the
mass
basis
to
promote
environmental
progress
[
The
Aluminum
Association
of
America
(
II­
D­
17)].
The
per
gram
comparison
basis
is
the
only
proactive
way
to
measure
both
reactivity
of
organic
compounds
and
their
emissions.
[
The
Chemical
Manufacturers
Association
(
II­
D­
28)].

Response:
There
is
no
reason
why
these
two
very
different
things
(
i.
e.,
compound
reactivity
and
volume
of
emissions)
need
to
be
considered
on
the
same
basis.
Emissions
from
products
and
industrial
processes
are
easily
measured
on
a
weight
basis,
and
it
is
appropriate
to
regulate
these
on
a
basis
of
mass
of
emissions.
Reactivity
involves
chemical
reactions
for
which
calculations
are
of
necessity
made
by
chemists
on
a
mole
basis.
In
the
chemical
industry,
theoretical
yields
from
chemical
reactions
are
routinely
calculated
using
moles,
and
the
manufactured
chemicals
are
then
sold
by
weight.
There
is
no
contradiction
in
this.
For
practical
reasons,
EPA
and
States
regulate
VOCs
on
a
weight
basis.
However,
EPA
is
working
with
the
State
of
California
and
the
RRWG
to
evaluate
other
methods
of
regulating
VOC
emissions,
such
as
through
the
use
of
VOC
reactivity
scales.
As
EPA
considers
the
future
use
of
exemptions
and
reactivity
scales,
EPA
is
deferring
further
consideration
of
the
most
appropriate
metrics
for
exemptions
until
it
can
reexamine
its
exemption
policy
as
a
whole.
For
a
further
explanation
of
the
use
of
the
mole
basis
for
reactivity
calculations
see
the
paper
"
Scientific
Basis
of
an
Improved
EPA
Policy
on
Control
of
Organic
Emissions
for
Ambient
Ozone
Reduction,"
Basil
Dimitriades,
Journal
of
the
Air
and
Waste
Management
Association,
volume
49,
page
821
­
838,
July
1999.
A
copy
of
this
article
has
been
added
to
the
docket.

Comment
4.
Ozone
formation
in
the
atmosphere
is
determined
more
by
the
overall
mass
of
organic
compounds
in
the
atmosphere
than
the
molar
reaction
rate
of
a
single
compound.
Controlling
the
mass
of
organic
carbon
compounds
would
lower
the
ozone
level
to
a
greater
extent
[
than
looking
at
molar
reactivity
of
individual
compounds.]
[
Penreco
and
Printing
Industries
of
America
(
II­
D­
18)].

Response:
Ozone
formation
is
determined
by
both
the
molar
reactivities
of
the
individual
compounds
and
their
total
mass
in
the
air.
The
EPA's
current
reactivity
policy
is
to
limit
as
much
as
is
practical
the
total
mass
of
emissions
to
the
atmosphere
of
all
volatile
organic
compounds
regardless
of
reactivity
of
individual
compounds
(
although
exempting
negligibly
reactive
compounds)
since
they
all
contribute
to
ozone
formation
to
some
degree.
In
cases
where
additional
mass­
based
control
measures
are
technologically
infeasible
but
further
control
is
needed,
EPA
is
evaluating
the
potential
for
using
reactivity
scale­
based
control
measures
or
other
measures
to
encourage
VOC
substitution
to
further
decrease
ozone
formation.

Comment
5.
If
the
EPA
does
go
to
a
per
mole
basis,
this
should
not
apply
to
compounds
(
such
as
acetone)
which
have
already
been
exempted.
[
Chemical
Manufacturers
Association
(
Including
comments
by
the
Solvents
Council
and
the
Acetone
Panel)
(
II­
D­
27)].

Response:
To
date
there
has
been
only
one
exemption,
that
of
acetone,
which
EPA
granted
5
solely
on
a
mass
comparison
basis.
The
EPA
stated
in
the
September
30,
1999
proposal
that
at
this
time
we
have
no
intention
of
revisiting
that
exemption.
However
since
EPA
is
not
changing
its
policy
regarding
gram
versus
mole
with
this
final
notice,
the
issue
is
not
presented
here.

Comment
6.
A
commenter
denies
that
per
mole
comparisons
are
the
"
proper
scientific
basis"
for
determining
VOC
reactivity
exemptions.
[
W.
P.
L.
Carter,
(
II­
D­
15)].
Other
commenters
support
the
use
of
the
"
per
gram"
basis
rather
than
the
"
per
mole
basis"
for
determining
VOC
exemptions
[
The
Aluminum
Association
(
II­
D­
17),
Penreco
and
printing
Industries
of
America,
(
II­
D­
18),
Chemical
Specialities
Manufacturers
Association
(
II­
D­
23)
Lyondell
(
II­
D­
25),
Union
Carbide
Corporation
(
II­
D­
27),
Chemical
Manufacturers
Association
(
II­
D­
28)
].
Another
commenter
says
various
scientists
suggest
both
mole
and
gram
bases
may
have
scientific
merit
(
Exxon
Chemical
Company
(
II­
D­
16)].

Response:
With
this
action,
EPA
is
not
finalizing
a
decision
that
only
molar
comparisons
are
acceptable
or
valid.
In
large
part,
EPA's
argument
for
using
a
mole
based
comparison
to
compare
the
reactivity
of
a
compound
to
that
of
ethane
for
the
purpose
of
exemption
decisions
is
based
on
smog
chamber
experiments
which
were
conducted
in
the
1970s.
These
experiments
were
done
by
comparing
ozone
produced
by
equal
molar
volumes
of
compounds
in
a
smog
chamber.
It
is
these
experiments
that
led
to
ethane
being
exempted.
More
information
about
the
original
basis
for
the
ethane
exemption
is
given
in
the
paper
"
Scientific
Basis
of
an
Improved
EPA
Policy
on
Control
of
Organic
Emissions
for
Ambient
Ozone
Reduction,"
Basil
Dimitriades,
Journal
of
the
Air
and
Waste
Management
Association,
volume
49,
page
821
­
838,
July
1999.
A
copy
of
this
article
has
been
added
to
the
docket.

Comment
7.
The
EPA's
primary
argument
for
using
mole­
based
comparisons
when
making
exemption
decisions
is
that
mole­
based
substitutions
were
used
in
the
smog
chamber
experiments
that
were
used
as
the
basis
for
EPA's
1977
policy
judgment
that
ethane
has
"
negligible"
ozone
reactivity
[
W.
P.
L.
Carter
(
II­
D­
15)].
The
chamber
studies
used
for
the
initial
ethane
exemption
do
not
provide
a
scientific
basis
to
justify
a
switch
to
a
mole
basis
[
Chemical
Manufacturers
Association
(
II­
D­
28)].
The
original
chamber
studies
which
identified
ethane
for
exemption
are
out
of
date
and
should
not
be
used
for
policy
making
now.
According
to
this
commenter,
an
EPA
scientist
has
acknowledged
this
in
a
recent
paper.
The
commenter
claims
that
there
are
a
number
of
reasons
that
the
original
studies
are
now
considered
flawed.
The
original
chamber
studies
indicate
propane,
not
ethane,
should
be
the
bench
mark
for
determining
whether
a
compound
should
be
classified
as
negligibly
reactive.
The
national
ambient
air
quality
standard
on
which
the
studies
were
based
was
considerably
more
stringent
than
the
current
ozone
standard.
[
Chemical
Manufacturers
Association
(
II­
D­
28),
comment
on
propane
also
made
by
Halogenated
Solvents
Industry
Alliance,
Inc.
(
II­
D­
26)].
Only
a
single
compound
was
used,
whereas
modern
chambers
use
multi­
components
to
evaluate
synergistic
effects.
[
W.
P.
L.
Carter
(
II­
D­
15),
Eastman
Chemical
Company
(
II­
D­
31)].
The
small
chamber
used
may
have
had
significant
wall
effects
that
could
have
led
to
high
ozone
readings.
[
Eastman
Chemical
Company
(
II­
D­
31)].

Response:
A
main
part
of
EPA's
argument
in
the
proposal
for
using
a
mole
based
comparison
to
6
compare
the
reactivity
of
a
compound
to
that
of
ethane
for
the
purpose
of
exemption
decisions
was
based
on
the
smog
chamber
experiments
which
were
conducted
in
the
1970s.
This
series
of
experiments
used
equi­
molar
amounts
of
compounds
and
determined
which
of
those
showed
ozone
concentrations
in
the
chamber
of
0.08
ppm.,
the
then
current
national
ambient
standard
for
oxidants.
Ethane,
which
resulted
in
ozone
levels
below
this
limit,
was
later
judged
to
be
negligibly
reactive
in
the
1977
policy
statement.
Propane,
which
gave
ozone
yields
right
at
0.08
ppm,
and
compounds
which
gave
higher
ozone
yields
were
not
judged
to
be
negligibly
reactive
in
the
1977
policy.

If
this
experiment
were
repeated
today,
it
might
be
done
somewhat
differently.
For
instance,
modern
chambers
use
multi­
component
mixtures
to
evaluate
synergistic
effects.
Such
multi­
pollutant
mixtures
would
likely
give
higher
ozone
yields,
so
it
is
not
obvious
what
the
results
would
be.
The
size
of
the
chamber
may
have
contributed
to
wall
effects
that
could
have
influenced
the
results.
Likewise,
the
ozone
ambient
air
quality
standard
has
been
changed
since
these
runs
were
made.
Nevertheless,
these
chamber
runs
were
conducted
according
to
acceptable
procedures
in
use
at
the
time.
The
EPA
has
no
reason
to
reject
these
experimental
results
as
an
influence
on
our
current
policy,
which
has
been
in
effect
since
1977.

Comment
8.
Several
comments
state
that
there
should
be
no
change
in
the
EPA's
exemption
policy
until
the
EPA
has
had
a
chance
to
complete
its
overall
review
of
reactivity
policy
and
determine
whether
broader
policy
changes
are
needed.
[
W.
P.
L.
Carter
(
II­
D­
15),
Exxon
Chemical
Company
(
II­
D­
16),
Chemical
Manufacturers
Association
(
II­
D­
28),
The
Aluminum
Association
of
America
(
II­
D­
17),
Penreco
and
Printing
Industries
of
America
(
II­
D­
21),
Eastman
Chemical
Company
(
II­
D­
31)].
Another
commenter
believes
further
refinement
of
the
regulatory
system
in
terms
of
reactivity
should
await
more
definitive
understanding
of
reactivity
issues.
During
the
interim,
the
mass­
based
standard
should
be
continued
[
National
Paint
and
Coatings
Association
(
II­
D­
22)].
Some
commenters
said
the
EPA
should
wait
until
the
Reactivity
Research
Working
Group
(
RRWG)
completes
its
research
program
before
making
a
policy
change
with
regard
to
VOC
exemption
decisions.
[
The
Aluminum
Association
of
America
(
II­
D­
17),
Penreco
(
II­
D­
18)].

Response:
The
EPA
has
decided
to
postpone
deciding
the
issue
of
the
gram
versus
mole
basis
for
reactivity
comparisons
with
ethane
for
VOC
exemptions
until
further
consideration
can
be
given
by
EPA
to
the
issue.
Therefore
the
exemption
of
t­
butyl
acetate
(
TBAC)
as
a
VOC
in
this
final
rule
is
based
on
policy
existing
before
the
September
30,
1999
proposal.

Comment
9.
The
molar
comparison
basis
makes
exemption
of
higher
molecular
weight
compounds
more
difficult.
[
W.
P.
L.
Carter
(
II­
D­
15)]
The
per
mole
basis
will
penalize
heavier
molecular
weight
compounds
[
The
Aluminum
Association
of
America
(
II­
D­
17),
Penreco
and
Printing
Industries
of
America
(
II­
D­
18),
Chemical
Manufacturers
Association
(
II­
D­
28)].
One
commenter
recommends
that
using
carbon
number
or
amount
(
by
weight)
of
carbon,
and
discounting
heavy
substitutes
such
as
chlorine
or
oxygen,
would
be
a
more
suitable
method
to
measure
reactivity.
[
Penreco
and
Printing
Industries
of
America
(
II­
D­
18)].
Another
comment
7
points
out
that
heavier,
higher
molecular
weight
compounds
are
less
likely
to
remain
in
the
atmosphere.
The
commenter
says
that
EPA
recognized
this
distinction
in
the
§
183(
e)
Consumer
Product
rule
[
in
40
CFR
59.209]
which
does
not
apply
to
less
volatile
products
(<
0.1
mm
Hg.,
boiling
point
>
421

F,
carbon
number
>
12.)
[
Penreco
and
Printing
Industries
of
America
(
II­
D­
18)].

Response:
Some
high
molecular
weight
compounds
have
been
found
in
the
vapor
state
in
the
atmosphere.
For
example
alkanes
with
carbon
numbers
as
high
as
C28
have
been
measured
in
the
atmosphere.
A
weight
basis
for
exemption
may
favor
such
heavy
compounds
if
the
weight
increases
more
rapidly
than
the
photochemical
reactivity
does.
One
example
of
this
is
halogenated
compounds
with
chlorine
or
bromine
atoms,
which
are
very
heavy.
A
molecule
of
such
a
compound
may
have
a
similar
photochemical
reactivity
to
an
alkane
molecule
which
has
the
same
number
of
carbon
atoms,
but
without
the
heavy
halogen
atom.
The
compounds
may
have
similar
reactivity
per
molecule
or
mole,
but
the
heavy
halogenated
compound
will
have
a
much
lower
reactivity
per
gram,
since
it
is
so
heavy.
The
idea
of
considering
reactivity
per
carbon
atom
which
one
commenter
suggests
would
reduce
the
problem
of
lowering
reactivity
per
gram
by
adding
a
heavy
atom
to
the
molecule.
Reactivity
per
carbon
atom
would
tend
to
give
more
equal
treatment
to
compounds.
This
idea
might
have
some
merit,
but
EPA
has
not
examined
all
the
implications
of
such
an
approach
and
is
not
ready
to
adopt
such
an
approach
at
this
time.
The
fact
that
EPA
Consumer
Product
rule
does
not
regulate
organic
compounds
below
0.1
mm
Hg
vapor
pressure
does
not
bear
on
the
VOC
exemption
issue.
This
vapor
pressure
exemption
is
solely
for
the
purpose
of
implementing
this
particular
rule,
and
the
rule
itself
states
unequivocally
that
this
exemption
is
not
intended
to
modify
EPA
definition
of
VOC.
Incidently,
the
Consumer
Product
rule
does
not
have
a
boiling
point
>
421

F
exemption
as
indicated
by
the
comment.

As
stated
above,
the
EPA
has
decided,
based
on
comments
received,
that
the
issue
of
gram
versus
mole
basis
is
sufficiently
complex
to
warrant
further
consideration.
The
EPA
is
making
no
policy
change
regarding
a
gram
versus
mole
basis
with
this
final
rule
for
the
TBAC
exemption.

Comment
10.
Dr.
William
Carter
refers
to
the
1977
experiments
as
being
EPA's
main
argument
for
using
a
mole­
based
approach,
since
these
experiments
were
on
an
equi­
mole
basis.
He
said
EPA
gave
no
justification
as
to
why
a
mole­
based
rather
than
a
mass­
based
substitution
was
used
in
these
experiments.
An
appropriate
way
to
deal
with
this
(
short
of
re­
doing
the
study)
is
to
make
appropriate
corrections
to
the
data
so
that
their
policy
implications
can
be
properly
interpreted.
Ethane
has
a
molecular
weight
that
is
approximately
2.3
times
lower
than
the
average
of
all
VOCs
measured
in
ambient
air.
This
means
that
had
the
substitutions
in
the
chamber
experiments
been
done
on
a
mass
basis,
the
amount
of
ethane
added
should
have
been
2.3
times
higher
that
the
amount
they
actually
used.
If
it
is
assumed
that
the
amount
of
O
3
formed
in
the
experiments
is
approximately
proportional
to
the
amount
of
VOC
added,
then
a
compound
that
is
2.3
times
less
reactive
than
ethane
should
form
about
the
same
amount
of
O
3
in
a
mass­
based
substitution
experiment
as
ethane
did
in
a
mole­
based
experiment.
In
other
words,
the
data
from
the
1977
study
could
be
used
to
support
a
mass­
based
exemption
standard
only
with
the
reactivity
8
borderline
being
reduced
by
a
factor
of
2.3.
[
W.
P.
L.
Carter
(
II­
D­
15)].

Response:
It
is
worth
considering
whether,
to
most
appropriately
use
the
reactivity
criteria
established
in
the
1977
experiments,
the
molar­
based
borderline
should
remain
as
ethane,
but
the
weight­
based
borderline
should
be
different.
As
discussed
in
response
to
Comment
7,
there
are
a
variety
of
aspects
of
the
1977
experiments
and
the
interpretation
of
their
results
that
could
be
reconsidered.
EPA
believes
that
these
issues
should
be
considered
together
as
part
of
a
broader
review
of
the
use
of
exemptions
and
reactivity
metrics.

This
issue
is
discussed
further
in
the
paper
"
Scientific
Basis
of
an
Improved
EPA
Policy
on
Control
of
Organic
Emissions
for
Ambient
Ozone
Reduction,"
Basil
Dimitriades,
Journal
of
the
Air
and
Waste
Management
Association,
volume
49,
page
821
­
838,
July
1999.
A
copy
of
this
article
has
been
added
to
the
docket.

Comment
11.
The
molar
comparison
is
the
proper
scientific
basis
and
EPA
should
not
continue
to
use
the
per
gram
comparison
basis.
[
The
Institute
of
Clean
Air
Companies
(
II­
D­
12),
Occidental
Chemical
Corporation
(
II­
D­
29),
James
C.
Berry
(
II­
D­
30),
Institute
for
Research
and
Technical
Assistance
(
II­
D­
33)].

Response:
Several
commenters
agreed
with
EPA's
position
in
the
proposal
notice
that
the
mole
comparison
is
the
most
appropriate
basis
for
comparing
reactivities
to
ethane
for
the
purpose
of
granting
exemptions.
All
the
commenters
who
opposed
the
TBAC
exemption
favor
the
per
mole
comparison
basis.
Most,
if
not
all,
of
the
commenters
who
favor
the
TBAC
exemption
think
the
per
gram
basis
should
be
used.
As
stated
above,
EPA
is
deferring
issuing
a
policy
change
on
the
gram
versus
mole
issue
at
this
time
and
is
using
the
policy
which
was
in
effect
prior
to
the
September
30,
1999
proposal.
Based
upon
the
issues
raised
by
commenters,
EPA
plans
to
reexamine
the
question
of
the
proper
basis
for
comparison
in
conjunction
with
a
larger
reappraisal
of
EPA's
exemption
policy.

Comment
12.
TBAC
reactivity
on
a
molar
basis
is
1.5
times
that
of
ethane.
The
difference
is
significant.
Why
is
this
not
given
more
emphasis?
[
James
C.
Berry
(
II­
D­
30)].

Response:
The
EPA
is
using
the
per
gram
basis
to
evaluate
the
TBAC
exemption
petition,
in
accordance
with
current
policy.
On
a
per
gram
basis,
TBAC
is
less
reactive
than
ethane.

Comment
13.
Historically,
EPA
has
evaluated
a
chemical's
reactivity
by
looking
at
the
hydroxyl
radical
reaction
rate
constant,
k
OH
.
The
k
OH
of
TBAC
and
ethane
are
4.4
x
10­
13
cm3/
molecule­
sec
and
2.7
x
10­
13
cm3/
molecule­
sec,
respectively.
By
this
standard,
TBAC
is
more
reactive
than
ethane.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
Historically,
EPA
has
evaluated
a
chemical's
reactivity
by
looking
at
the
hydroxyl
radical
reaction
rate
constant,
k
OH
.
The
first
time
that
EPA
used
the
incremental
reactivities
prepared
by
Dr.
William
P.
L.
Carter
was
when
it
exempted
cyclic,
branched
or
linear
completely
9
methylated
siloxanes
on
October
5,
1994.
Prior
to
that
time,
EPA
had
made
all
exemption
decisions
using
k
OH
values
which
expressed
the
rate
of
reaction
of
a
compound
with
the
OH
radical
and
which
were
expressed
in
units
of
cm3/
molecule­
sec.
On
the
k
OH
basis,
TBAC
would
have
a
higher
reactivity
than
ethane
and
would
not
have
been
exempted.
However,
EPA
has
used
the
incremental
reactivity
method
for
acetone
and
methyl
acetate
since
first
using
it
for
volatile
methylated
siloxanes.
The
EPA
is
using
the
incremental
reactivity
method
on
a
gram
basis
to
evaluate
this
petition,
and
on
that
basis
TBAC
is
less
reactive
than
ethane.

Comment
14.
It
is
a
basic
principle
of
chemistry
that
reactions
occur
between
compounds
on
a
molar
basis.
The
EPA
should
use
the
most
scientific
approach
for
exemption
decisions.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
Basic
chemistry
does
indicate
that
chemical
reactions
occur
on
a
molar
basis.
However,
the
contribution
of
a
VOC
to
ozone
formation
is
a
function
of
the
chain
of
chemical
reactions
in
which
the
VOC
and
its
reaction
products
participate.
The
ozone
contribution
of
this
chain
of
reactions
can
be
expressed
in
terms
of
either
moles
or
grams
of
the
VOC.
The
EPA's
current
policy
(
see
60
FR
31633)
does
allow
the
per
gram
basis.
Based
on
the
important
questions
raised
by
comments
on
the
per
gram
versus
mole
basis,
EPA
has
decided
to
defer
consideration
of
revising
policy
on
this
issue.

Comment
15.
The
Agency
appears
to
be
ignoring
the
opinions
of
its
own
experts.
Occidental
cites
statements
by
an
EPA
scientist
in
a
July
1999
Journal
of
the
Air
&
Waste
Management
Association
article
(
Scientific
Basis
of
an
Improved
EPA
Policy
on
Control
of
Organic
Emissions
for
Ambient
Ozone
Reduction)
and
statements
made
in
presentations
by
two
EPA
representatives
at
the
Photochemical
Reactivity
Workshop
held
on
May
12­
14,
1998
in
favor
of
the
mole
basis
as
opposed
to
the
gram
basis.
[
The
Institute
of
Clean
Air
Companies
(
II­
D­
12),
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
The
EPA
employees
did
make
comments
concerning
the
mole
basis
at
the
workshop
and
in
the
journal
article
cited.
Although
these
were
not
official
Agency
policy
statements,
the
EPA
has
not
ignored
these
statements.
As
the
comments
on
the
gram
versus
mole
issue
discussed
in
the
proposal
indicate,
this
is
a
complex
issue.
The
EPA
has
decided
to
defer
issuing
a
revised
policy
statement
on
this
issue
pending
further
consideration.

Comment
16.
There
is
no
meaningful
difference
between
the
reactivities
of
TBAC
and
ethane
on
a
per
mole
basis.
TBAC
has
twice
the
reactivity
of
ethane
on
a
per
mole
basis.
Both
of
these
are
on
the
low
end
of
the
reactivity
scale
in
comparison
with
most
other
organic
compounds.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
Both
ethane
and
TBAC
are
near
the
low
end
of
the
reactivity
scale,
although
TBAC
is
1.5
to
2.3
times
as
high
as
ethane
on
a
per
mole
basis.
The
EPA
considers
this
to
be
significant.
TBAC
has
lower
reactivity
than
ethane
on
a
gram
basis.
10
Comment
17.
Lyondell
states
that
Occidental
Chemical
Corporation
(
or
Occidental)
asserts
that
EPA's
1978
reactivity
policy
is
clear
that
comparisons
of
reactivity
must
be
done
on
a
molar,
not
gram
basis.
Lyondell
says
that
the
Occidental
assertion
is
untrue.
Assuming
the
1977
policy
is
meant,
since
there
is
no
1978
policy,
this
policy
statement
does
not
mention
the
mole
vs.
gram
distinction.
As
discussed
above,
until
the
proposal
to
exempt
TBAC
was
issued,
every
EPA
document
that
mentioned
this
issue
stated
that
the
EPA
would
compare
compounds
to
ethane
on
a
per
gram
basis.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
The
1977
policy
did
not
specify
a
basis,
either
per
gram
or
per
mole,
for
determining
VOC
exemptions.
However,
early
exemptions
seem
to
have
been
made
using
either
k
OH
values
expressed
on
a
per
molecule
basis
or
data
from
smog
chamber
experiments
conducted
on
a
molar
basis.
In
fact,
all
compounds
which
were
exempted
prior
to
the
acetone
exemption
in
1995
are
less
reactive
than
ethane
on
a
mole
basis.
Acetone
is
the
only
exempted
compound
which
is
not
less
reactive
than
ethane
on
a
mole
basis.
The
1977
policy
does
not
actually
say
that
ethane
is
to
be
used
as
a
benchmark
for
comparisons.
The
use
of
ethane
as
a
benchmark
came
later
as
petitioners
made
the
argument
that
the
compounds
named
in
their
petitions
were
less
reactive
than
ethane
which
was
listed
as
negligibly
reactive
in
the
1977
policy.
The
fact
that
ethane
was
listed
as
negligibly
reactive
in
large
part
based
on
experiments
which
were
conducted
by
an
equi­
molar
comparison
of
compounds
in
a
smog
chamber
is
not
spelled
out
in
the
1977
policy.
The
EPA
discussed
the
gram
vs
mole
issue
in
the
acetone
proposal
and
in
the
final
rule
which
was
issued
in
1995.
In
the
acetone
exemption
decision,
EPA
explicitly
chose
to
use
the
weight
(
gram)
basis
for
the
ethane
comparison.
The
EPA
also
mentioned
the
per
gram
basis
as
an
approach
"
presently
favored
­
but
not
officially
endorsed"
in
a
1995
report
to
Congress
on
consumer
products.
In
the
methyl
acetate
exemption
(
63
FR
17331)
in
1998,
EPA
indicated
that
it
had
considered
that
action
on
both
a
gram
and
mole
basis.

Comment
18.
Lyondell
states
that
Occidental
claims
that
EPA
made
an
"
exception"
to
its
permole
policy
when
it
exempted
acetone
and
that
the
use
of
acetone
is
soaring
as
a
result
of
this
"
mistake."
Lyondell
states
that
the
acetone
decision
was
not
an
exception.
It
was
simply
the
first
time
that
the
Agency
had
to
address
the
mole
vs.
gram
issue
explicitly.
In
that
action,
EPA
said
it
would
compare
compounds
to
ethane
on
a
gram
basis.
The
use
of
acetone
has
not
"
soared"
as
a
result
of
being
excluded
as
a
VOC.
Annual
growth
rates
of
acetone
sales
are
only
slightly
higher
than
before
the
exemption
was
granted.
In
any
event,
much
of
the
acetone
being
used
is
replacing
compounds
with
substantially
higher
photochemical
reactivity.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
The
acetone
exemption
was
the
first
time
that
EPA
specified
a
comparison
basis
(
either
per
gram
or
per
mole)
for
making
reactivity
determinations.
Prior
to
this
time,
EPA
had
made
exemption
determinations
using
k
OH
values
(
except
for
the
case
of
volatile
methyl
siloxanes
as
explained
below.).
The
k
OH
values
are
on
a
molecule
basis,
which
is
analogous
to
a
mole
basis,
but
the
basis
was
not
directly
stated
prior
to
the
acetone
action.
The
EPA
first
considered
a
new
system
of
incremental
reactivities
developed
by
Dr.
W.
P.
L.
Carter
in
1994
for
methylated
siloxanes.
These
siloxane
compounds
were
very
unusual
in
that
they
showed
negative
reactivity,
11
which
meant
that
they
did
not
produce
ozone
on
either
a
gram
or
mole
basis.
The
EPA
used
Carter's
incremental
reactivities
again
in
the
1994
acetone
proposal.
Incremental
reactivities
were
used
instead
of
k
OH
values
for
acetone
partially
because
reaction
with
the
OH
radical
is
not
the
main
pathway
by
which
acetone
breaks
down
in
the
atmosphere.
This
was
the
only
time
until
now
that
a
compound
has
been
exempted
solely
on
a
reactivity
per
gram
basis.
Other
compounds
exempted
since
then
are
low
enough
in
reactivity
to
be
below
ethane
on
either
a
per
gram
or
per
mole
basis.
In
a
sense,
acetone
was
an
exception
in
that
it
is
the
only
compound
exempted
until
now
which
is
more
reactive
than
ethane
on
a
mole
basis.
However,
no
clearly
stated
policy
requiring
a
mole
basis
had
been
announced
prior
to
that
action.

Although
published
data
on
acetone
use
since
1995
are
difficult
to
find,
EPA
has
not
seen
any
indication
that
acetone
use
has
shown
any
unusual
expansion
since
the
exemption
of
acetone
in
1995.
The
EPA
has
not
been
able
to
obtain
quantitative
information
which
indicated
the
extent,
if
any,
to
which
acetone
has
been
substituted
for
other
more
toxic
or
more
photochemically
reactive
chemicals.

The
General
Scientific
Basis
of
the
Exemption
Policy
Comment
19.
The
Halogenated
Solvents
Industry
Alliance
argues
that
the
basis
on
which
EPA
proposed
to
exempt
TBAC
is
"
sufficiently
vague
and
lacking
in
objective
criteria"
that
the
decision
suffers
from
the
same
lack
of
an
"
intelligible
principle"
as
found
by
the
U.
S.
Court
of
Appeals
for
the
D.
C.
Circuit
in
ruling
on
the
8­
hour
ozone
NAAQS.
The
Court
found
that
EPA
had
failed
to
articulate
an
"
intelligible
principle"
used
to
select
the
level
of
the
NAAQS
and
thereby
had
assumed
an
unconstitutional
delegation
of
authority
from
Congress
to
the
executive
branch.
[
Halogenated
Solvents
Industry
Alliance
(
II­
D­
26)].

Response:
Apparently
this
commenter
is
referring
to
EPA's
statement
in
the
proposal
saying
that
the
EPA
will
evaluate
petitions
that
were
submitted
prior
to
the
September
30,
1999
proposal
notice
based
on
the
extent
of
reliance
on
past
EPA
statements
concerning
the
acceptability
of
the
per
gram
basis
and
the
extent
to
which
the
exemption
would
further
the
purpose
of
the
Clean
Air
Act.
However,
EPA
has
decided
not
to
finalize
a
change
in
the
VOC
exemption
policy
with
respect
to
the
mass
or
molar
basis
for
comparison
and
is
proceeding
with
the
final
rule
for
TBAC
based
on
the
existing
policy.
Therefore,
the
commenter's
concerns
are
not
relevant
to
this
final
rule.
Furthermore,
the
D.
C.
Circuit's
ruling
cited
by
the
commenter
has
been
overturned
by
the
Supreme
Court.

Comment
20.
Dr.
Carter
has
published
(
via
his
website)
a
more
recent
reactivity
value
for
TBAC
than
the
values
submitted
with
the
petition
and
on
which
the
decision
to
propose
the
exemption
is
based.
The
new
number
(
0.60
relative
TBAC
to
ethane
incremental
reactivity
on
a
gram
basis)
is
higher
than
the
most
recent
TBAC
value
in
the
petition
(
0.38).
The
most
recent
published
value
by
Dr.
Carter
shows
that
TBAC
is
2.32
times
as
reactive
as
ethane
on
a
molar
basis.
Dr.
Carter
has
published
3
relative
incremental
values
for
TBAC
relative
to
ethane
between
November
1996
and
August
1998.
These
values
are
0.76,
0.38
and
0.60.
Variations
of
this
magnitude
may
be
12
acceptable
for
developing
science,
but
they
are
totally
unacceptable
as
the
basis
for
regulation.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
Dr.
Carter
has
revised
his
reactivity
scales
several
times
giving
slightly
different
values
for
some
chemicals
including
TBAC.
While
the
values
for
TBAC
have
been
revised
several
times,
all
of
the
values
cited
by
the
commenter
support
the
conclusion
that
TBAC
is
less
reactive
than
ethane
on
a
mass
basis.
Variations
in
reactivity
scales
over
time,
which
are
primarily
due
to
changes
in
the
chemical
mechanism
used
to
calculate
the
scales,
can
be
problematic
for
some
regulatory
purposes.
However,
EPA
does
not
believe
that
these
types
of
changes
will
alter
the
conclusions
in
this
case.

Comment
21.
One
commenter
states
that
EPA
should
await
the
outcome
of
a
review
of
the
current
science
on
reactivity
before
it
decides
borderline
cases
such
TBAC.
[
Halogenated
Solvents
Industry
Alliance,
Inc.
(
II­
D­
26)].
Lyondell
Chemical
Company
says
that
Occidental
Chemical
Corporation
suggests
that
the
EPA
should
not
make
a
decision
about
excluding
TBAC
until
Agency
has
completed
its
reevaluation
of
its
VOC
exemption
policy.
Lyondell
says
the
reevaluation
will
take
several
years.
According
to
Lyondell,
there
is
no
reason
to
postpone
the
benefits
of
exempting
TBAC
until
EPA
is
able
to
implement
a
new
policy.
[
Lyondell
(
II­
D­
25)].

Response:
There
is
no
set
date
for
revising
the
current
policy.
This
will
depend
on
information
which
is
now
being
collected,
and
any
decision
to
make
major
revisions
to
the
policy
could
be
several
years
away.
The
EPA
thinks
that
it
has
enough
information
about
TBAC
to
proceed
with
the
exemption
of
this
particular
compound
at
this
time.

Benefits
or
Impacts
of
a
TBAC
Exemption
Comment
22.
Eighteen
commenters
specifically
indicate
their
support
for
the
TBAC
exemption.
[
HCI
USA
Distribution
Co.,
Inc.
(
II­
D­
01),
HCI
Chemtech
Distribution
Inc.
(
II­
D­
02),
BASF
Automotive
Refinish
(
II­
D­
O3),
Chase
HumiSeal
(
II­
D­
04),
The
Valspar
Corporation
(
II­
D­
05),
Advance
Chemical
Dist.
Inc
(
II­
D­
07),
Gemini
(
II­
D­
08),
DAP
(
II­
D­
10),
Finish
Technologies,
Inc
(
II­
D­
11),
Intercostal
Paint
Co.
Inc.
(
II­
D­
13),
Ashland
Specialty
Chemical
Company
(
II­
D­
14),
Penrico
and
Printing
Industries
of
America
(
II­
D­
18),
Reichold
(
II­
D­
20),
National
Paint
and
Coatings
Association
(
II­
D­
22),
Chemical
Specialities
Manufacturers
Association
(
II­
D­
23),
Firestone
Building
Products
Company
(
II­
D­
24),
Lyondell
(
II­
D­
25),
Eastman
Chemical
Company
(
II­
D­
31)].

Response:
The
EPA
recognizes
that
there
is
considerable
industrial
support
for
excluding
this
chemical
from
VOC
control
requirements.

Comment
23.
Four
commenters
oppose
the
TBAC
exemption.
[
Institute
of
Clean
Air
Companies
(
II­
D­
12),
Occidental
Chemical
Corporation
(
II­
D­
29),
James
C.
Berry
(
II­
D­
30),
Institute
for
Research
and
Technical
Assistance
(
II­
D­
33)].
(
Note
­
The
EPA
received
additional
comment
letters
after
the
close
of
the
formal
comment
period.
One
was
from
the
California
EPA
(
III­
D­
13
02),
which
urged
the
U.
S.
EPA
to
consider
carefully
any
possible
health
risks
which
might
be
associated
with
TBAC
before
proceeding
with
the
exemption.
Another
was
a
joint
letter
from
Environmental
Health
Coalition,
Natural
Resources
Defense
Council,
Sierra
Club
of
California
and
Coalition
for
Clean
Air
(
III­
D­
05),
which
urged
EPA
to
deny
the
petition.)

Response:
Several
commenters
give
reasons
why
EPA
should
not
exempt
TBAC
from
VOC
controls.
The
EPA
has
carefully
considered
these
comments,
but
has
decided
to
grant
the
exemption
for
TBAC.
The
EPA's
responses
to
these
comments
are
discussed
in
various
places
in
this
response­
to­
comment
document
with
the
specific
comments.

Comment
24.
According
to
one
commenter,
adding
TBAC
to
the
list
of
negligibly
reactive
compounds
will
greatly
encourage
substitution
of
an
environmentally
benign
product
for
products
that
purportedly
pose
greater
environmental
risks
due
to
having
greater
reactivity
or
being
hazardous
air
pollutants
(
HAPs).
[
Firestone
Building
Products
Company
(
II­
D­
24)].
Lyondell
states
that
TBAC
can
substitute
for
higher
photochemical
reactivity
solvents
and
HAPs.
In
particular,
Lyondell
states
that
several
companies
have
evaluated
TBAC
as
a
substitute
for
toluene
and
xylene,
and
that
TBAC
will
fill
a
growing
need
for
VOC
exempt
solvent.
According
to
Lyondell,
exempting
TBAC
will
substantially
reduce
ozone
formation
since
published
reactivity
values
show
toluene
and
xylene
are
20
to
50
times
as
reactive
as
TBAC.
Lyondell
also
states
that
exempting
TBAC
will
substantially
reduce
HAP
emissions.
Lyondell
estimates
that
TBAC
will
replace
more
than
150
million
pounds
of
HAP
solvents
per
year
and
thus
reduce
HAP
emissions
by
over
75,000
tons
per
year.
[
Lyondell
Chemical
Company
(
II­
D­
25)].
Several
companies
say
that
TBAC
can
be
used
as
a
substitute
for
toluene
and
xylene
and
possibly
other
HAPs
in
some
products.
[
HCI
USA
Distribution
Co.
Inc.
(
II­
D­
01),
Valspar
Corp.
(
II­
D­
05),
Advance
Chemical
Dist.
Inc
(
II­
D­
07),
Gemini
(
II­
D­
08),
DAP
(
II­
D­
10),
Finish
Technologies,
Inc.
(
II­
D­
11),
Intercostal
Paint
Co.,
Inc.
(
II­
D­
13),
Ashland
Speciality
Chemical
Company
(
II­
D­
14),
Reichold
(
II­
D­
20),
Firestone
Building
Products
Company
(
II­
D­
24),
Lyondell
(
II­
D­
25)].
One
commenter
says
that
even
though
preliminary
tests
indicate
that
TBAC
may
not
achieve
the
same
level
of
print
quality
as
the
aromatic
hydrocarbon
solvents,
EPA's
proposal
opens
the
door
for
research
that
could
ultimately
prove
useful
in
providing
regulatory
relief
and
at
the
same
time
benefit
the
environment.
[
Gravure
Association
of
America
(
II­
D­
19)].
A
coatings
producer
says
that
TBAC
would
replace
most
of
the
parachlorobenzotrifluoride
(
PCBTF)
in
its
most
popular
coatings.
[
Chase
HumiSeal
(
II­
D­
04)]
Another
company
says
that
TBAC
will
likely
be
used
in
connection
with
Oxsol
100
(
a
brand
of
PCBTF)
because
of
the
slower
evaporation
rate
of
Oxsol
100.
[
The
Valspar
Corporation
(
II­
D­
05)].
One
commenter
suggests
that
TBAC
may
be
added
as
a
thinner
on
top
of
other
solvents
already
in
low
VOC
coatings,
because
more
solvent
makes
high
solids
paints
easier
to
spray.
[
James
C.
Berry
(
II­
D­
30)].

Response:
One
of
the
main
arguments
that
the
petitioners
present
in
favor
of
the
exemption
is
that
companies
will
substitute
TBAC
for
more
environmentally
harmful
chemicals,
resulting
in
an
overall
environmental
benefit.
It
seems
evident
that
TBAC
has
physical
properties
which
would
allow
companies
to
substitute
it
for
several
commonly
used
solvents,
including
some,
such
as
toluene
and
xylene,
which
are
classified
as
hazardous
air
pollutants.
Some
toluene
and
xylene
may
14
be
replaced
because
they
are
HAPs,
and
industries
are
lowering
the
content
of
HAPs
in
many
products
used
at
facilities
subject
to
standards
under
section
112
of
the
Clean
Air
Act..
However,
EPA
is
not
able
to
confirm
how
much
HAP
reduction
will
actually
take
place.
TBAC
currently
costs
much
more
than
xylene
or
toluene.
This
cost
differential
may
play
a
role
in
whether
widespread
substitution
will
occur,
although
TBAC
may
become
less
costly
if
it
is
manufactured
in
larger
amounts.
As
EPA
stated
in
the
proposal,
the
possibility
of
substitution
is
not
the
basis
for
EPA's
decision
to
grant
the
exemption.

Comment
25.
TBAC
may
be
a
greenhouse
gas
presenting
a
problem
of
unknown
magnitude.
In
the
atmosphere
it
will
break
down
to
CO
2
which
is
a
greenhouse
gas.
[
James
C.
Berry
(
II­
D­
30)].

Response:
It
is
unlikely
that
the
use
of
TBAC
would
contribute
in
any
significant
way
to
global
warming
and
climatic
change.
Though
TBAC
can
be
oxidized
into
carbon
dioxide
(
CO
2)
and
water
vapor,
both
greenhouse
gases,
the
amount
of
these
byproducts
are
insignificant
compared
to
the
registered
inventory
of
U.
S.
greenhouse
gas
emissions.
Water
vapor
is
the
most
abundant
greenhouse
gas,
accounting
for
two
thirds
of
the
natural
greenhouse
effect.
However,
human
activities­­­
whether
the
use
of
TBAC
or
other
processes
that
release
water
vapor­­­­
have
not
significantly
altered
natural
atmospheric
concentrations
of
water
vapor.
For
this
reason,
emissions
of
water
vapor
are
not
an
area
of
concern
in
the
policy
debate
about
climate
change.
CO
2
emissions,
on
the
other
hand,
are
the
main
focus
of
the
climate
change
debate
because
atmospheric
concentrations
of
CO
2
have
increased
by
over
30%
since
pre­
industrial
times.
The
main
sources
of
U.
S.
CO
2
emissions
include
the
burning
of
fossil
fuels
(
coal,
oil
and
gas)
to
generate
energy
for
buildings,
homes
and
transportation.
1997
U.
S.
CO
2
emissions
were
1,488
million
metric
tons
of
carbon
equivalent.
An
accounting
of
the
CO
2
resulting
from
the
use
of
TBAC
would
not
likely
change
this
number.

Comment
26.
A
commenter
says
that
the
potential
increase
in
emissions
is
unlimited
and
could
be
very
large.
[
James
C.
Berry
(
II­
D­
30)].

Response:
It
is
possible
that
the
eventual
emissions
of
TBAC
could
be
very
large
once
exempted
from
substantive
controls
as
a
VOC,
since
this
compound
is
expected
to
find
wide
use
as
an
industrial
solvent.
Lyondell
has
predicted
that
TBAC
could
replace
over
75,000
tons/
year
of
hazardous
air
pollutants,
and
it
is
possible
that
replacement
of
HAPs
will
be
only
a
part
of
TBAC
usage.
To
the
extent
that
TBAC
use
replaces
the
use
of
more
photochemically
reactive
solvents,
this
increase
in
use
will
be
associated
with
a
decrease
in
ozone
formation.
However,
even
if
a
large
increase
in
TBAC
emissions
occurs,
the
compound
might
still
account
for
only
a
few
percentage
points
of
all
organic
compounds
emitted
into
the
air.
The
EPA
is
not
exempting
TBAC
from
record
keeping,
reporting
or
inventory
requirements.
If
emissions
eventually
become
so
large
that
the
situation
seems
to
present
a
problem,
EPA
will
evaluate
what,
if
any,
action
needs
to
be
taken
at
that
time.

Comment
27.
Lyondell,
the
petitioner
for
the
exemption,
states
that
the
proposal
to
exclude
TBAC
from
the
VOC
definition
is
based
on
a
substantial
body
of
scientific
evidence.
Lyondell
lists
15
several
studies
which
are
in
the
docket
on
environmental
effects
of
TBAC,
including
biodegradation,
aerosol
formation,
global
warming,
environmental
fate,
and
toxicity
studies.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
Lyondell
has
provided
a
variety
of
studies
examining
the
potential
environmental
effects
of
TBAC,
all
of
which
conclude
that
TBAC
does
not
pose
a
significant
risk
to
the
environment
or
public
health.
The
EPA
has
examined
these
materials,
and
agrees
that
the
available
data
does
not
indicate
any
serious
health
or
environmental
problems.
However,
as
discussed
below
in
response
to
Comment
33,
EPA
believes
that
it
would
be
prudent
to
conduct
further
chronic
toxicity
testing
to
resolve
the
uncertainty
associated
with
the
limited
evidence
that
is
currently
available.
Lyondell
has
agreed
to
work
with
EPA
to
further
assess
the
potential
for
chronic
toxicity.

Comment
28.
Lyondell
claims
that
exempting
TBAC
will
substantially
reduce
ozone
formation.
Based
on
reactivity
values
published
by
Dr.
Carter,
toluene
is
approximately
twenty
times
more
reactive
than
TBAC
and
m­
xylene
is
approximately
50
times
more
reactive
on
a
weight
basis.
Lyondell
concludes
that
under
conditions
where
VOC
emissions
have
their
maximum
impact
on
ozone
formation,
a
pound
of
TBAC
emitted
into
the
air
will
cause
about
50
times
less
ozone
than
a
pound
of
xylene.
According
to
Lyondell,
the
use
of
TBAC
in
place
of
high
reactivity
solvents
will
produce
substantial
reductions
in
ozone
formation
and
could
be
an
important
tool
for
addressing
the
persistent
ozone
problems
of
many
large
urban
areas.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
To
the
extent
that
TBAC
is
used
to
substitute
for
more
reactive
compounds,
such
as
toluene
or
xylene,
for
which
it
is
a
good
technical
substitute,
TBAC
use
will
help
decrease
the
ozone
formation
of
VOC
emissions.
The
California
Air
Resources
Board
has
estimated
that
maximum
substitution
could
decrease
the
ozone
forming
potential
of
statewide
emissions
by
1.3%.
While
there
is
a
possibility
that
increases
in
TBAC
use
beyond
substitition
will
offset
the
benefits
of
substitution,
EPA
believes
that
the
TBAC
exemption
will
lead
to
a
net
environmental
improvement.
However,
the
basis
for
the
EPA's
decision
to
exempt
TBAC
is
its
relative
reactivity
on
a
gram
basis
compared
to
that
of
ethane.

Comment
29.
Lyondell
states
that
TBAC
partitions
almost
exclusively
to
air
and
does
not
bioaccumulate
in
the
environment.
Specifically,
according
to
Lyondell
little
TBAC
will
accumulate
in
soil
or
water.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
Accumulation
in
ground
water
could
be
a
serious
problem,
and
EPA
would
view
any
evidence
that
this
is
occurring
with
concern.
From
the
data
on
environmental
fate
which
Lyondell
submitted,
the
EPA
does
not
anticipate
that
this
will
be
a
problem.

Comment
30.
Occidental
argues
that
because
TBAC
is
more
expensive
than
common
solvents
(
like
toluene
and
xylene)
it
will
not
replace
these
solvents,
but
will
replace
parachlorobenzotrifluoride
or
PCBTF
(
OXSOL
®
100),
which
is
manufactured
by
Occidental
and
is
several
times
more
expensive
than
TBAC.
Lyondell
contends
that
the
large
number
of
testimonial
letters
in
the
docket
gives
evidence
that
companies
will
replace
significant
amounts
of
toluene
and
16
xylene.
Lyondell
suggests
that
if
cost
is
the
only
relevant
factor
then
Occidental
would
not
be
able
to
sell
any
OXSOL,
which
is
much
more
expensive
than
virtually
every
other
solvent
used
in
the
coatings
industry.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
There
is
a
possibility
that
TBAC
may
displace
much
OXSOL
from
the
market
due
to
the
cost
difference.
However,
one
commenter
said
that
TBAC
is
not
an
exact
replacement
for
OXSOL
and
that
some
OXSOL
may
still
be
used.
It
is
not
clear
to
EPA
how
much
TBAC
will
displace
toluene
and
xylene.
See
response
to
Comment
24,
above.

Comment
31.
Occidental
suggests
that
if
TBAC
replaces
OXSOL
air
quality
would
be
harmed
because
TBAC
has
a
higher
reactivity
than
OXSOL.
Lyondell
counters
that
OXSOL
is
not
a
very
active
solvent
for
many
coating
resins,
therefore
fewer
pounds
of
TBAC
are
needed
in
a
coating.
Therefore,
when
TBAC
replaces
OXSOL,
the
reduction
in
pounds
of
solvent
emitted
outweighs
what
Lyondell
perceives
as
the
minimal
difference
in
reactivity
between
the
two
compounds.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
The
EPA
has
not
done
an
analysis
of
the
relative
propensity
for
ozone
formation
of
these
two
compounds
considering
the
amount
used
in
similar
products
formulated
with
each.
The
basis
for
exemption
of
TBAC
from
VOC
emissions
limitations
and
VOC
content
requirements
is
its
reactivity
relative
to
ethane
on
a
per
gram
basis,
not
its
relationship
to
OXSOL.

Comments
About
the
Toxicity
of
TBAC
Comment
32.
Several
commenters
discuss
whether
or
not
EPA
should
consider
a
chemical's
toxicity
when
deciding
whether
the
chemical
should
be
exempt
from
regulations
as
a
VOC.
The
Halogenated
Solvents
Industry
Alliance,
Inc.,
states
that
consideration
of
a
chemical's
toxicity
in
connection
with
EPA's
determination
as
to
whether
it
should
be
exempt
from
regulation
as
a
VOC,
without
consideration
of
the
other
regulations
that
apply
to
the
chemical,
would
be
inappropriate
and
contrary
to
the
Clean
Air
Act.
The
commenter
explains
that
hazardous
air
pollutants
are
controlled
under
section
112
of
the
CAA,
an
entirely
separate
regulatory
structure
from
the
regulations
governing
VOC
use
[(
II­
D­
26)].
The
Institute
for
Research
and
Technical
Assistance,
on
the
other
hand,
supports
the
consideration
of
environmental
effects
other
than
reactivity
(
such
as
toxicity
and
ozone
depletion)
in
making
VOC
exemption
decisions.
This
commenter
explains
that
the
maximum
achievable
control
technology
(
MACT)
standards
for
hazardous
air
pollutants
(
HAPs),
promulgated
under
section
112,
do
not
always
provide
protection
because
toxicity
data
that
would
allow
a
chemical
to
be
classified
as
a
HAP
is
not
available
or
particular
significant
uses
of
a
HAP
(
such
as
perchloroethylene
for
brake
cleaners
)
may
not
be
covered
by
a
MACT
standard.
This
commenter
urges
EPA
to
institute
a
procedure
to
evaluate
other
health
and
environmental
problems
posed
by
the
compounds
that
are
the
subject
of
petitions
for
exemption
from
VOC
regulations
and
to
delay
granting
exemptions
for
pending
petitions
until
the
necessary
data
is
available
[(
II­
D­
33)].
Occidental
Chemical
Corporation
suggests
that
EPA
has
considered
toxicity
concerns
in
granting
VOC
exemptions
in
the
past
and
cites
perchloroethylene
as
an
example
of
a
chemical
that
was
only
delisted
as
a
VOC
when
it
was
certain
that
toxicity
concerns
17
had
been
addressed.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
The
purpose
in
controlling
VOCs
is
the
attainment
of
the
Ozone
National
Ambient
Air
Quality
Standard
(
NAAQS)
for
ozone.
The
justification
for
listing
a
compound
as
"
negligibly
reactive"
and
exempting
it
from
control
requirements
in
State
implementation
plans
for
ozone
attainment
is
that
such
a
compound
contributes
insignificantly
to
ozone
formation.
However,
if
a
compound
is
exempted
from
controls,
companies
may
find
a
large
economic
advantage
to
using
increased
amounts
of
the
compound.
The
EPA
would
want
to
be
aware
of
situations
in
which
a
VOC
exemption
will
increase
the
use
of
a
compound
that
could
pose
a
significant
public
health
risk
.
As
discussed
further
below,
EPA
has
examined
the
available
evidence
concerning
the
potential
toxicity
of
TBAC
and
does
not
believe
that
there
is
sufficient
evidence
of
a
toxic
risk
associated
with
TBAC
to
warrant
foregoing
the
potential
benefits
of
reduced
ozone
formation
and
exposure.
As
for
how
non­
ozone
impacts
will
be
dealt
with
in
future
policy
decisions,
EPA
expects
to
address
these
issues
in
its
pending
review
of
the
overall
VOC
exemption
policy.

Comment
33.
A
number
of
commenters
raise
concerns
about
the
potential
toxicity
of
TBAC.
Occidental
Chemical
Corporation
[
II­
D­
29]
suggests
that
the
petitioner
has
failed
to
provide
subchronic
or
chronic
toxicity
testing
data
or
data
from
repeated
dose
studies
for
any
exposure
route.
Occidental
suggests
that
the
petitioner
has
relied
on
data
generated
for
Tertiary
Butyl
Alcohol
(
TBA)
as
a
surrogate
for
establishing
the
chronic
toxicity
of
TBAC
on
the
basis
that
TBAC
is
metabolized
by
simple
hydrolysis
to
acetic
acid
and
TBA.
Occidental
suggests
that
the
use
of
TBA
as
a
surrogate
for
TBAC's
subchronic
and
chronic
toxicity
may
not
be
appropriate
(
e.
g.,
methyl
tertiary­
butyl
ether
(
MTBE)
also
metabolizes
to
TBA
but
MTBE's
toxic
profile
is
much
different
than
that
of
TBAC.)
In
addition,
Occidental
claims
that
EPA
has
indicated
that
there
may
be
toxicological
concerns
about
TBA
itself.
Occidental
claims
that
no
chemical
should
be
introduced
into
the
marketplace
where
chronic
exposure
is
likely
without
appropriate
toxicity
studies.
Occidental
points
out
that
the
American
Conference
of
Governmental
Industrial
Hygienists
(
ACGIH)
has
decided
not
to
establish
a
short
term
exposure
limit
for
TBAC
until
additional
toxicological
data
and
industrial
hygiene
experience
is
available,
and
that
the
ACGIH
is
concerned
that
the
threshold
limit
value
listed
for
the
isomer
s­
butyl
acetate,
a
related
compound,
is
not
the
most
appropriate
level
to
ensure
safe
use
and
handling.

Other
commenters
also
suggest
denying
the
TBAC
petition
based
on
toxicity
concerns
[
Environmental
Health
Coalition
(
signed
by
Environmental
Health
Coalition,
Natural
Resources
Defense
Council,
Sierra
Club
of
California
and
Coalition
for
Clean
Air)(
III­
D­
05)]
or
delaying
a
decision
to
exempt
TBAC
until
further
toxicity
testing
can
be
completed
[
California
Environmental
Protection
Agency
(
signed
by
Air
Resources
Board,
Office
of
Environmental
Health
Hazard
Assessment,
and
State
Water
Resources
Control
Board)(
III­
D­
02),
Institute
for
Research
and
Technical
Assistance
(
III­
E­
03)].
According
to
the
California
Environmental
Protection
Agency,
(
i)
the
health
effects
data
available
for
TBAC
are
limited;
(
ii)
a
review
of
these
data
indicates
that
TBAC
has
low
acute
inhalation,
oral,
dermal
and
ocular
toxicity;
(
iii)
no
chronic,
developmental,
or
reproductive
toxicity
data
are
available
for
TBAC;
(
iii)
and
no
genetic
toxicity
or
carcinogenicity
data
are
available
for
TBAC.
Due
to
the
lack
of
information
on
TBAC,
the
commenters
assert
that
it
is
not
possible
to
assess
the
potential
for
adverse
effects
from
prolonged
exposure.
However,
TBAC
has
been
demonstrated
to
be
substantially
metabolized
to
TBA
in
rats.
18
While
genetic
toxicity
data
for
TBA
are
mixed,
information
from
one
genotoxicity
study
suggests
that
TBA
may
cause
oxidative
deoxyribonucleic
acid
(
DNA)
damage.
TBA
has
been
shown
to
induce
renal
tumors
in
male
rats
and
thyroid
tumors
in
female
mice,
raising
a
concern
that
exposure
to
TBAC
may
result
in
a
cancer
risk
[
California
Environmental
Protection
Agency
(
signed
by
Air
Resources
Board,
Office
of
Environmental
Health
Hazard
Assessment,
and
State
Water
Resources
Control
Board)(
III­
D­
02),
Environmental
Health
Coalition
(
III­
D­
05),
Institute
for
Research
and
Technical
Assistance
(
III­
E­
03)].

The
petitioners
respond
to
some
of
these
criticisms
and
state
that
Occidental's
claims
that
there
is
a
lack
of
short­
term
toxicological
information
are
inconsistent
with
the
public
record.
The
petitioners
call
attention
to
a
full
range
of
acute
toxicity
testing
that
has
been
performed
for
TBAC
and
provided
to
EPA,
which
they
claim
shows
that
TBAC
is
not
acutely
toxic
by
oral,
dermal,
or
inhalation
routes.
The
petitioners
state
that
Occidental
suggests
that
TBAC
metabolizes
to
TBA
and
acetic
acid
in
the
body
and
may
cause
developmental
effects.
The
petitioners
claim
that
acetic
acid
rapidly
metabolizes
in
the
body
and
is
not
of
concern
except
for
cases
of
extreme
exposure.
The
petitioners
acknowledge
that
TBA
can
cause
renal
tumors
in
male
rats
but
argues
that
these
effects
are
not
seen
in
humans
and
that
TBA
causes
reproductive
and
developmental
effects
in
female
mice
only
at
large
doses
far
above
environmental
exposure.
The
petitioners
explain
that,
in
summary,
TBAC
cannot
reasonably
be
expected
to
result
in
chronic
health
effects
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Since
the
the
close
of
the
comment
period,
the
California
Air
Resources
Board,
in
conjuction
with
California's
Office
of
Environmental
Health
Hazard
Assessment,
has
completed
a
draft
health
risk
assessment
of
a
VOC
exemption
for
TBAC
in
the
state
of
California.
The
assessment
quantifies
1)
the
potential
benefits
associated
with
decreased
ozone
formation
as
a
result
of
TBAC
substituting
for
more
reactive
compounds,
and
2)
the
potential
cancer
risks
associated
with
increased
exposure
to
TBAC,
based
on
the
limited
animal
testing
data
available.
A
copy
of
this
draft
assessment
is
included
in
the
docket.
[
III­
G­
05]

As
input
into
California's
assessment,
Lyondell
submitted
to
EPA
and
California
a
variety
of
additional
information
about
chronic
toxicity.
Copies
of
this
information
[
III­
H­
03],
as
well
as
a
copy
of
Lyondell's
critiques
of
California's
assessment,
are
included
in
the
docket.
[
III­
F­
14
and
III­
H­
06]

Response:
The
EPA
has
carefully
reviewed
the
limited
data
that
is
available
on
the
chronic
toxicity
of
TBAC,
including
California's
health
risk
assessment,
and
has
reviewed
the
data
available
about
the
potential
health
benefits
due
to
reduced
ozone
exposure
from
the
use
of
TBAC
as
a
substitute
for
more
reactive
substances.
The
EPA
has
concluded
that
1)
there
is
insufficient
evidence
of
a
significant
toxic
risk
to
justify
not
granting
the
exemption
petition
and
2)
granting
the
exemption
will
provide
a
net
improvement
in
public
health
and
environmental
quality.
However,
given
the
potential
for
increased
use
of
TBAC,
EPA
believes
that
it
would
be
prudent
to
conduct
further
chronic
toxicity
testing
to
resolve
the
uncertainty
associated
with
the
limited
evidence
that
is
currently
available.

In
response
to
these
concerns,
Lyondell
has
agreed
to
work
with
EPA
to
perform
testing
to
19
develop
additional
data
on
the
chronic
toxicity
of
TBAC.
As
part
of
this
effort,
Lyondell
will
conduct
a
tiered
series
of
tests
designed
to
confirm
and
elucidate
the
mechanisms
of
potential
toxicity
observed
in
the
limited
data
available.
Lyondell
will
submit
the
testing
results
to
an
independent
scientific
peer
consultation
panel
that
will
make
recommendations
to
EPA
and
Lyondell
as
to
whether
further
testing
is
appropriate.
Based
on
the
information
currently
available
and
experience
with
similar
compounds,
EPA
believes
that
the
first
tier
of
testing
is
likely
to
be
sufficient
to
resolve
much
of
the
current
uncertainty.
Until
this
round
of
tests
is
completed
and
evaluated,
Lyondell
has
agreed
to
limit
their
annual
production
of
TBAC.
The
EPA
will
take
appropriate
regulatory
action
if
the
results
of
the
testing
program
justify
such
action.

The
EPA
believes
that
moving
forward
with
the
exemption
and
simultaneously
pursuing
additional
toxicity
testing
is
a
responsible
risk
management
approach
that
allows
society
to
benefit
from
lower
ozone
exposures
while
protecting
against
other
potential
chronic
risks.

Comment
34.
Given
the
lack
of
toxicity
data,
Occidental
claims
that
the
Agency
can
not
support
claims
that
TBAC
will
be
used
as
a
substitute
for
more
toxic
substances
such
as
toluene
or
xylene,
that
the
Agency's
record
of
decision
is
deficient,
and
its
decision
is
arbitrary.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
The
proposal
does
mention
possible
environmental
benefits
from
solvent
substitution,
which
the
petitioner
claims
will
take
place
if
TBAC
is
exempted.
Based
on
evidence
presented
by
the
petitioner,
comments
received
from
potential
users,
and
the
impact
assessment
by
CARB,
EPA
believes
that,
if
exempted,
TBAC
is
likely
to
substitute
for
other
solvents
that
are
much
more
photochemically
reactive
and
are
listed
as
hazardous
air
pollutants.
While
the
exemption
decision
is
based
on
the
reactivity
comparison
with
ethane,
EPA
believes
that
the
exemption
of
TBAC
is
likely
to
result
in
a
net
environmental
improvement.

Comment
35.
Occidental
claims
that
EPA
should
have
considered
the
fact
that
formaldehyde
and
methyl
ethyl
ketone
are
the
primary
decomposition
products
of
TBAC
in
the
atmosphere
and
the
fact
that
formaldehyde
is
reactive,
toxic,
and
a
listed
HAP
[
Occidental
Chemical
Corporation
(
IID
29)].
The
petitioner
explains
that
this
claim
is
untrue
and
is
based
on
a
predicted
"
upper
limit"
mechanism
presented
in
the
petition.
This
mechanism
was
a
purely
speculative
worse
case
exercise
to
calculate
an
"
upper
limit"
reactivity.
According
to
the
petitioner,
this
mechanism
has
been
superseded
by
later
work
that
shows
that
TBAC
oxidizes
primarily
to
acetic
anhydride,
acetone
and
organic
nitrates.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
It
appears
that
Occidental's
concerns
about
the
atmospheric
decomposition
products
of
TBAC
have
been
alleviated
by
more
recent
research.

Comment
36.
Occidental
argues
that
if
TBAC
is
exempted
from
regulation
as
a
VOC,
sales
of
TBAC
would
quickly
exceed
the
high
production
volume
(
HPV)
chemical
quantity
of
one
million
pounds
per
year.
Lyondell
has
not
performed
all
the
fifteen
tests
used
by
EPA
to
screen
HPV
chemicals.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].
The
petitioner
has
stated
that
it
has
initiated
a
testing
program
designed
to
meet
the
criteria
established
under
EPA's
"
high
production
volume"
chemical
testing
program
and
that
this
testing
should
be
completed
before
the
high
20
volume
production
threshold
level
of
sales
has
occurred.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
The
completion
of
testing
under
the
HPV
Challenge
Program
is
voluntary
and
not
a
prerequisite
for
excluding
TBAc
from
the
definition
of
VOC.

Comment
37.
Both
the
South
Coast
Air
Quality
Management
District
(
SCAQMD)
and
the
California
Air
Resources
Board
(
CARB)
have
submitted
letters
to
EPA
urging
that
the
Agency
proceed
with
the
decision
to
exclude
TBAC
from
the
VOC
definition.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
The
August
20,
1997
SCAQMD
letter
(
I­
C­
04)
does
say
that
the
SCAQMD
believes
that
TBAC
should
be
exempted
and
urges
the
U.
S.
EPA
to
proceed
with
the
regulatory
actions
necessary
to
exempt
TBAC.
The
October
3,
1997
CARB
letter
(
I­
C­
09)
urges
the
EPA
to
proceed
with
its
evaluation,
but
does
not
make
a
recommendation
on
whether
or
not
TBAC
should
be
exempted.
Subsequently,
on
August
28,
2000,
the
California
Environmental
Protection
Agency
wrote
another
letter
to
the
U.
S.
EPA
(
signed
by
the
CARB,
the
Office
of
Environmental
Health
Hazard
Assessment,
and
the
State
Water
Resources
Control
Board)
[
III­
D­
02]
which
says
that
the
CARB
has
initiated
its
own
review
of
TBAC.
The
August
28
letter
expresses
concern
that
several
agencies
of
the
California
Environmental
Protection
Agency
now
have
regarding
the
U.
S.
EPA's
proposed
revision
of
the
definition
of
VOC
to
exclude
TBAC,
because
of
possible
toxic
health
effects.
All
of
these
letters
are
in
the
docket
for
this
action.

Comment
38.
Occidental
asserts
that
since
1989,
the
Agency's
policy
has
been
to
consider
the
environmental
benefits
of
a
substance
when
deciding
whether
it
should
be
exempt
from
the
definition
of
VOC
[
Occidental
Chemical
Corporation
(
II­
D­
29)].
Another
commenter
points
out
that
in
granting
VOC
exempt
status
to
certain
HCFC's,
EPA
took
into
account
the
benefits
of
the
chemicals
in
terms
of
their
potential
to
replace
ozone­
depleting
compounds
noting
that
"
there
is
a
strong
need
to
facilitate
the
use
of
environmentally
acceptable
substitutes
that
have
little
or
no
impact
on
stratospheric
ozone."
[
Chemical
Manufacturers
Association
(
II­
D­
28)].

Response:
On
January
18,
1989,
the
EPA
issued
a
rule
exempting
four
halocarbon
compounds
(
HCFC­
123,
HFC­
134a,
HCFC­
1141b,
and
HCFC­
142b)
as
VOCs
in
response
to
an
industry
petition.
The
industry
petition
cited
two
primary
reasons
for
the
request:
1)
the
low
photochemical
reactivity
of
the
compounds
(
much
lower
than
ethane)
and
2)
the
assertion
that
if
the
U.
S.
is
to
meet
its
commitments
embodied
in
the
Montreal
Protocol
on
Substances
that
Deplete
the
Ozone
Layer,
substitutes
for
the
regulated
CFCs
must
be
developed
and
unnecessary
barriers
to
their
commercialization
and
use
should
be
removed.
The
EPA
agreed
with
the
industry
contention
that
there
is
a
strong
need
to
facilitate
the
use
of
environmentally
acceptable
substitutes
that
have
little
of
no
impact
on
the
stratospheric
environment.
The
EPA
granted
the
exemptions
due
to
the
low
photochemical
reactivity
of
the
compounds
and
also
noted
that
the
effect
of
this
action
will
be
to
facilitate
the
transition
away
from
stratospheric
ozone­
depleting
chemicals
without
adversely
affecting
efforts
to
control
ground
level
ozone
concentrations.
So,
while
the
desirable
benefits
of
promoting
environmentally
acceptable
substitutes
were
considered
in
this
action,
the
exemption
was
granted
because
of
the
low
photochemical
reactivity
of
the
compounds
relative
to
ethane.
The
purpose
in
controlling
VOCs
is
the
attainment
of
the
NAAQS
for
ozone.
The
justification
for
21
listing
a
compound
as
"
negligibly
reactive"
and
exempting
it
from
control
requirements
in
State
implementation
plans
for
ozone
attainment
is
that
such
a
compound
contributes
insignificantly
to
ozone
formation.
However,
if
a
compound
is
exempted
from
controls,
companies
may
find
a
large
economic
advantage
to
using
increased
amounts
of
the
compound.
The
Agency
would
want
to
know
if
any
VOC
exemption
led
to
increased
use
of
a
compound
with
significant
toxic
properties.
The
EPA
is
not
finally
resolving
issues
concerning
non­
ozone
environmental
impacts
of
VOC
exemptions
in
this
notice,
but
is
considering
issuing
a
future
policy
statement
concerning
such
issues.

Comments
About
Detrimental
Reliance
Comment
39.
Several
commenters
state
that
companies
have
relied
on
past
EPA
statements
regarding
acceptability
of
the
per
gram
basis
for
comparing
a
compound's
reactivity
to
that
of
ethane.
According
to
these
commenters,
companies
may
have
spent
considerable
amounts
of
resources
in
research
based
on
this
EPA
policy
.
[
Advance
Chemical
Dist.
Inc
(
II­
D­
07),
Exxon
Chemical
Company
(
II­
D­
16),
Lyondell
(
II­
D­
25),
Penreco
and
Printing
Industries
of
America
(
II­
D­
18),
Chemical
Specialities
Manufacturers
Association
(
II­
D­
23)].
Lyondell
specifically
states
that
it
substantially
relied
on
the
EPA's
past
statements
regarding
the
per
gram
approach.[
Lyondell
Chemical
Company
(
II­
D­
25)].
According
to
one
commenter,
the
EPA
is
departing
from
past
practice
without
a
rational
justification,
which
raises
significant
procedural
concerns.
[
The
Aluminum
Association
of
America
(
II­
D­
18)].
Occidental,
on
the
other
hand,
contends
that
EPA
has
not
articulated
a
defensible
legal
standard
under
the
Clean
Air
Act
for
addressing
the
pending
petitions,
and
that
there
is
no
place
in
the
standard
setting
process
for
consideration
of
business
development
costs
in
regulating
chemicals
that
contribute
to
the
formation
of
ozone.
Occidental
states
that
the
Clean
Air
Act
does
not
allow
the
Administrator
to
use
her
discretion
to
exclude
a
compound
from
regulation
based
on
whether
a
company
spends
a
little
or
a
lot
of
money
in
developing
that
chemical
for
market.
Occidental
also
contends
that
the
notice
is
too
vague
about
how
the
significant
reliance
criterion
will
be
applied
in
the
future.
In
addition,
according
to
Occidental,
EPA
ignored
"
the
significant
reliance"
argument
when
it
exempted
acetone.
A
company
commenting
on
that
action
said
it
had
made
business
investments
in
developing
products
used
for
industrial
parts
cleaning
which
could
be
used
in
place
of
acetone,
which
was
then
controlled
as
a
VOC.
If
acetone
were
exempted,
the
company
said
it
would
lose
its
business
investment
and
future
profits.
The
EPA
recognized
that
this
might
be
the
case,
but
went
ahead
with
the
acetone
exemption
anyway.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
These
comments
resulted
from
EPA's
statement
in
the
September
39,
1999
proposal
that
EPA
would
evaluate
future
exemption
petitions
only
on
a
per
mole
basis,
but
would
grandfather
already
received
petitions
for
evaluation
on
either
a
per
gram
or
per
mole
basis,
if
the
petition
met
certain
conditions,
such
as
furthering
the
purpose
of
the
Clean
Air
Act
and
demonstrating
significant
detrimental
reliance.
In
this
final
rule,
EPA
is
exempting
TBAC
under
the
existing
VOC
exemption
policy,
on
a
per
gram
basis,
and
is
not
changing
the
VOC
exemption
policy
at
this
time.
Thus,
today's
action
does
not
involve
grandfathering.
The
EPA
notes,
however,
that
reliance
by
a
petitioner
on
a
past
policy,
while
an
important
consideration,
is
not
in
and
of
itself
a
sufficient
reason
to
grandfather
a
VOC
exemption
petition.
22
Comment
40.
A
commenter
asks
why
EPA
is
considering
costs
to
the
petitioner
(
who
spent
money
in
research
after
relying
on
EPA
policy
statements
on
per
gram
basis)
while
ignoring
millions
of
dollars
spent
by
the
paint
industry
and
coatings
users
to
switch
to
low
VOC
coatings
in
reliance
on
past
EPA
regulations
restricting
emissions
of
these
VOC
compounds.
According
to
this
commenter,
much
of
this
work
will
be
ignored
if
users
are
allowed
to
return
to
solvent
based
coatings
with
unlimited
solvent
content.
[
James
C.
Berry
(
II­
D­
30)].

Response:
Industry
has
made
large
expenditures
in
developing
low
solvent
coatings
over
the
years
since
the
mid­
1970s
when
specific
emission
limitations
for
industrial
paints
began
to
be
recommended
on
a
national
basis.
However,
no
companies
which
have
formulated
low
solvent
coatings
commented
in
opposition
to
the
granting
of
the
exemption
for
TBAC.
In
fact,
the
National
Paint
and
Coatings
Association
(
NPCA),
which
represents
many
paint
companies
which
have
developed
low
solvent
coatings,
wrote
in
support
of
the
exemption.
The
NPCA
said,
"
The
wider
the
spectrum
of
such
exempt
materials,
the
more
opportunities
exist
for
reformulating
a
fuller
range
of
cost
effective
lower
VOC
coatings."
[
NPCA
(
II­
D­
22)].
As
stated
above,
today's
action
does
not
involve
grandfathering,
and
EPA
is
no
longer
considering
the
costs
to
the
petitioner.
The
EPA
notes,
however,
that
one
problem
with
basing
a
grandfathering
approach
solely
on
costs
incurred
by
the
petitioner
is
that
such
an
approach
does
not
take
into
account
costs
incurred
by
others
in
the
industry.

Comment
41.
According
to
Occidental,
most,
if
not
all,
petitioners
had
notice
nearly
two
years
ago
of
EPA's
judgement
regarding
the
impropriety
of
using
the
gram
comparison
rather
than
the
molar
comparison
for
assessing
its
ozone
forming
potential.
[
Occidental
Chemical
Corporation
(
IID
29)].

Response:
The
EPA
said
in
the
August
25,
1997
(
62
FR
44926)
proposal
to
exempt
methyl
acetate
that
it
was
considering
the
proposal
on
a
per
mole
as
well
as
on
a
per
gram
basis.
Also,
EPA
speakers
made
public
statements
at
a
May
1998
Photochemical
Reactivity
Workshop
to
the
effect
that
a
review
of
the
original
1977
experimental
work
used
to
select
ethane
as
the
exemption
cut­
off
showed
that
the
experiments
were
done
on
a
molar
basis,
and
that
comparisons
to
ethane
on
a
weight
basis
may
not
be
valid.
However,
as
stated
in
response
to
Comment
15,
these
comments
were
not
intended
as
official
Agency
policy
statements.
The
EPA
is
considering
these
issues
as
part
of
a
review
of
the
overall
exemption
policy
but
has
not
yet
changed
its
policy.

Comment
42.
The
notice
is
inconsistent
in
that
on
page
52734
it
says
the
Agency
will
no
longer
utilize
the
weight­
based
comparison
and
on
that
same
page
says
that
for
petitions
listed
in
Table
1,
it
will
consider
the
"
significant
reliance"
demonstrated
by
each
petitioner
on
a
case­
by­
case
basis.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
The
EPA
proposed
to
change
its
policy
to
grandfather
the
Table
1
petitions
if
they
met
certain
criteria.
However,
the
EPA
is
not
changing
its
policy
at
this
time.
Thus,
grandfathering
is
no
longer
at
issue.

Comment
43.
Lyondell
refers
to
a
letter
from
a
representative
of
ARCO
(
now
Lyondell)
to
a
research
scientist
at
EPA.
In
this
letter,
ARCO
presents
reactivity
data
for
TBAC
on
both
a
per
23
gram
and
per
mole
basis.
ARCO
asserts
that
in
a
subsequent
telephone
conversation
this
scientist
said
it
appears
that
TBAC
would
qualify
for
exemption
on
a
per
gram
basis.
[
Lyondell
Chemical
Company
(
II­
D­
25)].

Response:
The
ARCO
letter
to
EPA
research
scientist
(
I­
C­
01)
and
the
follow
up
letter
that
the
scientist
wrote
to
ARCO
subsequent
to
the
telephone
conversation
(
I­
B­
01)
are
both
in
the
docket
for
this
rule.
The
EPA
scientist
does
not
mention
in
his
letter
that
TBAC
may
be
eligible
for
exemption
on
a
per
gram
basis,
but
rather
advises
the
ARCO
representative
to
discuss
the
TBAC
issue
with
an
EPA
regulatory
policy
official.

Comment
44.
According
to
Occidental,
the
reference
in
the
1995
§
183(
e)
Consumer
Products
Report
to
Congress
regarding
use
of
the
gram
basis
for
exemption
does
not
establish
a
strong
basis
for
the
petitioner's
detrimental
reliance.
That
reference
refers
to
the
protocol
"
presently
favored."
Occidental
says
that
in
using
that
phrase,
EPA
was
conveying
that
it
was
re­
evaluating
its
position.
The
Report
to
Congress
statement
says
that
the
protocol
favored
by
EPA
for
VOC
reactivity
testing
calls
for
a
measurement
of
the
species
k
OH
reactivity
relative
to
that
of
ethane.
TBAC
has
a
k
OH
value
larger
than
that
of
ethane.
On
this
basis,
EPA
should
not
have
further
evaluated
TBAC.
[
Occidental
Chemical
Corporation
(
II­
D­
29)].

Response:
The
183(
e)
report
to
Congress
statement
did
refer
to
k
OH
reactivity,
but
said
that
a
per
gram
basis
was
preferred
by
one
office
of
EPA,
although
it
did
not
tell
how
k
OH
would
be
expressed
on
a
per
gram
basis.
The
usual
k
OH
units
are
on
a
molecular
basis.
The
statement
in
the
footnote
indicated
that
this
approach
was
"
presently
favored
­­
but
not
officially
endorsed"
which
clearly
indicated
that
this
was
not
meant
to
be
a
definitive
policy
statement.
At
any
rate,
EPA
is
not
using
a
"
grandfathering"
analysis
as
the
basis
for
the
TBAC
exemption
final
rule.
