Draft
6­
30­
04;
Do
not
quote
or
cite
GUIDANCE
ON
LIMITING
NITROGEN
OXIDES
REQUIREMENTS
RELATED
TO
8­
HOUR
OZONE
IMPLEMENTATION
Draft
July
2004
U.
S.
Environmental
Protection
Agency
Office
of
Air
Quality
Planning
and
Standards
Research
Triangle
Park,
NC
27711
Draft
6­
30­
04;
Do
not
quote
or
cite
2
GUIDANCE
ON
LIMITING
NITROGEN
OXIDES
REQUIREMENTS
RELATED
TO
8­
HOUR
OZONE
IMPLEMENTATION
CONTENTS
CHAPTERS
1
INTRODUCTION
1.1
General
1.2
Section
182(
f)
1.3
Nitrogen
Oxides
Requirements
1.4
Section
185B
Study
1.5
Application
of
Section
182(
f)
Requirements
1.6
Organization
of
this
Document
2
ADMINISTRATIVE
PROCEDURES
2.1
Processing
with
the
State
Implementation
Plan
(
SIP)
Revision
2.2
Petition
2.3
Interface
with
the
SIP
2.4
Timing
2.5
Areas
with
a
1­
Hour
Ozone
NO
x
Exemption
3
NET
AIR
QUALITY
BENEFIT
3.1
Demonstration
3.2
Factors
A.
Ozone
Nonattainment
Areas
B.
Areas
Nonattainment
for
both
Ozone
and
Nitrogen
Dioxide
C.
Areas
Nonattainment
for
both
Ozone
and
Particulate
Matter
D.
Areas
Nonattainment
for
Ozone
and
Carbon
Monoxide,
Lead
or
Sulfur
Dioxide
E.
Secondary
Factors
3.3
Geographic
Scope
3.4
Scenarios
3.5
Sources
4
CONTRIBUTE
TO
ATTAINMENT
4.1
Demonstration
4.2
Geographic
Scope
4.3
Applicability
to
Areas
Monitoring
Attainment
5
NET
OZONE
AIR
QUALITY
BENEFIT
5.1
Demonstration
5.2
Factors
5.3
Attainment/
Unclassified
Portions
6
EXCESS
EMISSIONS
REDUCTIONS
6.1
General
Draft
6­
30­
04;
Do
not
quote
or
cite
3
6.2
Demonstration
7
MODELING
TECHNIQUES
7.1
Photochemical
Grid
Modeling
7.2
Regional
Modeling
8
EMISSIONS
ANALYSIS
8.1
General
8.2
Years
to
Analyze
8.3
Scenarios
to
Compare
8.4
Consistency
with
the
SIP
8.5
New
Source
Review
1See
57
FR
55622
("
Nitrogen
Oxides
Supplement
to
the
General
Preamble,"
published
November
25,
1992).

2Guideline
for
Determining
the
Applicability
of
Nitrogen
Oxide
Requirements
under
Section
182(
f),"
from
John
S.
Seitz,
Director,
Office
of
Air
Quality
Planning
and
Standards,
to
the
Regional
Division
Directors,
December
16,
1993.

3"
Section
182(
f)
Nitrogen
Oxides
(
NO
x)
ExemptionsBRevised
Process
and
Criteria,"
memorandum
from
John
S.
Seitz,
Director,
Office
of
Air
Quality
Planning
and
Standards,
to
the
Regional
Division
Directors,
May
27,
1994;
and
"
Section
182(
f)
Nitrogen
Oxides
(
NO
x)
Exemptions­­
Revised
Process
and
Criteria,"
memorandum
from
John
S.
Seitz,
Director,
Office
of
Air
Quality
Planning
and
Standards,
to
the
Regional
Division
Directors,
February
8,
1995.
CHAPTER
1
INTRODUCTION
1.1
General
In
subpart
2
of
part
D
of
the
Clean
Air
Act
(
CAA),
as
amended
in
1990,
section
182(
f)
requires
States
to
apply
the
same
requirements
to
major
stationary
sources
of
nitrogen
oxides
(
NOx)
as
are
applied
to
major
stationary
sources
of
volatile
organic
compounds
(
VOC).
These
requirements
are
reasonably
available
control
technology
(
RACT)
and
new
source
review
(
NSR)
for
major
stationary
sources
in
certain
ozone
nonattainment
areas
and
throughout
States
in
the
Ozone
Transport
Region.
1
In
addition,
section
182(
f)
specifies
circumstances
under
which
these
NOx
requirements
would
be
limited
or
would
not
apply
(
NOx
exemption).
Further,
as
a
result
of
rulemaking,
areas
granted
a
NOx
exemption
under
section
182(
f)
may
be
exempt
from
certain
NOx
requirements
related
to
motor
vehicle
inspection
and
maintenance,
operating
permits,
and
general
and
transportation
conformity.

In
1993,
EPA
issued
a
guidance
document
for
application
of
the
section
182(
f)
provisions
with
respect
to
the
1­
hour
ozone
standard.
2
The
NO
x
exemption
guidance
for
the
1­
hour
ozone
standard,
as
revised,
3
continues
to
apply.
The
1­
hour
guidance
should
be
applied
independently
from
the
guidance
for
the
8­
hour
ozone
standard.

In
1997,
EPA
established
the
8­
hour
ozone
standard.
On
June
2,
2003,
EPA
proposed
rules
to
implement
the
8­
hour
ozone
standard
(
68
FR
32802).
The
EPA
proposed
to
extend
to
subpart
1
areas
the
NOx
RACT
and
NSR
requirements
which
apply
to
major
Draft
6­
30­
04;
Do
not
quote
or
cite
2
4With
respect
to
NSR,
the
EPA
recognized
that
the
terms
of
existing
NSR
regulations
should
be
adequate
to
cover
NOx
where
it
is
considered
a
precursor
to
the
formation
of
ozone,
but
proposed
to
codify
NOx
as
an
ozone
precursor
in
order
to
be
completely
clear.
68
FR
32846.
stationary
sources
in
subpart
2
nonattainment
areas
and
throughout
an
Ozone
Transport
Region.
4
The
EPA
also
proposed
to
establish
NOx
exemption
provisions
for
the
8­
hour
ozone
standard
that
reflect
the
same
concepts
as
the
existing
guidance
for
the
1­
hour
ozone
standard.

Decreases
in
NOx
emissions
generally
reduce
ozone
levels
and
provide
significant
ozone­
related
health
benefits.
At
the
local
level,
however,
this
is
not
always
the
case.
Due
to
the
complex
photochemistry
of
ozone
production,
emissions
of
NOx
lead
to
both
the
formation
and
destruction
of
ozone
(
O3).
In
sunlight
free
radicals
oxidize
NO
to
NO2
and
the
NO2
reacts
with
sunlight
to
recreate
NO
and
to
produce
O3.
The
resulting
O3
concentration
depends,
in
part,
on
the
relative
quantities
of
NOx
(
NO
+
NO2),
VOC,
and
free
radicals
(
e.
g.,
OH).
Some
combination
of
VOC
and
NOx
is
optimum
at
producing
O3.

In
areas
with
large
emissions
of
NO
relative
to
VOC,
the
reaction
between
emitted
NO
and
existing
O3
removes
some
O3
(
forming
NO2
and
O2).
In
addition,
a
portion
of
the
NO2
formed
reacts
with
OH
to
produce
nitric
acid,
a
form
of
nitrogen
that
does
not
create
O3.
In
these
cases,
decreases
in
NOx
emissions
result
in
a
local
increase
in
O3
concentrations
(
NOx
disbenefit).
This
effect
is
usually
short­
lived
(
local)
and
much
of
the
NO2
formed
from
the
reaction
between
NO
and
O3
leads
to
formation
of
O3
later
(
i.
e.,
further
downwind).
The
ozone
increases
that
can
result
from
NOx
emissions
reductions
in
these
localized
areas
are
generally
limited
to
small
regions
within
specific
urban
cores
and
are
surrounded
by
larger
regions
in
which
NOx
control
is
beneficial.

This
potential
NOx
disbenefit
resulted
in
Congress
including
NOx
exemption
provisions
in
subpart
2,
section
182(
f).
The
EPA
believes
the
NOx
exemption
provisions
are
a
prudent
safeguard
to
avoid
unnecessary
emissions
reductions
and
should
be
extended
into
subpart
1
areas.
Therefore,
in
the
8­
hour
ozone
implementation
rule
EPA
proposed
to
establish
NOx
exemption
provisions
for
areas
subject
to
subpart
1
as
well
as
subpart
2.
The
EPA
proposed
that
the
concepts
contained
in
the
existing
1­
Draft
6­
30­
04;
Do
not
quote
or
cite
3
5The
EPA's
primary
guidance
regarding
section
182(
f)
is
contained
in
the
"
Guideline
for
Determining
the
Applicability
of
Nitrogen
Oxide
Requirements
under
Section
182(
f),"
issued
by
John
S.
Seitz,
Director,
Office
of
Air
Quality
Planning
and
Standards,
to
the
Regional
Division
Directors,
December
16,
1993.

6
Ozone
Transport
Assessment
Group,
OTAG
Final
Report,
1997.

7
NARSTO,
An
Assessment
of
Tropospheric
Ozone
Pollution
­
A
North
American
Perspective,
July
2000.

8
USEPA,
The
Ozone
Report:
Measuring
Progress
through
2003,
April
2004.
hour
ozone
guidance5
regarding
section
182(
f)
would
apply
for
the
8­
hour
ozone
program
under
subparts
1
and
2
as
described
in
this
document.

While
localized
ozone
increases
can
result
from
NOx
reductions,
it
should
be
noted
that
the
most
recent
authoritative
assessments
of
regional
ozone
control
approaches6,
7
have
concluded
that
a
NOx
control
strategy
would
be
most
effective
for
reducing
regional
scale
ozone
and
ozone
transport,
whereas
VOC
reductions
are
most
effective
in
more
dense
urbanized
areas.
As
a
result,
EPA
has
proposed
or
promulgated
several
regulatory
requirements
over
the
past
decade
designed,
in
part,
to
reduce
regional
NOx
emissions:
rules
from
the
Acid
Rain
Program,
multiple
Federal
motor
vehicle
and
off­
road
engine
standards,
the
regional
NOx
SIP
Call
Rule,
and
the
recently
proposed
Clean
Air
Interstate
Rule.
Over
time
these
rules
are
expected
to
reduce
the
magnitude
and
the
geographic
extent
of
the
nation's
8­
hour
ozone
problem.
In
addition,
EPA
has
recently
concluded8
that
improvements
in
ozone
air
quality
over
the
eastern
United
States
since
the
mid­
1990s
have
coincided
with
continued
decreases
in
NOx
emissions,
together
with
local
VOC
control
programs.

This
document
describes
EPA's
preliminary
views
on
how
EPA
would
determine
that
the
NOx
requirements
would
be
limited
or
would
not
apply
for
the
8­
hour
ozone
program
under
subparts
1
and
2.
Although
this
document
includes
various
statements
that
States
or
petitioners
must
take
certain
actions,
these
statements
are
guidance
made
pursuant
to
EPA's
preliminary
interpretations,
and
thus
do
not
bind
the
States
and
the
public
as
a
matter
of
law.
The
EPA's
interpretations
will
provide
a
basis
for
subsequent
EPA
approval
or
disapproval
of
requests
for
exemption
Draft
6­
30­
04;
Do
not
quote
or
cite
4
from
the
NOx
requirements.
This
document
does
not
impose
binding,
enforceable
requirements
on
any
party,
nor
does
it
assure
that
EPA
may
approve
all
instances
of
its
application,
and
thus
the
guidance
may
not
apply
to
a
particular
situation
based
upon
the
circumstances
presented.
EPA
retains
the
discretion
to
adopt
approaches
on
a
case­
by­
case
basis
that
differ
from
this
guidance
where
appropriate.

Any
decisions
by
EPA
regarding
a
particular
demonstration
pursuant
to
section
182(
f)
will
only
be
made
following
notice
and
opportunity
for
public
review
and
comment.
Therefore,
interested
parties
are
free
to
raise
questions
and
objections
about
the
appropriateness
of
the
application
of
this
guidance
to
a
particular
situation;
EPA
will
consider
whether
or
not
the
guidelines
set
forth
in
this
document
are
appropriate
in
that
situation.
This
guidance
is
a
living
document
and
may
be
revised
periodically
without
public
notice.
The
EPA
welcomes
public
comments
on
this
document
at
any
time
and
will
consider
those
comments
in
any
future
revisions
of
this
guidance
document.
Readers
of
this
document
are
cautioned
not
to
regard
statements
recommending
the
use
of
certain
procedures
or
defaults
as
either
precluding
other
procedures
or
information
or
providing
guarantees
that
using
these
procedures
or
defaults
will
result
in
actions
that
are
fully
approvable.
As
noted
above,
EPA
cannot
assure
that
actions
based
upon
this
guidance
will
be
fully
approvable
in
all
instances,
and
all
final
actions
may
only
be
taken
following
notice
and
opportunity
for
public
comment.

1.2
Section
182(
f)

Section
182(
f)
of
the
Clean
Air
Act
reads
as
follows:

NO
x
Requirements.
B(
1)
The
plan
provisions
required
under
this
subpart
for
major
stationary
sources
of
volatile
organic
compounds
shall
also
apply
to
major
stationary
sources
(
as
defined
in
section
302
and
subsections
(
c),
(
d),
and
(
e)
of
this
section)
of
oxides
of
nitrogen.
This
subsection
shall
not
apply
in
the
case
of
oxides
of
nitrogen
for
those
sources
for
which
the
Administrator
determines
(
when
the
Administrator
approves
a
plan
or
plan
revision)
that
net
air
quality
benefits
are
greater
in
the
absence
of
reductions
of
oxides
of
nitrogen
from
the
sources
concerned.
This
subsection
shall
also
not
apply
in
the
case
of
oxides
of
nitrogen
for)
(
A)
nonattainment
areas
not
within
an
ozone
transport
region
under
section
184
if
the
Administrator
determines
(
when
the
Administrator
approves
a
plan
or
plan
revision)
that
additional
reductions
of
oxides
of
nitrogen
would
not
contribute
to
attainment
of
the
national
ambient
air
quality
standard
for
ozone
in
the
area,
or
Draft
6­
30­
04;
Do
not
quote
or
cite
5
(
B)
nonattainment
areas
within
such
an
ozone
transport
region
if
the
Administrator
determines
(
when
the
Administrator
approves
a
plan
or
plan
revision)
that
additional
reductions
of
oxides
of
nitrogen
would
not
produce
net
ozone
air
quality
benefits
in
such
region.
The
Administrator
shall,
in
the
Administrator's
determinations,
consider
the
study
required
under
section
185B.
(
2)(
A)
If
the
Administrator
determines
that
excess
reductions
in
emissions
of
NO
x
would
be
achieved
under
paragraph
(
1),
the
Administrator
may
limit
the
application
of
paragraph
(
1)
to
the
extent
necessary
to
avoid
achieving
such
excess
reductions.
(
B)
For
purposes
of
this
paragraph,
excess
reductions
in
emissions
of
NO
x
are
emission
reductions
for
which
the
Administrator
determines
that
net
air
quality
benefits
are
greater
in
the
absence
of
such
reductions.
Alternatively,
for
purposes
of
this
paragraph,
excess
reductions
in
emissions
of
NO
x
are,
for)
(
i)
nonattainment
areas
not
within
an
ozone
transport
region
under
section
184,
emission
reductions
that
the
Administrator
determines
would
not
contribute
to
attainment
of
the
national
ambient
air
quality
standard
for
ozone
in
the
area,
or
(
ii)
nonattainment
areas
within
such
ozone
transport
region,
emission
reductions
that
the
Administrator
determines
would
not
produce
net
ozone
air
quality
benefits
in
such
region.
(
3)
At
any
time
after
the
final
report
under
section
185B
is
submitted
to
Congress,
a
person
may
petition
the
Administrator
for
a
determination
under
paragraph
(
1)
or
(
2)
with
respect
to
any
nonattainment
area
or
any
ozone
transport
region
under
section
184.
The
Administrator
shall
grant
or
deny
such
petition
within
6
months
after
its
filing
with
the
Administrator.

1.3
The
NO
x
Requirements
The
NOx
requirements
for
NSR
and
RACT
are
described
in
EPA's
proposed
rule
to
implement
the
8­
hour
ozone
standard
(
68
FR
32810).
Where
EPA
grants
an
areawide
exemption,
the
NO
x
RACT
and
NSR
requirements
may
not
apply.
In
addition,
areas
granted
a
NOx
exemption
may
be
exempt
from
certain
Federal
requirements
related
to
Title
V
operating
permits,
motor
vehicle
I/
M,
and
general
and
transportation
conformity.

As
stated
in
EPA's
inspection
and
maintenance
(
40
CFR
51.351(
d))
and
conformity
rules
(
40
CFR
93.119(
f)(
2)
for
transportation
rules
and
40
CFR
93.152
for
general
rules),
certain
NO
x
requirements
do
not
apply
where
EPA
granted
an
areawide
exemption
under
section
182(
f).
Pursuant
to
40
CFR
Part
70.2
(
subparagraph
(
3)(
i)
under
the
"
major
source"
definition),
the
major
source
threshold
for
federal
operating
permit
programs
would
be
defined
as
100
tons
per
year
in
areas
covered
by
a
NO
x
exemption.
These
exemptions
automatically
apply;
i.
e.,
a
State
Draft
6­
30­
04;
Do
not
quote
or
cite
6
does
not
need
to
request
the
application
or
granting
of
the
inspection/
maintenance
or
conformity
exemptions.
However,
a
State
may
request
that
an
exemption
apply
for
limited
purposes.

1.4
Section
185B
Study
Under
section
185B,
the
Administrator,
in
conjunction
with
the
National
Academy
of
Sciences
(
NAS),
conducted
a
study
on
the
role
of
ozone
precursors
in
tropospheric
ozone
formation.
The
NAS
report,
Rethinking
the
Ozone
Problem
in
Urban
and
Regional
Air
Pollution,
was
completed
in
December
1991.
The
final
section
185B
study
incorporated
this
NAS
report
along
with
an
EPA
report
addressing
the
availability
and
extent
of
NO
x
controls.
The
section
185B
study
examined
the
role
of
NOx
and
VOC
emissions,
the
extent
to
which
NOx
reductions
may
contribute
or
be
counterproductive
to
achieving
attainment
in
different
nonattainment
areas,
the
sensitivity
of
ozone
to
the
control
of
NOx,
the
availability
and
extent
of
controls
for
NOx,
the
role
of
biogenic
VOC
emissions,
and
the
basic
information
required
for
air
quality
models.
The
final
study
was
submitted
to
Congress
on
July
30,
1993.
In
making
a
determination
under
section
182(
f)
that
the
NO
x
requirements
do
not
apply,
or
may
be
limited,
the
EPA
must
consider
the
section
185B
study.
This
document,
"
Guidance
on
Limiting
Nitrogen
Oxides
Requirements
Related
to
8­
Hour
Ozone
Implementation,"
includes
consideration
of
the
section
185B
study.

1.5
Application
of
Section
182(
f)
Requirements
Section
182(
f)(
1)
provides
that
the
new
NO
x
requirements
shall
not
apply
if
the
Administrator
determines
that
any
one
of
the
following
tests
is
met:

(
1)
in
any
area,
the
net
air
quality
benefits
are
greater
in
the
absence
of
NOx
reductions
from
the
sources
concerned;

(
2)
in
nonattainment
areas
not
within
an
ozone
transport
region,
additional
NOx
reductions
would
not
contribute
to
ozone
attainment
in
the
area;
or
(
3)
in
nonattainment
areas
within
an
ozone
transport
region,
additional
NOx
reductions
would
not
produce
net
ozone
air
quality
benefits
in
the
transport
region.

Further,
section
182(
f)(
2)
states
that
the
application
of
the
new
NO
x
requirements
may
be
limited
to
the
extent
necessary
to
avoid
"
excess
reductions"
of
NO
x
as
determined
by
applying
tests
similar
to
tests
(
1)­(
3)
above.
Draft
6­
30­
04;
Do
not
quote
or
cite
7
As
described
later
in
this
document,
the
"
net
air
quality
benefits"
test
and
the
"
excess
reductions"
provision
may
be
applied
in
an
ozone
transport
region
or
outside
the
transport
region;
the
"
contribute
to
attainment"
test
may
only
be
applied
outside
of
an
ozone
transport
region;
and
the
"
net
ozone
benefits"
test
may
only
be
applied
within
an
ozone
transport
region.
Where
any
one
of
the
tests
is
met
(
even
if
another
test
failed),
the
section
182(
f)
NO
x
requirements
would
not
apply
or,
under
the
excess
reductions
provision,
a
portion
of
these
requirements
would
not
apply.

As
discussed
in
section
1.1
above,
EPA
believes
the
same
concepts
in
section
182(
f)
of
subpart
2
should
be
extended
to
areas
subject
to
subpart
1
requirements
for
purposes
of
the
8­
hour
ozone
standard.
Thus,
while
discussion
in
this
document
focuses
on
the
language
in
section
182(
f),
the
reader
should
be
aware
that
the
guidance
is
intended
to
apply
equally
to
subpart
1
and
subpart
2
areas.

1.6
Organization
of
this
Document
Chapter
1,
above,
provides
an
introduction
to
the
NO
x
exemption
provisions.
In
chapter
2,
procedural
aspects
related
to
a
request
for
a
NO
x
exemption
are
covered.
The
"
net
air
quality
benefits,"
"
contribute
to
attainment,"
and
"
net
ozone
benefits"
tests
are
described
in
detail
in
chapters
3­
5.
The
"
excess
reductions"
provision
is
discussed
in
chapter
6.
Chapters
7­
8
provide
technical
information
related
to
modeling
techniques
and
emissions
analyses
that
may
be
carried
out
to
support
a
NO
x
exemption
request.
Draft
6­
30­
04;
Do
not
quote
or
cite
8
CHAPTER
2
ADMINISTRATIVE
PROCEDURES
2.1
Processing
with
the
State
Implementation
Plan
(
SIP)
Revision
A
State
may,
at
any
time,
demonstrate
to
the
Administrator
that
some
or
all
of
the
NO
x
requirements
listed
in
section
1.2
of
this
document
should
not
apply.
For
example,
a
State
may
submit
a
demonstration
along
with,
or
as
a
revision
to,
the
SIP
at
the
time
NO
x
RACT
rules
are
due.
The
State's
NO
x
exemption
demonstration
is
not
required
to
be
a
SIP
revision
itself.

The
EPA
will
approve
or
disapprove
the
State's
NO
x
exemption
demonstration
when
the
Administrator
approves
a
plan
or
plan
revision.
The
EPA
will
consider
the
section
185B
report
and
will
base
its
decision
on
the
demonstration
and
supporting
information
provided
by
the
State.
Such
demonstration
and
information
should
be
in
sufficient
detail
for
EPA
to
determine
that
the
exemption
request
is
consistent
with
the
guidance
contained
in
this
document.
The
EPA
encourages
the
States
to
consult
with
the
appropriate
EPA
Regional
Office
during
the
development
of
the
exemption
request.
This
is
necessary
to
ensure
that
the
documentation
provided
by
the
State
is
likely
to
be
approved
and
that
any
required
rules
can
be
adopted
in
a
timely
manner.

2.2
Petition
Section
182(
f)(
3)
provides
that
a
person
(
including
a
State)
may
petition
the
Administrator
for
a
NOx
exemption
at
any
time
after
the
final
section
185B
report
is
submitted
to
Congress.
The
petition
may
be
made
with
respect
to
any
nonattainment
area
or
any
ozone
transport
region.
The
EPA
is
required
to
grant
or
deny
a
section
182(
f)
petition
within
6
months
after
its
filing.

Since
an
individual
petition
is
likely
to
affect
the
SIP
planning
process
which
is
primarily
a
State
responsibility,
EPA
believes
it
is
reasonable
to
require
the
petitioner
to
provide
a
copy
of
the
petition
and
demonstration
to
the
State
or
States
which
have
jurisdiction
over
the
source
or
sources
covered
by
the
petition
at
the
same
time
it
is
submitted
to
the
Administrator
(
where
a
petition
is
being
submitted
by
a
person
other
than
the
State
itself).
Where
additional
States
may
be
affected
by
the
petition,
the
State
receiving
the
petition
should
coordinate
with
the
other
States
as
necessary.
In
some
cases
there
may
be
multiple
petitions
for
a
given
area.
In
other
cases
a
single
petition
may
have
multi­
State
implications.
The
EPA
will
provide
the
State(
s)
a
3­
month
period
to
make
a
recommendation
to
EPA
regarding
the
petition.
This
3­
month
period
will
run
concurrently
with
the
6­
month
review
period
required
under
section
182(
f)(
3).
The
petitioner
should
submit
the
petition
and
Draft
6­
30­
04;
Do
not
quote
or
cite
9
demonstration
to
the
Administrator
through
the
appropriate
EPA
Regional
Office.

The
EPA
encourages
any
petitioner
to
consult
with
the
State
air
quality
agency
and
the
appropriate
EPA
Regional
Office
during
the
development
of
an
exemption
request.
This
is
necessary
to
ensure
that
the
documentation
provided
(
1)
meets
EPA
guidance,
(
2)
does
not
conflict
with
similar
analyses
by
the
State,
and
(
3)
is
likely
to
be
accepted
by
the
State
and
EPA.
The
EPA's
decision
to
grant
or
deny
a
petition
will
include
consideration
of
the
section
185B
report
and
will
be
based
on
the
demonstration
provided
by
the
petitioner,
the
State's
recommendation,
and
the
provisions
of
section
182(
f).
As
noted
above,
this
document
sets
forth
EPA's
preliminary
interpretations
of
the
section
182(
f)
provisions
and
extends
those
concepts
to
subpart
1
areas.

The
EPA
will
provide
notice
of
its
final
action
on
a
petition
and
the
rationale
for
that
action
in
a
letter
to
the
petitioner.
If
EPA
denies
a
petition,
the
petitioner
may
supplement
or
revise
the
original
petition
at
a
later
date.
If
EPA
grants
a
petition,
the
NOx
requirements
or
portions
of
those
requirements,
would
no
longer
apply
to
those
sources
or
areas,
as
described
in
EPA's
approval
action.
Since
EPA
approval
of
an
exemption
request
would
change
SIP
requirements,
EPA
would
conduct
notice
and
comment
rulemaking
on
that
request.

2.3
Interface
with
the
SIP
Where
a
petition
for
an
exemption
is
granted
by
EPA
prior
to
adoption
and
submittal
of
the
State's
rules,
the
State
may
simply
choose
not
to
submit
the
NO
x
rules.
If
a
petition
is
granted
after
submittal
of
the
NO
x
rules,
but
prior
to
EPA
approval,
the
State
may
choose
to
withdraw
the
rules
and
preclude
further
EPA
action.
In
a
case
where
a
petition
is
granted
after
EPA
approves
of
the
NOx
rules,
the
SIP
would
need
to
be
modified
through
a
SIP
revision
to
rescind
the
NOx
rules
provided
such
rescission
would
not
interfere
with
attainment
or
reasonable
further
progress
[
section
110(
l)].

Following
application
of
a
photochemical
grid
model
to
support
an
attainment
demonstration,
States
adopt
a
control
strategy
that
provides
for
attainment
as
expeditiously
as
practicable.
The
selection
of
a
control
strategy
may
result
in
revision
of
the
previously
adopted
rules.
In
some
instances
NOx
RACT
and
NSR
requirements
already
adopted
may
need
to
be
supplemented
with
additional
or
more
advanced
NOx
controls
in
order
for
the
area
to
attain
the
NAAQS.

In
other
cases,
an
area
initially
exempted
may
choose,
based
on
the
new
photochemical
grid
modeling
results,
to
adopt
certain
NOx
reduction
rules
in
order
to
attain
and/
or
meet
reasonable
Draft
6­
30­
04;
Do
not
quote
or
cite
10
further
progress
requirements
through
NOx
substitution.
The
area
would
be
removed
from
"
exempt"
status
since
NO
x
reductions
were
subsequently
found
to
be
beneficial
in
their
ozone
attainment
plan.
Consequently,
the
area
would
have
to
adopt
the
NOx
RACT
and
NSR
rules
except
to
the
extent
modeling
shows
that
the
controls
beyond
those
chosen
are
"
excess
reductions"
(
chapter
6)
or
are
counterproductive
to
the
net
air
quality
(
chapter
3).
Credit
for
NOx
substitution
would
be
granted
only
if
in
accordance
with
the
EPA
guidance.
In
any
event,
these
changes
must
be
submitted
as
a
SIP
revision
and
must
provide
for
attainment
as
expeditiously
as
practicable
and
meet
reasonable
further
progress
requirements.

Alternatively,
for
an
area
that
adopted
the
NOx
RACT
and
NSR
rules
(
i.
e.,
not
exempt),
a
State
may
choose
to
revise
some
or
all
of
those
rules
to
require
less
NOx
stationary
source
controls.
This
action
would
be
based
on
the
application
of
a
photochemical
grid
model
showing
that
the
subject
NOx
controls
result
in
excess
emission
reductions,
as
determined
using
the
section
182(
f)
tests
set
forth
in
this
document.
The
revisions
must
be
submitted
as
a
SIP
revision
and
the
SIP
must
demonstrate
attainment
as
expeditiously
as
practicable.

In
areas
that
are
granted
a
NO
x
exemption
with
respect
to
the
8­
hour
ozone
standard,
States
remain
free
to
adopt
NOx
restrictions
for
other
reasons.
For
example,
a
State
may
determine
that
NO
x
reductions
are
needed
for
purposes
of
ozone
maintenance
planning,
ozone
attainment
in
separate
downwind
nonattainment
areas,
visibility
protection,
particulate
matter
attainment
or
maintenance,
acid
deposition,
or
other
environmental
protection.
The
EPA
could
approve
certain
NO
x
restrictions
in
a
SIP
revision
despite
granting
an
exemption
request,
so
long
as
the
NO
x
restrictions
would
not
interfere
with
meeting
any
applicable
requirement
concerning
attainment
and
reasonable
further
progress
or
any
other
applicable
requirement
of
the
CAA
[
see
section
110(
l)].

Many
of
the
areas
that
are
violating
either
the
8­
hour
ozone
or
PM2.5
NAAQS,
may
be
violating
both
of
these
NAAQS.
Thus,
in
many
cases,
States
will
have
ozone
and
PM2.5
nonattainment
areas
with
overlapping
boundaries.
Requirements
for
regional
haze
apply
to
all
areas.
Each
State
is
responsible
for
developing
SIP
revisions
to
meet
all
the
requirements
relevant
to
each
nonattainment
area
for
each
pollutant
as
well
as
developing
a
regional
haze
plan.
In
some
cases,
ozone
control
measures
may
also
be
useful
for
a
PM2.5
control
strategy
or
a
regional
haze
plan.
Similarly,
controls
for
PM2.5
may
lead
to
reductions
in
ozone
or
regional
haze.
For
example,
considered
in
isolation,
a
metropolitan
area's
ozone
strategy
might
be
based
on
additional
VOC
emissions
reductions;
if
the
area
needs
NOx
reductions
for
Draft
6­
30­
04;
Do
not
quote
or
cite
11
9Section
302(
e)
of
the
Act
defines
the
term
"
person"
to
include
States.
PM2.5
attainment,
however,
an
optimal
approach
might
include
a
more
complex
ozone
strategy
using
both
NOx
and
VOC
reductions.
We
believe
integration
of
ozone
and
PM2.5
attainment
planning
will
reduce
overall
costs
of
meeting
multiple
air
quality
goals.
An
integrated
assessment
of
the
impact
controls
have
on
ozone,
secondary
fine
particles,
and
regional
haze
provides
safeguards
to
ensure
ozone
controls
will
not
preclude
optimal
controls
for
secondary
fine
particles
and
visibility
impairment.
Therefore,
we
encourage
States
conducting
modeling
analyses
for
ozone
to
separately
estimate
effects
of
a
strategy
on
the
following:
mass
associated
with
sulfates,
nitrates,
organic
carbon,
elemental
carbon,
and
all
other
species.

2.4
Timing
Section
182(
f)
contains
few
details
regarding
the
administrative
procedure
for
acting
on
NOx
exemption
requests.
The
absence
of
specific
guidelines
by
Congress
leaves
EPA
with
discretion
to
establish
reasonable
procedures,
consistent
with
the
requirements
of
the
Administrative
Procedure
Act
(
APA).

The
EPA
believes
that
section
182(
f)
sets
up
two
separate
procedures
by
which
the
Agency
may
act
on
NO
x
exemption
requests.
Section
182(
f)(
1)
and
(
2)
direct
that
action
on
NO
x
exemption
determination
requests
should
take
place
"
when
[
EPA]
approves
a
plan
or
plan
revision."
This
language
appears
to
contemplate
that
exemption
requests
submitted
under
these
paragraphs
are
limited
to
States,
since
States
are
the
entities
authorized
under
the
Act
to
submit
plans
or
plan
revisions.
By
contrast,
section
182(
f)(
3)
provides
that
"
person[
s]"
9
may
petition
for
a
NO
x
determination
"
at
any
time"
after
the
ozone
precursor
study
required
under
section
185B
of
the
Act
is
finalized,
and
gives
EPA
a
limit
of
6
months
after
filing
to
grant
or
deny
such
petitions.
Although
section
182(
f)(
3)
references
182(
f)(
1),
there
are
certain
key
differences
in
the
language.
First,
individuals
may
submit
petitions
under
paragraph
(
3)
"
at
any
time"
(
i.
e.,
even
when
there
is
no
plan
revision
from
the
State
pending
at
EPA).
Second,
the
specific
timeframe
for
EPA
action
established
in
paragraph
(
3)
is
substantially
shorter
than
the
timeframe
usually
required
for
States
to
develop
and
for
EPA
to
take
action
on
revisions
to
a
SIP.
These
differences
strongly
suggest
that
Congress
intended
the
process
for
acting
on
personal
petitions
to
be
distinct­­
and
more
expeditious­­
from
the
planrevision
process
intended
under
paragraph
(
1).
Thus,
EPA
believes
that
paragraph
(
3)'
s
reference
to
paragraph
(
1)
encompasses
only
the
substantive
tests
in
paragraph
(
1)
[
and,
by
Draft
6­
30­
04;
Do
not
quote
or
cite
12
extension,
paragraph
(
2)],
not
the
requirement
in
paragraph
(
1)
for
EPA
to
grant
exemptions
only
when
acting
on
plan
revisions.

The
requirements
of
the
APA
apply
with
respect
to
the
type
of
notice
which
must
be
provided
regarding
EPA
action
on
NO
x
exemption
determinations.
Notice­
and­
comment
rulemaking
is
required
by
the
APA
when
EPA
action
involves
not
just
factual,
but
also
policy
and
legal
considerations
that
will
apply
as
a
general
matter
and,
thus,
is
legislative
in
nature.
Conversely,
when
EPA
action
can
properly
be
described
as
party
specific
in
nature,
involving
consideration
of
primarily
factual
evidence,
notice­
and­
comment
rulemaking
is
not
required
by
the
APA.
In
such
a
case,
the
EPA
action
could
consist
of
the
issuance
of
an
order
[
see
5
U.
S.
C.
sections
551(
4)­(
7)
and
553].
Given
these
requirements
of
the
APA,
EPA
believes
that
under
either
of
the
procedures
established
in
section
182(
f),
where
the
request
is
for
an
entire
area
to
be
exempted
from
the
NO
x
requirements,
the
EPA
must
go
through
notice­
and­
comment
rulemaking
to
grant
or
deny
the
petition.
Where
a
petition
is
submitted
for
an
exemption
determination
relating
to
an
individual
source
(
or
group
of
sources)
under
subsection
182(
f)(
3),
EPA
may
grant
or
deny
the
petition
through
an
order
transmitted
by
letter
to
the
affected
source
(
or
sources).
The
EPA
will
also
provide
the
public
with
notice
in
the
Federal
Register
of
the
receipt
and
availability
of
the
petition,
as
well
as
of
the
EPA's
final
determination.

Section
182(
f)(
3)
requires
that
EPA
grant
or
deny
a
petition,
whether
areawide
or
source
specific,
within
6
months
after
its
filing.
Where
the
rulemaking
process
is
followed,
EPA
is
aware
that
the
6­
month
requirement
may
be
infeasible
in
some
cases.
However,
courts
have
ruled
that
even
in
instances,
such
as
the
one
presented
here,
where
a
prescribed
timeframe
for
EPA
action
apparently
conflicts
with
the
requirement
to
provide
the
public
with
adequate
opportunity
for
notice
and
comment,
the
notice
requirement
must
be
met.
Therefore,
EPA
will
process
areawide
exemption
requests
by
rulemaking
as
expeditiously
as
practicable,
with
the
intent
of
meeting
the
6­
month
deadline.

As
noted
earlier,
petitions
submitted
under
section
182(
f)(
3)
are
not
required
to
be
submitted
as
SIP
revisions.
Consequently,
the
State
is
not
required
under
the
Act
to
hold
a
public
hearing
in
order
to
petition
for
an
areawide
NO
x
exemption
determination
[
see
section
110(
a)(
1)
and
(
2)].
For
similar
reasons,
if
the
State
is
submitting
an
areawide
petition
under
subsection
182(
f)(
3),
it
is
unnecessary
to
have
the
Governor
submit
the
petition.
However,
because
of
the
need
for
consistency
with
the
requirements
of
40
CFR
part
58,
EPA
believes
that,
particularly
in
cases
where
the
NO
x
exemption
request
(
including
a
request
for
exemption
from
the
NO
x
requirements
of
the
conformity
rules)
is
based
on
monitoring
data,
if
such
data
Draft
6­
30­
04;
Do
not
quote
or
cite
13
are
contained
in
a
petition
submitted
by
a
person
other
than
the
State,
the
petition
should
be
coordinated
with
the
State
air
agency.

2.5
Areas
with
a
1­
Hour
Ozone
NOx
Exemption
For
areas
that
were
previously
granted
a
NOx
exemption
under
the
1­
hour
ozone
standard
and
request
a
NOx
exemption
under
the
8­
hour
ozone
standard,
EPA
proposed
on
June
2,
2003
that
a
new
approval
action
is
needed.
This
is
necessary
to
allow
for
public
comment,
to
assure
consistency
with
the
exemption
guidance
under
the
8­
hour
standard,
and
to
account
for
any
new
information
that
may
point
to
a
different
conclusion.
For
example,
while
many
areas
received
a
1­
hour
NOx
exemption
in
the
mid­
1990s
on
the
basis
of
having
air
quality
monitoring
data
which
met
the
1­
hour
ozone
standard,
EPA
would
not
grant
a
NOx
exemption
for
the
8­
hour
standard
simply
due
to
that
1­
hour
ozone
data.
Furthermore,
several
areas
that
initially
received
a
NOx
exemption
on
the
basis
of
photochemical
grid
modeling
have
since
revoked
the
exemption
based
on
more
recent
studies
showing
the
necessity
of
NOx
emission
decreases
in
order
to
reach
attainment.
Draft
6­
30­
04;
Do
not
quote
or
cite
14
CHAPTER
3
NET
AIR
QUALITY
BENEFIT
3.1
Demonstration
This
demonstration
applies
to
specific
sources
in
an
ozone
nonattainment
area
or
in
an
ozone
transport
region.
It
must
show
that
NOx
reductions
from
the
sources
seeking
the
exemption
would
be
counter­
productive
overall,
considering
the
net
air
quality
benefits.
Congress
specified
in
this
"
test"
for
specific
sources
a
higher
hurdle
than
in
the
other
tests
for
areawide
exemptions:
the
demonstration
must
show
a
beneficial
impact
from
the
avoidance
of
the
NO
x
controls.
The
procedure
for
this
test
is
to
conduct
dispersion
modeling
analyses
consistent
with
EPA
guidance
with
and
without
NO
x
reductions
at
the
sources
concerned.

3.2
Factors
Unlike
the
tests
described
in
chapters
4
and
5,
this
test
is
not
limited
to
consideration
of
ozone
impacts.
Instead,
this
test
is
based
on
a
broader
set
of
air
quality
impacts.
There
are
many
air
quality
impacts
explicitly
addressed
in
the
CAA,
both
health
and
welfare
related,
that
may
be
directly
or
indirectly
related
to
NO
x
emissions.
These
impacts
include,
for
example,
ozone
and
particulate
matter
formation,
visibility
impairment,
acid
deposition,
air
toxics
formation,
and
nitrogen
deposition
in
nutrient­
sensitive
areas.

Due
to
the
number
and
variety
of
impacts,
it
is
generally
impractical
or
impossible
to
compare
effects
quantitatively
from
one
of
these
factors
to
those
from
another
factor
or
among
several
factors.
For
example,
there
is
no
readily
available
scale
to
use
to
compare
ozone
impacts
with
acid
deposition
impacts
and/
or
visibility
impacts.
Thus,
in
order
to
describe
a
method
for
determining
the
"
net
air
quality
benefit,"
a
distinction
must
be
made
regarding
which
of
the
many
factors
can
and
should
be
analyzed.

Although
"
air
quality
impacts"
could
potentially
be
defined
in
a
very
broad
manner,
EPA
has
concluded
that
the
relevant
air
quality
impacts
must
be
related
directly
to
goals,
standards,
or
mandates
that
are
explicitly
addressed
in
the
CAA.
That
is,
the
test
for
net
air
quality
benefits
must
assure
that
a
decision
to
grant
an
exemption
would
not
interfere
with
the
achievement
of
the
specific
programs
or
goals
mandated
in
the
CAA.
The
key
CAA
programs
related
to
emissions
of
NO
x
are
attainment
and
maintenance
of
the
National
Ambient
Air
Quality
Standards
(
NAAQS)
for
nitrogen
dioxide,
ozone,
and
particulate
matter
and
the
acid
deposition
program.
The
primary
NAAQS
are
set
by
the
Administrator
to
assure
protection
of
the
public
health.
The
Draft
6­
30­
04;
Do
not
quote
or
cite
15
purpose
of
the
acid
deposition
program
is
to
reduce
the
total
atmospheric
loading
of
sulfur
dioxide
and
nitrogen
oxides.

The
CAA
requires
the
primary
NAAQS
to
be
attained
as
expeditiously
as
practicable
and
includes
deadlines
for
designation
of
areas'
attainment
status,
rule
adoption,
submittal
of
control
strategies,
and
attainment
of
the
primary
NAAQS.
To
assure
that
a
NO
x
exemption
would
not
adversely
impact
any
CAA
requirements,
the
impacts
on
attainment
of
the
primary
NAAQS
need
to
be
a
primary
concern
in
the
net
air
quality
benefit
test.
Therefore,
EPA
believes
the
net
air
quality
benefit
test
should
focus
on
protection
of
the
public
health
and
address
the
effect
the
exemption
would
have
on
attainment
of
the
primary
NAAQS
for
the
criteria
pollutants.

Secondary
tests,
as
needed,
can
extend
to
the
(
qualitative
or
quantitative)
consideration
of
other
air
quality
impacts
that
are
explicitly
recognized
in
the
CAA.
These
could
include,
for
example,
the
welfare
effects
which
EPA
has
considered
and
deemed
necessary
to
protect
against
in
setting
secondary
NAAQS
for
the
criteria
pollutants.
A
petitioner
could
also
consider
any
other
air
quality
effects
that
are
explicitly
addressed
in
the
CAA
through
goals,
standards
or
mandates,
for
example,
acid
deposition,
air
toxics,
or
visibility.
While
welfare
related
impacts
address
important
environmental
issues
(
for
example,
atmospheric
deposition
in
nutrient­
sensitive
areas),
the
CAA
generally
does
not
contain
the
same
detailed
set
of
requirements
and
deadlines
as
it
does
for
the
public
health
related
NAAQS.
Further,
EPA
believes
that
granting
a
NO
x
exemption
would
not
relieve,
conflict
with,
or
otherwise
affect
a
source's
obligation
or
ability
to
achieve
NO
x
reductions
consistent
with
the
acid
deposition
requirements.
In
cases
where
NO
x
reductions
from
a
utility
subject
to
section
407
may
be
counterproductive
with
respect
to
local
air
quality,
EPA
expects
the
State
and
utility
would
be
able
to
use
the
emission
averaging
provisions
of
section
407
to
achieve
the
required
NO
x
reductions
at
a
location
where
they
are
not
counterproductive.
The
EPA
believes
the
welfare
related
impacts
should
be
a
secondary
factor
in
the
net
air
quality
benefit
test.

In
all
cases,
the
method
for
consideration
of
the
net
benefits
must
be
related
primarily
to
"
air
quality"
since
section
182(
f)
specifically
requires
a
determination
of
the
"
air
quality"
benefits.
Thus,
simpler
tests,
such
as
a
"
net
emissions"
test,
should
not
be
relied
upon
since
changes
in
emissions
may
not
be
directly
related
to
changes
in
air
quality.
In
general,
air
quality
impacts
can
be
best
determined
by
use
of
air
quality
dispersion
models.

In
order
to
use
air
quality
dispersion
modeling
whenever
possible
and
to
avoid
conflicts
with
other
requirements
of
the
Draft
6­
30­
04;
Do
not
quote
or
cite
16
CAA,
the
methods
described
below
should
be
used
to
determine
the
net
air
quality
benefit
over
an
appropriate
geographic
area
which
includes
the
ozone
nonattainment
areas
encompassing
or
nearby
the
sources
concerned
(
see
section
3.3).
These
methods
include
a
primary
consideration
of
the
primary
NAAQS
air
quality
benefits
and
secondary
consideration
of
other
air
quality
benefits.

A.
Ozone
Nonattainment
Areas
For
areas
that
are
nonattainment
only
for
the
8­
hour
ozone
NAAQS,
the
effects
of
NO
x
reductions
on
ozone
concentrations
should
be
quantified
with
currently
available
air
quality
modeling
techniques
consistent
with
EPA
guidance
(
see
chapter
7).
The
net
air
quality
benefit
should
be
based
on
a
comparison
of
the
geographic
area
where
8­
hour
ozone
concentrations
change
with
and
without
NOx
reductions
from
the
sources
concerned.
Alternatively,
the
change
in
population
exposure
to
ozone
concentrations
may
be
used.
If
the
modeling
shows
a
net
disbenefit
for
ozone,
EPA
could
approve
the
NOx
exemption
request.

B.
Areas
Nonattainment
for
Both
Ozone
and
Nitrogen
Dioxide
For
areas
that
are
nonattainment
for
both
ozone
and
nitrogen
dioxide,
NO
x
reductions
clearly
are
needed
to
provide
for
attainment
of
the
nitrogen
dioxide
standard,
while
either
NO
x
or
VOC
reductions
(
or
both)
might
best
provide
for
attainment
of
the
ozone
standard.
In
such
cases
EPA
would
not
make
a
finding
of
a
net
air
quality
benefit
since
the
CAA
requires
the
NAAQS
for
nitrogen
dioxide
to
be
met
as
expeditiously
as
practicable.

C.
Areas
Nonattainment
for
Both
Ozone
and
Particulate
Matter
Many
of
the
same
factors
affecting
concentrations
of
ozone
also
affect
concentrations
of
secondary
particulate
matter.
For
example,
similarities
exist
in
sources
of
precursors
for
ozone
and
secondary
particulate
matter.
Emissions
of
NOx
may
lead
to
formation
of
nitrates
as
well
as
ozone.
Presence
of
ozone
itself
may
be
an
important
factor
affecting
secondary
particulate
formation.
For
example,
as
ozone
builds
up,
hydroxyl
(
OH)
radicals
do
also
as
a
result
of
equilibrium
reactions
between
ozone,
water
and
OH
in
the
presence
of
sunlight.
Hydroxyl
(
OH)
radicals
are
instrumental
in
oxidizing
gas
phase
SO2
to
sulfuric
acid,
which
is
eventually
absorbed
by
liquid
aerosol
and
converted
to
particulate
sulfate
in
the
presence
of
ammonia.
SO2
also
reacts
with
ozone
and
hydrogen
peroxide
(
a
byproduct
of
photochemistry),
in
the
aqueous
phase,
to
form
particulate
sulfate.
Hydroxyl
radicals
and
NO
are
also
precursors
for
gas
Draft
6­
30­
04;
Do
not
quote
or
cite
17
phase
nitric
acid,
which
is
absorbed
by
liquid
aerosol
and,
in
the
presence
of
ammonia,
leads
to
particulate
nitrate.

Strategies
to
reduce
ozone
can
also
affect
formation
of
secondary
particulate
matter.
Reducing
NOx
emissions
diminishes
one
of
the
precursors
for
nitric
acid
(
i.
e.,
NO2
which
results
from
NO).
Therefore,
in
the
presence
of
sufficient
ammonia,
reducing
NOx
emissions
could
reduce
particulate
nitrate
concentrations.
There
are
also
more
subtle
interfaces
between
strategies
to
reduce
ozone
and
to
reduce
secondary
particulate
matter.
For
example,
reducing
NOx
in
the
presence
of
substantial
particulate
sulfates
and
lack
of
sufficient
ammonia
could
in
some
cases
exacerbate
the
particulate
sulfate
problem,
or
reducing
SO2
in
the
presence
of
substantial
NOx
and
ammonia
could
in
some
cases
exacerbate
the
particulate
nitrate
problem.

For
areas
that
are
nonattainment
for
both
ozone
and
particulate
matter
(
PM
10
and/
or
PM
2.5),
a
modeling
analysis
is
needed
that
addresses
each
pollutant
for
which
the
area
is
nonattainment.
The
net
air
quality
benefit
should
be
based
on
a
comparison
of
the
geographic
area
where
concentrations
change
with
and
without
NO
x
reductions
from
the
sources
concerned.
Alternatively,
the
change
in
population
exposure
to
concentrations
may
be
used.
If
the
modeling
shows
net
disbenefits
for
both
ozone
and
particulate
matter
(
PM
10
and/
or
PM
2.5
for
both
the
short
and
long
term
standards),
EPA
could
approve
the
NOx
exemption
request.
If
the
modeling
shows
a
disbenefit
for
one
pollutant
but
a
benefit
for
the
other,
EPA
would
not
make
a
finding
of
a
net
air
quality
benefit
because
(
1)
there
is
not
a
clear
net
air
quality
benefit
since
it
is
difficult
to
compare
ozone
to
PM
benefits;
(
2)
the
CAA
requires
the
NAAQS
to
be
attained
as
expeditiously
as
practicable
and
granting
the
exemption
could
result
in
delayed
attainment
for
one
pollutant;
and
(
3)
there
are
secondary
benefits
from
NOx
emissions
reductions
such
as
decreased
acid
rain.

D.
Areas
Nonattainment
for
Ozone
and
Carbon
Monoxide,
Lead
or
Sulfur
Dioxide
For
carbon
monoxide,
lead,
and
sulfur
dioxide,
EPA
is
not
aware
of
any
significant
impacts
from
NO
x
emissions.
Therefore,
the
net
air
quality
benefits
determination
should
be
primarily
based
on
the
ozone
modeling
analysis
described
above
for
areas
nonattainment
for
only
ozone.

E.
Secondary
Factors
As
noted
above,
equal
consideration
of
all
NO
x
impacts
is
generally
impractical
in
this
net
air
quality
benefit
test
Draft
6­
30­
04;
Do
not
quote
or
cite
18
because
of
the
lack
of
scales
to
compare
the
impacts
among
the
various
factors.
Nevertheless,
additional
factors
explicitly
addressed
in
the
CAA
such
as
those
listed
below
may
be
considered
in
addition
to
any
information
developed
from
the
NAAQS
analyses.
Consideration
of
the
factors
below
is
especially
important
in
cases
where
the
analyses
on
the
NAAQS
pollutants
cannot
clearly
determine
the
net
air
quality
benefit.
In
any
case,
EPA
believes
the
amended
CAA
places
a
substantial
burden
on
the
applicant
to
provide
a
clear
showing
that
NO
x
reductions
would
be
counterproductive
overall,
considering
the
net
air
quality
benefits.
Additional
factors
to
determine
net
air
quality
benefit
may
include
but
are
not
limited
to:

1.
Effects
associated
with
long­
term
exposures
to
plants,
animals,
and
materials.

2.
Visibility
impairment,
long­
term
and
episodic
acid
deposition,
air
toxics,
and
deposition
of
nitrogen
in
nutrient­
sensitive
watersheds.

3.3
Geographic
Scope
In
contrast
to
the
other
section
182(
f)
tests,
the
net
air
quality
benefit
test
is
not
specifically
limited
to
an
ozone
nonattainment
area
or
ozone
transport
region
and
may
be
directed
at
a
specific
set
of
sources.
Thus,
a
very
broad
geographic
area
should
be
considered.
The
area
may,
in
some
cases,
extend
beyond
an
ozone
nonattainment
area
or
ozone
transport
region.
In
addition,
the
area
must
not
be
so
small
that
downwind
impacts
from
NO
x
emissions
are
not
fully
considered.
Sufficient
area
is
needed
to
allow
for
completion
and
consideration
of
the
various
chemical
transformations
of
NO
x
and
interaction
with
other
pollutants.
At
a
minimum,
the
geographic
area
should
include
the
ozone
nonattainment
area(
s)
encompassing
or
nearby
the
sources
concerned.
For
example,
petitioning
sources
located
in
attainment
portions
of
the
ozone
transport
region
should
analyze
their
impact
on
nearby
nonattainment
areas
and
should
consider
other
factors,
such
as
visibility
impacts
throughout
the
surrounding
area.

3.4
Scenarios
Section
182(
f)
states,
for
this
test,
that
EPA
must
determine
that
the
net
air
quality
benefits
are
greater
in
"
the
absence
of
reductions
of
oxides
of
nitrogen
from
the
sources
concerned."
The
procedure
for
this
test
is
to
first
project
areawide
baseline
emissions
that
may
be
expected
at
the
ozone
attainment
deadline
(
see
sections
3.3
and
8.3).
(
As
described
in
section
8.3,
multi­
year
analyses
may
also
be
conducted.)
Second,
the
projected
baseline
emissions
are
held
constant,
except
for
the
subject
individual
sources.
Then,
the
air
quality
analyses
Draft
6­
30­
04;
Do
not
quote
or
cite
19
are
conducted
for
these
two
scenarios:

1.
the
projected
baseline
emissions
without
NO
x
reductions
from
the
sources
concerned
and
2.
the
projected
baseline
emissions
including
NO
x
reductions
at
all
emission
sources
subject
to
the
NO
x
requirements.

With
respect
to
new
major
sources,
the
two
scenarios
should
take
into
account
application
of
the
section
182(
f)
NSR
requirements
as
described
in
section
8.5.

3.5
Sources
For
this
net
air
quality
benefit
test,
the
CAA
refers
to
"
reductions
of
oxides
of
nitrogen
from
the
sources
concerned."
For
purposes
of
this
analysis,
"
the
sources
concerned"
are
defined
as
the
sources
that
would
be
exempted
from
NO
x
requirements
by
the
petition
or
State
request.
The
sources
concerned
may
be
identified
in
any
of
the
following
ways:
(
1)
specific
individual
sources,
(
2)
one
or
more
source
categories,
or
(
3)
a
geographic
area
containing
a
group
of
sources.
As
described
in
section
3.4,
the
sources
concerned
must
be
analyzed
together
with
other
sources
in
the
area;
these
other
NO
x
sources
should
take
into
account
application
of
any
NO
x
requirements
(
as
part
of
the
areawide
baseline
conditions
expected
at
the
attainment
deadline
year)
which
are
not
the
subject
of
the
exemption
request.
Draft
6­
30­
04;
Do
not
quote
or
cite
20
CHAPTER
4
CONTRIBUTE
TO
ATTAINMENT
4.1
Demonstration
This
demonstration
applies
only
to
ozone
nonattainment
areas
that
are
not
within
an
ozone
transport
region.
The
demonstration
must
show
that
additional
NO
x
reductions
would
not
contribute
to
ozone
attainment
in
the
area.
The
effects
of
substantial
NO
x
reductions
on
ozone
concentrations
should
be
quantified
with
currently
available
air
quality
modeling
techniques
consistent
with
EPA
guidance
(
see
chapter
7).

The
procedure
for
this
test
is
to
utilize
a
photochemical
grid
model
(
see
chapter
7)
to
estimate
future
ozone
design
values
under
conditions
that
may
be
expected
within
the
attainment
deadline
period
considering
three
emission
reduction
scenarios
(
see
chapter
8):
(
1)
substantial
VOC
reductions;
(
2)
substantial
NO
x
reductions;
and
(
3)
both
the
VOC
and
NO
x
reductions.
If
each
predicted
8­
hour
ozone
design
value
concentration
under
scenario
(
1)
is
less
than
or
equal
to
that
from
scenarios
(
2)
and
(
3),
then
the
test
is
passed
and
the
NO
x
requirements
would
not
apply.

In
certain
ozone
nonattainment
areas
it
is
possible
that
NO
x
emission
reductions
may
help
to
reduce
ozone
concentrations
under
some
meteorological
conditions
but
not
under
others.
The
phrase
"
would
not
contribute
to
attainment"
could
be
interpreted
to
mean
that
NO
x
emission
reductions
would
not
help
reduce
(
1)
any
areawide
8­
hour
ozone
concentration,
(
2)
the
majority
of
areawide
8­
hour
ozone
concentrations,
or
(
3)
the
most
severe
areawide
8­
hour
ozone
concentration.
The
EPA
believes
that
the
"
majority"
option
is
not
appropriate
since
this
is
the
only
one
of
the
section
182(
f)
tests
which
is
not
keyed
to
net
benefits.
Furthermore,
(
1)
an
area
may
need
to
demonstrate
attainment
under
multiple
meteorological
conditions,
(
2)
generally
a
small
number
of
episodes
will
be
modeled
and
(
3)
the
NAAQS
is
based
on
multiple
areawide
concentrations
rather
than
a
single
location's,
most
severe
value.
For
the
above
reasons,
EPA
believes
this
determination
should
be
based
on
all
8­
hour
ozone
predicted
design
values.

4.2
Geographic
Scope
This
demonstration
focuses
on
attainment
of
the
ozone
NAAQS
"
in
the
area."
The
EPA
interprets
this
to
mean
in
the
nonattainment
area.
In
contrast
to
the
provision
for
transport
regions,
which
is
likely
to
consider
several
attainment
and
nonattainment
areas
in
the
section
182(
f)
analysis,
this
demonstration
is
limited
to
consideration
of
the
effects
in
a
Draft
6­
30­
04;
Do
not
quote
or
cite
21
single
nonattainment
area
due
to
NOx
emissions
reductions
from
sources
in
the
same
nonattainment
area.

Where
the
demonstration
includes
photochemical
grid
modeling,
EPA
encourages
States/
petitioners
to
include
consideration
of
the
entire
modeling
domain
since
the
effects
of
an
attainment
strategy
may
extend
beyond
the
designated
nonattainment
area.
States
should
consider
such
impacts
since
they
are
ultimately
responsible
for
achieving
attainment
in
all
portions
of
their
State
and
for
ensuring
that
emissions
originating
in
their
State
do
not
contribute
significantly
to
nonattainment
in,
or
interfere
with
maintenance
by,
any
other
State.

However,
EPA
believes
NO
x
exemptions
under
section
182(
f)
of
the
CAA
and
interstate
transport
of
emissions
under
section
110(
a)(
2)(
D)
of
the
Act
must
be
considered
independently.
The
EPA
has
separate
authority
under
section
110(
a)(
2)(
D)
to
require
a
State
to
reduce
emissions
from
stationary
and/
or
mobile
sources
where
there
is
evidence
showing
that
such
emissions
would
contribute
significantly
to
nonattainment
or
interfere
with
maintenance
in
other
States.
In
some
cases,
then,
EPA
may
grant
an
exemption
from
certain
NO
x
requirements
and,
in
a
separate
action,
require
NO
x
emission
decreases
under
section
110(
a)(
2)(
D).

4.3
Applicability
to
Areas
Monitoring
Attainment
In
some
cases,
an
ozone
nonattainment
area
might
attain
the
ozone
standard,
as
demonstrated
by
3
consecutive
years
of
adequate
monitoring
data,
without
having
implemented
the
section
182(
f)
NO
x
provisions
over
that
3­
year
period.
Where
the
NO
x
requirements
were
not
implemented
over
that
3­
year
period,
it
is
clear
that
the
section
182(
f)
language
is
met
since
"
additional
reductions
of
oxides
of
nitrogen
would
not
contribute
to
attainment."
That
is,
since
attainment
has
already
occurred,
additional
NO
x
reductions
could
not
improve
the
area's
attainment
status
and,
therefore,
the
section
NO
x
exemption
could
be
approved.

The
EPA's
approval
of
the
exemption,
if
warranted,
would
be
granted
on
a
contingent
basis
(
i.
e.,
the
exemption
would
last
for
only
as
long
as
the
area's
monitoring
data
continue
to
demonstrate
attainment).
The
State
must
continue
to
operate
an
appropriate
air
quality
monitoring
network,
in
accordance
with
40
CFR
part
58,
to
verify
the
attainment
status
of
the
area.
The
air
quality
data
relied
on
for
the
above
determinations
must
be
consistent
with
40
CFR
part
58
requirements
and
other
relevant
EPA
guidance.
If
it
is
subsequently
determined
by
EPA
that
the
area
has
violated
the
standard,
EPA
would
conduct
notice
and
comment
rulemaking
to
remove
the
NO
x
exemption.
Draft
6­
30­
04;
Do
not
quote
or
cite
22
Draft
6­
30­
04;
Do
not
quote
or
cite
23
CHAPTER
5
NET
OZONE
AIR
QUALITY
BENEFIT
5.1
Demonstration
This
demonstration
applies
in
an
Ozone
Transport
Region.
It
must
show
that
additional
NOx
reductions
would
not
produce
net
ozone
benefits
in
the
transport
region.
In
this
test
the
net
benefit
must
be
demonstrated
on
a
region
wide
basis.
The
EPA
believes
this
test
should
includes
all
portions
of
an
Ozone
Transport
Region
in
which
impacts
from
NO
x
emissions
from
the
area
seeking
the
exemption
can
be
determined
by
the
photochemical
grid
model.

The
procedure
for
this
test
is
to
utilize
a
photochemical
grid
model
(
see
chapter
7)
to
estimate
future
ozone
design
values
under
conditions
that
may
be
expected
within
the
attainment
deadline
period
considering
three
emission
reduction
scenarios
(
see
chapter
8):
(
1)
substantial
VOC
reductions;
(
2)
substantial
NO
x
reductions;
and
(
3)
both
the
VOC
and
NO
x
reductions.
The
net
ozone
benefit
may
be
determined
by
comparing
the
ozone
concentrations
modeled
in
scenario
(
1)
with
results
modeled
from
scenarios
(
2)
and
(
3).
The
net
ozone
benefit
should
be
based
on
a
comparison
of
the
net
geographic
area
where
8­
hour
ozone
concentrations
change
with
and
without
NOx
reductions
from
the
sources
concerned.
Alternatively,
the
net
change
in
population
exposure
to
ozone
concentrations
may
be
used.
If
the
modeling
shows
a
net
disbenefit
for
ozone,
EPA
could
approve
the
NOx
exemption
request.
As
described
in
chapter
8,
multi­
year
analyses
may
also
be
conducted.

5.2
Factors
The
ozone
NAAQS
is
set
at
0.08
parts
per
million
(
ppm).
In
defining
"
net
ozone
benefit,"
however,
EPA
recognizes
that
various
forms
of
expression
could
be
considered
with
respect
to
ozone
impacts.
However,
ozone
concentrations
with
different
averaging
periods
and
values
cannot
readily
be
compared
to
each
other.
For
example,
it
is
difficult
to
compare
a
set
of
1­
hour
ozone
peak
concentrations
above
0.12
ppm
against
a
set
of
8­
hour
ozone
peak
concentrations
above
0.08
and
determine
which
results
are
more
beneficial.

The
EPA
believes
it
is
reasonable
to
focus
the
net
ozone
benefits
test
on
the
8­
hour
0.08
ppm
ozone
NAAQS,
where
possible
for
the
following
reasons:
(
1)
the
0.08
ppm
ozone
NAAQS
has
been
set
by
the
Administrator
as
the
level
necessary
to
protect
the
most
sensitive
individuals
from
adverse
health
effects
with
an
"
adequate
margin
of
safety;"
(
2)
ozone
concentrations
with
Draft
6­
30­
04;
Do
not
quote
or
cite
24
different
averaging
periods
and
values
cannot
readily
be
compared
to
each
other,
and
(
3)
the
purpose
of
the
NO
x
requirements
is
primarily
to
attain
the
ozone
NAAQS.
Therefore,
the
averaging
time
to
be
used
should
be
the
8­
hour
daily
maximum
ozone
concentration
and
the
analysis
should
focus
on
values
above
the
0.08
ppm
NAAQS
level.
Specifically,
the
net
ozone
benefits
test
should
focus
on
the
total
geographic
area
or
total
population
exposed
to
ozone
concentrations
above
the
0.08
ppm
NAAQS
level.

The
model
results
in
some
cases
might
show
all
scenarios
to
be
below
the
0.08
ppm
ozone
NAAQS
level.
In
such
cases
some
might
argue
that
there
is
no
ozone
benefit
and,
thus,
the
NO
x
requirements
should
not
apply.
The
EPA
does
not
agree
with
such
an
interpretation
because
the
CAA
specifies
"
net
ozone"
rather
than
"
ozone
attainment"
for
this
test.
In
such
cases,
the
analysis
should
examine
values
just
below
the
NAAQS
level
so
that
a
comparison
can
be
made.

5.3
Attainment/
Unclassified
Portions
The
section
182(
f)(
1)(
B)
demonstration
explicitly
refers
to
nonattainment
areas
within
an
ozone
transport
region.
The
CAA
does
not
clearly
state
whether
or
not
portions
of
ozone
transport
regions
that
are
attainment/
unclassified
can
make
the
net
ozone
benefit
demonstration.
The
section
182(
f)(
1)
net
air
quality
benefit
test
is
available
to
any
area;
however,
as
noted
previously
it
is
a
higher
hurdle.
Thus,
while
a
severely
polluted
area
might
be
able
to
demonstrate
that
NOx
reductions
do
not
apply
because
the
"
net
ozone
benefits"
test
is
satisfied,
the
CAA
could
be
interpreted
to
require
NOx
reductions
in
the
surrounding
attainment
area
because
that
area
cannot
meet
the
same
test.
It
is
unlikely
that
Congress
intended
such
a
result.

An
alternative
reading
of
the
CAA
can
be
found
through
section
184(
b)(
2).
This
provision
states
that
the
attainment/
unclassified
portions
of
the
transport
region
must
meet
"
the
requirements
which
would
be
applicable
to
major
stationary
sources
if
the
area
were
classified
as
a
moderate
nonattainment
area."
Thus,
the
CAA
could
be
interpreted
to
provide
the
same
section
182(
f)(
1)(
B)
demonstration
process
for
these
attainment/
unclassified
areas,
since
they
should
be
treated
as
moderate
nonattainment
areas
for
the
purpose
of
applying
the
section
182(
f)
requirements
and
moderate
nonattainment
areas
in
the
transport
region
are
eligible
to
meet
the
"
net
ozone
benefits"
test.

Even
without
that
language,
EPA
would
be
inclined
to
allow
an
attainment/
unclassified
area
in
a
transport
region
to
satisfy
the
"
net
ozone
benefits"
test.
It
would
be
absurd
and,
therefore,
it
is
unlikely
that
Congress
intended
to
apply
more
stringent
requirements
in
the
attainment/
unclassified
portions
of
Draft
6­
30­
04;
Do
not
quote
or
cite
25
the
transport
region
than
would
apply
to
the
more
severely
polluted
portions.
Congress
apparently
did
not
intend
any
lesser
requirements
to
apply
in
the
attainment/
unclassified
portions
of
the
transport
region.
The
EPA
believes
that
it
is
appropriate
to
extend
the
section
182(
f)
provision
beyond
the
boundaries
of
a
nonattainment
area
into
adjacent
attainment/
unclassified
areas
which
are
part
of
the
same
section
182(
f)
demonstration.
Thus,
where
a
State/
petitioner
demonstrates
that
NO
x
reductions
would
not
produce
net
ozone
benefits
in
the
transport
region,
then
the
section
182(
f)
NO
x
requirements
would
not
apply
to
those
sources
or
areas
as
described
in
EPA's
approval
action.
Such
a
demonstration
must
include
all
portions
of
the
ozone
transport
region
in
which
impacts
from
NO
x
emissions
from
the
area
seeking
the
exemption
can
be
determined
by
the
photochemical
grid
model.
Draft
6­
30­
04;
Do
not
quote
or
cite
26
CHAPTER
6
EXCESS
EMISSIONS
REDUCTIONS
6.1
General
Section
182(
f)(
2)
provides
the
flexibility
to
limit
the
scope
of
the
NO
x
requirements.
Application
of
the
NO
x
requirements
can
be
limited
to
the
extent
that
any
portion
of
those
reductions
are
demonstrated
to
result
in
"
excess
reductions."
The
tests
for
demonstrating
excess
reductions
are
generally
the
same
as
in
section
182(
f)(
1):
net
air
quality
benefit,
contribute
to
attainment
and
net
ozone
benefit.
However,
in
this
case,
the
demonstration
must
show
that
a
portion
of
the
otherwise
required
NO
x
reductions
are
either
counterproductive
to
the
net
air
quality,
do
not
contribute
to
attainment,
or
do
not
provide
a
net
ozone
benefit
[
depending
on
the
section
182(
f)
test
applied].

As
described
below,
for
the
contribute
to
attainment
or
net
ozone
tests,
the
excess
reductions
test
must
show
that
certain
NO
x
reductions
are
in
excess
of
the
reductions
specified
in
either
the
8­
hour
ozone
attainment
demonstration
contained
in
the
approved
SIP
or
the
8­
hour
ozone
attainment
demonstration
adopted
by
the
State
submitted
to
EPA
for
approval.
The
excess
emission
reductions
may
be
described,
for
example,
as
(
1)
an
areawide
across­
the­
board
tonnage
reduction;
(
2)
emissions
attributed
to
specific
sources;
or
(
3)
emissions
from
a
geographic
portion
of
the
nonattainment
or
transport
area.

6.2
Demonstration
The
"
contribute
to
attainment"
and
"
net
ozone
benefit"
tests
described
in
chapters
4
and
5
require
an
areawide
or
regional
analysis.
In
such
areawide/
regional
analyses,
NO
x
emission
reductions
at
a
large
number
of
sources
are
considered.
These
analyses
are
appropriate
to
determine
in
a
directional
manner
whether
or
not
NO
x
reductions
are
expected
to
be
beneficial
with
respect
to
the
air
quality
in
the
area/
region.
The
analyses
described
in
chapters
4
and
5
may
be
less
precise
than
an
attainment
demonstration
required
under
section
182(
c).

The
EPA
believes
that
the
excess
reductions
provision
requires
a
more
precise
analysis;
specifically
an
analysis
which
is
based
on
the
attainment
demonstration.
That
is,
the
excess
reductions
provision
must
be
more
than
a
directional
finding
on
an
areawide
basis.
Under
the
excess
reductions
provision,
an
analysis
is
needed
to
show
that
a
specific
portion
of
the
total
areawide
NO
x
emissions
is
not
beneficial
under
one
of
the
three
tests.
Thus,
individual
or
groups
of
sources
may
petition
to
show
that,
while
NO
x
reductions
may
be
beneficial
directionally
Draft
6­
30­
04;
Do
not
quote
or
cite
27
in
the
area,
NO
x
reductions
from
their
specific
sources
are
not
beneficial
and,
thus,
should
be
exempt
from
the
NO
x
requirements.

Without
providing
some
constraints
in
this
guidance
document,
the
excess
reductions
provisions
could
undermine
the
section
182(
f)
requirements,
since
each
individual
emission
source
could
theoretically
petition
for
an
exemption
with
the
argument
that
their
small
contribution
to
the
overall
ozone
problem
is
inconsequential.
Such
a
petition
might
be
considered
consistent
with
the
analyses
required
in
chapters
4
and
5,
since
an
exemption
may
be
granted
where
the
modeled
NO
x
reductions
show
no
impact
on
ozone
concentrations.
Certainly,
if
EPA
allowed
very
small
amounts
of
NO
x
reductions
to
be
modeled
individually,
this
interpretation
could
create
a
false
impression
that
individually
the
sources
do
not
affect
attainment
when,
in
fact,
the
aggregate
of
the
sources
does.
Congress
would
not
have
intended,
and
therefore
EPA
does
not
accept
the
argument,
that
the
owner/
operator
of
one
car
or
one
small
boiler
can
be
excused
from
the
CAA
requirements
because
their
emissions,
viewed
alone,
are
small.
Considered
together
with
other
small
contributions,
the
emissions
may
be
important
to
attainment.
That
is,
emissions
from
one
car
or
one
commercial
boiler
would
not
change
the
areawide
ozone
concentration,
yet
together
with
other
cars
or
boilers,
they
may
be
critical
to
the
area's
attainment
strategy.
Furthermore,
as
described
elsewhere
in
this
document,
ozone
air
quality
models
should
not
be
applied
solely
to
determine
the
incremental
effect
of
small
sources
as
such
emissions
could
be
lost
in
the
noise
of
the
air
quality
model
and
emissions
inventory
uncertainties
when
considered
alone.

For
the
above
reasons,
EPA
has
determined
that
the
excess
reductions
demonstration
for
the
"
contribute
to
attainment"
or
"
net
ozone
benefits"
tests
must
be
tied
to
the
area's
SIP
attainment
demonstration.
Thus,
this
test
must
show
that
the
excess
reductions
are
reductions
in
excess
of
those
specified
in
the
area's
attainment
demonstration
and
either
contained
in
the
approved
SIP
or
as
adopted
by
the
State
and
submitted
to
EPA
for
approval.
This
tie
to
the
attainment
demonstration
assures
that
an
excess
reductions
petition
would
not
arbitrarily
be
based
on
small
emissions
and
would
not
undermine
the
State's
control
strategy.

In
contrast,
the
"
net
air
quality
benefit"
test
discussed
in
chapter
3
is
intended
to
address
an
individual
or
small
number
of
sources
and
already
has
an
adequate
constraint.
The
net
air
quality
benefit
test
requires
a
showing
that
NO
x
reductions
specifically
from
the
sources
concerned
are
counterproductive.
The
net
air
quality
benefit
test
imposes
a
higher
hurdle
than
the
other
two
tests
and
EPA
believes
this
higher
hurdle
is
adequate
for
purposes
of
the
excess
emissions
test
as
well.
Draft
6­
30­
04;
Do
not
quote
or
cite
28
CHAPTER
7
MODELING
TECHNIQUES
7.1
Photochemical
Grid
Modeling
As
described
in
chapters
3­
6,
photochemical
grid
modeling
is
generally
needed
to
document
cases
where
NO
x
reductions
are
counterproductive
to
net
air
quality
(
chapter
3),
do
not
contribute
to
attainment
(
chapter
4),
do
not
show
a
net
ozone
benefit
(
chapter
5),
or
include
excess
reductions
(
chapter
6).
The
EPA's
current
modeling
guideline
is
contained
in
40
CFR
part
51,
appendix
W.
In
addition,
procedures
for
modeling
ozone
and
particulate
matter
are
contained
in
EPA
guidance
posted
on
EPA's
web
site
(
http://
www.
epa.
gov/
ttn/
scram/).
The
EPA
has
draft
modeling
guidance
for
use
in
attainment
demonstrations
for
the
ozone
and
PM2.5
NAAQS.

It
is
important
to
note
that
EPA
believes
that
photochemical
grid
models
are
not
sufficient
to
assess
incremental
changes
to
areawide
ozone
concentrations
from
emissions
reductions
at
a
single
or
group
of
small
sources.
Emission
changes
should
amount
to
some
significant
fraction
of
base
emissions
before
modeling
results
can
be
interpreted
with
sufficient
confidence
that
the
results
are
not
lost
in
the
noise
of
the
model
and
the
input
data.
The
EPA
has
reservations
with
respect
to
modeling
NOx
reductions
at
a
single
source
or
group
of
sources
unless
the
modeling
includes
at
least
10%
of
the
domain­
wide
emissions.
Thus,
this
exemption
analysis
is
appropriate
for
groups
of
large
emitters
or
for
consideration
of
entire
source
categories,
rather
than
emission
reductions
at
a
single
or
group
of
small
sources.
However,
EPA
will
consider
on
a
case­
by­
case
basis
an
analysis
that
considers
less
than
a
10%
change
in
the
domain­
wide
emissions.
In
such
cases,
the
analysis
of
a
small
portion
of
the
emissions
would
show
only
a
small
difference
in
ozone
concentration,
if
any,
between
the
with
NOx
and
without
NOx
scenarios,
and,
therefore,
consideration
of
secondary
factors
(
described
below)
is
particularly
important
in
order
to
show
a
net
air
quality
benefit.

The
EPA
investigated
the
feasibility
and
acceptability
of
applying
relatively
inexpensive
screening
techniques
to
evaluate
if
NO
x
control
measures
are
likely
to
be
beneficial
with
respect
to
attainment
of
the
ozone
NAAQS
(
Langstaff
and
Scheffe,
1991).
However,
EPA
determined
that,
as
a
technical
matter,
photochemical
grid
modeling
is
the
only
reliable
tool
to
justify
an
areawide
exemption
from
the
NO
x
requirements.
The
EPA's
reliance
on
photochemical
grid
models
is
supported
by
the
findings
of
the
NAS
on
tropospheric
ozone
(
December
1991).
The
Draft
6­
30­
04;
Do
not
quote
or
cite
29
NAS
report
concluded
that
three­
dimensional
or
grid­
based
ozone
air
quality
models
are
the
best
available
models
for
representing
the
chemical
and
physical
processes
of
ozone
formation.
Less
sophisticated
models,
such
as
EKMA,
lack
the
detailed
treatment/
consideration
of
physical
orientation
of
NO
x
sources
and
dispersion
of
their
plumes.
Further,
since
trajectory
models
only
address
a
limited
number
of
trajectories,
they
cannot
assess
whether
NO
x
control
contributes
to
attainment
at
all
locations
in
an
ozone
nonattainment
area.
Therefore,
such
models
are
insufficient
and
not
acceptable
for
a
NO
x
exemption
demonstration.

7.2
Regional
Modeling
In
an
ozone
transport
region,
the
net
ozone
benefits
test
should
be
met
by
use
of
regional
modeling.
Regional
modeling
is
needed
since
the
section
182(
f)
language
explicitly
refers
to
net
ozone
benefits
"
in
such
region."
For
purposes
of
this
document,
region
wide
or
regional
modeling
includes
all
portions
of
the
ozone
transport
region
in
which
impacts
from
NO
x
emissions
from
the
area
seeking
the
exemption
can
be
determined
by
the
photochemical
grid
model.
Draft
6­
30­
04;
Do
not
quote
or
cite
30
CHAPTER
8
EMISSIONS
ANALYSIS
8.1
General
As
described
in
chapters
3­
6,
photochemical
grid
modeling
is
needed
to
document
cases
where
NO
x
reductions
are
counterproductive
to
net
air
quality
(
chapter
3),
do
not
contribute
to
attainment
(
chapter
4),
do
not
show
a
net
ozone
benefit
(
chapter
5),
or
include
excess
reductions
(
chapter
6).
Application
of
these
models
requires
the
use
of
a
representative
emissions
inventory.
The
EPA's
modeling
guidance
(
chapter
7)
includes
discussion
on
how
to
develop
appropriate
emissions
estimates
for
use
in
the
selected
air
quality
model.
Topics
include
use
of
available
inventory
estimates,
quality
assurance,
application
of
emissions
models
and
estimating
future
emissions.
This
chapter
describes
additional
emission
inventory
requirements
for
the
various
NOx
exemption
demonstrations.

8.2
Years
to
Analyze
In
general,
the
purpose
of
the
NO
x
requirements
is
related
to
attainment
of
the
ozone
standard.
This
suggests
that
a
NO
x
exemption
demonstration
should
focus
within
the
period
ozone
attainment
is
required
(
i.
e.,
the
three
year
period
used
to
determine
attainment).
Further,
many
areas
are
likely
to
develop
modeling
analyses
which
demonstrate
attainment
within
the
attainment
deadline
period.
In
many
cases,
the
emissions
inventory,
meteorological
data,
episode
day
selections,
and
control
strategies
which
support
the
attainment
demonstration
could
also
be
used
to
support
a
NO
x
exemption
analysis.
As
described
in
section
8.4,
the
NO
x
exemption
demonstration
should
be
consistent
with
assumptions
contained
in
the
SIP.
Considering
these
points,
EPA
believes
that
the
NO
x
exemption
demonstrations
should,
at
a
minimum,
reflect
conditions
expected
within
the
three­
year
period
during
which
the
subject
area
is
required
to
attain
the
ozone
standard.

Thus,
base
year
emissions
would
be
projected
to
the
period
reflecting
the
attainment
deadline
and
would
include
growth
in
VOC
and
NO
x
emissions
as
well
as
CAA­
mandated
emission
reductions.
Specific
emission
scenarios
with
and
without
NO
x
reductions
would
be
built
upon
this
projected
emissions
baseline
as
described
elsewhere
in
this
document.
In
addition,
as
described
later
in
this
chapter,
multi­
year
analyses
may
also
be
conducted.

In
an
ozone
transport
region,
a
NO
x
exemption
demonstration
would
likely
cover
an
area
which
includes
ozone
nonattainment
Draft
6­
30­
04;
Do
not
quote
or
cite
31
areas
of
more
than
one
classification,
and
thus
more
than
one
attainment
deadline.
For
example,
a
metropolitan
area
may
have
a
higher
classification
than
a
nearby
rural
nonattainment
area.
For
these
areas,
it
is
possible
that
NO
x
reductions
may
be
beneficial
to
attainment
in
the
near
term
with
respect
to
the
rural
nonattainment
area
(
and
lesser
classification
deadline)
but,
at
the
same
time
or
in
a
longer
timeframe,
NO
x
reductions
might
be
shown
to
be
not
beneficial
when
considering
the
area
as
a
whole
(
since
NO
x
reductions
are
generally
expected
to
be
more
beneficial
in
rural
areas).
In
order
to
determine
whether
the
NO
x
reduction
requirements
should
apply,
EPA
believes
that,
at
a
minimum,
the
NO
x
exemption
demonstration
should
reflect
conditions
expected
at
the
latest
attainment
deadline
period
for
the
area
as
a
whole.

Alternatively,
the
State/
petitioner
may
include
a
multi­
year
analysis
in
its
NO
x
exemption
demonstration.
This
is
appropriate
for
areas
demonstrating
either
a
net
air
quality
benefit
or
a
net
ozone
benefit.
In
these
demonstrations,
the
analysis
may
include
periodic
assessments
of
the
effects
of
NO
x
reductions
and
integrate
those
effects
to
arrive
at
a
finding
on
whether
or
not
NO
x
reductions
are
beneficial.
For
example,
an
area
may
develop
geographic
area
exposure
analyses
for
each
year
or
for
every
third
year
up
to
the
attainment
year
and
assess
the
overall
impact
of
NO
x
reductions
from
that
information.

8.3
Scenarios
to
Compare
For
the
contribute
to
attainment
and
net
ozone
benefit
tests,
the
projected
emissions
should,
at
a
minimum,
consider
three
scenarios
which
vary
emission
reductions
from
anthropogenic
sources:
(
1)
substantial
VOC
reductions;
(
2)
similar
NO
x
reductions;
and
(
3)
both
the
VOC
and
NO
x
reductions.
Total
emissions
to
model
include
both
anthropogenic
and
biogenic
emissions.

In
contrast
to
the
net
air
quality
demonstration
(
chapter
3)
which
focuses
on
the
scenario
"
in
the
absence
of
reductions
of
oxides
of
nitrogen
from
the
sources
concerned,"
the
contribute
to
attainment
and
net
ozone
benefit
demonstrations
concern
an
unspecified
"
additional
reductions"
of
NO
x.
Thus,
while
the
net
air
quality
benefit
test
must
focus
on
NO
x
reductions
specific
to
the
exemption
request,
the
other
demonstrations
may
more
broadly
consider
NO
x
reductions,
including
reductions
that
employ
advanced
control
technology
(
i.
e.,
beyond
RACT).
The
application
of
the
VOC
and
NO
x
reductions
should
be
as
source
category
specific
as
possible,
rather
than
across­
the­
board,
in
order
for
the
results
to
be
most
useful.

In
the
first
scenario
the
demonstration
should
use
the
VOC
reductions
needed
to
attain,
if
available.
Alternatively,
if
the
Draft
6­
30­
04;
Do
not
quote
or
cite
32
attainment
demonstration
has
not
been
completed,
the
demonstration
may
use
some
other
substantial
VOC
reduction.
Reductions
associated
with
attainment
are
appropriate
for
the
reasons
described
above.
In
any
case,
the
VOC
reductions
should
be
substantial
and
documented
as
reasonable
to
expect
for
the
area
due
to
the
CAA
requirements.
For
example,
a
40%
anthropogenic
VOC
reduction
areawide
from
the
2002
emission
inventory
may
be
reasonable
to
expect
for
serious
areas,
considering
motor
vehicle
emission
controls,
inspection/
maintenance,
reasonable
further
progress
and
other
CAA
requirements.

In
the
second
scenario,
NO
x
reductions
should
be
modeled
without
any
VOC
reductions
above
the
attainment
year
baseline.
The
level
of
NO
x
reductions
should
reflect
the
same
percent
reduction
of
anthropogenic
VOC
emissions
in
scenario
(
1)
above.
It
is
important
to
model
this
case
since
NO
x
reductions,
instead
of
additional
VOC
reductions,
may
show
a
clearer
benefit.

In
the
third
scenario,
a
similar
level
of
NO
x
reductions
would
be
modeled
along
with
the
level
of
VOC
reductions
chosen.
That
is,
if
a
40%
VOC
reduction
is
chosen
in
scenario
(
1),
then
the
model
for
scenario
(
3)
would
simulate
a
40%
VOC
reduction
and
approximately
a
40%
NO
x
reduction.
It
would
be
inappropriate
to
select
a
high
level
of
VOC
reductions
and
a
low
level
of
NO
x
reductions
since
this
could
artificially
favor
a
finding
that
NO
x
reductions
are
not
beneficial;
the
two
levels
should
be
similar.

8.4
Consistency
with
the
SIP
Any
NO
x
exemption
demonstration
must
include
a
showing
that
the
exemption
request
uses
assumptions
that
are
consistent
with
requirements
of
the
SIP
and
the
CAA.
It
is
possible
that
a
petition
could
demonstrate
that,
under
some
circumstances,
NO
x
reductions
are
not
needed
to
attain
the
ozone
standard.
However,
unless
the
State
actually
adopts
those
particular
circumstances
into
its
SIP,
there
is
no
assurance
that
the
petition's
analysis
is
valid.
That
is,
if
the
assumptions
contained
in
the
petitioner's
demonstration
are
not
valid,
the
conclusions
are
similarly
not
valid
and
EPA
would
not
approve
the
petition.
The
NO
x
exemption
petition
process
should
not
undermine
the
State's
implementation
plan.
The
petition
should
reflect
measures
consistent
with
mandatory
CAA
requirements,
federally­
approved
SIP
requirements,
and
recent
SIP
revisions
adopted
by
the
State
and
submitted
to
EPA
for
approval.
The
EPA
encourages
petitioners
to
coordinate
these
analyses
with
the
appropriate
State(
s)
as
they
are
being
developed.

8.5
New
Source
Review
The
section
182(
f)
exemption
provisions
center
on
the
effect
Draft
6­
30­
04;
Do
not
quote
or
cite
33
on
ozone
concentrations
due
to
NO
x
emission
reductions.
With
respect
to
RACT,
which
involves
emissions
reductions
from
existing
sources,
this
is
a
perfect
fit.
In
the
case
of
new
or
modified
sources,
however,
other
factors
should
be
considered.
Even
after
the
application
of
on­
site
controls
appropriate
for
a
major
new
or
modified
source,
the
source
will,
considered
alone,
result
in
major
increases
in
NO
x
emissions.
However,
the
NSR
offset
provisions
would
require
the
new
source
to
obtain
emission
reductions
from
other
sources
so
as
offset
any
emissions
increase
associated
with
the
new
source.

To
take
into
account
the
full
impact
of
the
NSR
program,
the
term
"
NO
x
reductions"
must
be
carefully
interpreted.
When
considering
the
air
quality
impacts
in
chapters
3­
6
of
this
document
"
with
NO
x
reductions"
or
with
"
substantial
NO
x
reductions,"
the
analysis
should
reflect
a
zero
emissions
increase
from
stationary
sources
due
to
the
NSR
offset
requirement;
when
considering
the
"
without"
NO
x
reductions
scenarios,
the
analysis
should
include
NO
x
emission
increases
due
to
new
or
modified
stationary
sources
of
NO
x,
many
of
which
would
be
subject
to
the
best
available
control
technology
requirement
through
the
prevention
of
significant
deterioration
program,
but
not
to
offsets.
