
7­
1
7.
Responses
to
Comments
EPA
Region
7
(
Iowa,
Kansas,
Missouri,
and
Nebraska)
7­
2
Comment:
1013a­
30
Region:
7
State:
MO
Area:
St.
Louis,
MO­
IL
Comment:
St.
Louis
CMSA:

St.
Francois
County,
Lincoln,
Warren,
Washington
Counties
and
Sullivan
City
(
in
Crawford
County)
are
not
included
in
the
recommended
nonattainment
area.
Neighboring
Ste.
Genevieve
County's
NOX
emissions
are
projected
to
be
over
18,000
tons
per
year
due
to
new
industrial
growth.
This
county
should
be
included
in
the
nonattainment
area
as
well.

EPA
Response:
As
a
part
of
the
process
to
determine
what
areas
should
be
designated
as
nonattainment,
EPA
first
uses
the
Federal
Reference
Method
(
FRM)
monitors
to
determine
violations
of
the
NAAQS.
The
FRM
monitors
measure
the
total
mass
of
PM2.5
in
the
ambient
air.
These
monitors
are
used
to
calculate
the
values
that
are
compared
to
the
NAAQS
(
15
µ
g/
m3)
in
deciding
if
the
ambient
air
in
an
area
exceeds
the
NAAQS.

Second,
once
an
area
has
a
monitor
violating
the
NAAQS,
EPA
uses
the
speciated
PM2.5
air
quality
data,
along
with
other
data,
to
help
determine
which
counties
in
the
area
are
contributing
to
the
violation.
In
identifying
counties
that
contribute
to
an
area's
violating
air
quality,
it
is
important
give
more
weight
to
emissions
(
sources)
that
contribute
to
the
excess
PM2.5
in
the
urban
area.
For
example,
a
ton
of
nitrogen
oxide
emitted
within
an
area
contributes
less
to
the
PM2.5
in
that
area
than
a
ton
of
organic
carbon
emissions.
Nitrogen
oxide
takes
time
to
form
into
PM2.5
in
the
atmosphere
and
therefore
is
more
of
a
regional
pollutant.
In
addition,
it
will
be
important
to
understand
which
emissions
are
mostly
contributing
to
an
area's
PM2.5
level
in
determining
what
sources
could
be
effectively
controlled
within
the
area.

To
give
each
county
in
an
urban
area
the
proper
"
weight"
for
their
"
contributing"
emissions,
the
emissions
in
the
county
must
be
adjusted
in
two
steps.
In
step
1,
we
must
determine
the
county's
percentage
of
the
violating
area's
total
emissions.
In
step
2,
we
adjust
this
percentage
by
the
violating
area's
excess
urban
emissions
for
the
pertinent
speciated
PM2.5
component.
In
doing
this,
we
calculate
the
excess
levels
associated
with
sulfates,
nitrates,
carbonaceous
matter
and
crustal
material.
These
components
represent
the
vast
majority
of
chemicals
that
make
up
PM2.5
in
urban
areas.

The
calculated
urban
excess
for
each
of
the
four
components
is
the
difference
between
the
speciated
PM2.5
components
for
an
urban
area
and
speciated
components
from
a
near­
by
rural
area.
While
it
may
seem
best
to
choose
a
"
rural"
FRM
(
total
mass)
monitor
and
an
"
urban"
FRM
monitor
for
purposes
of
estimating
the
mass
of
the
urban
excess,
this
would
not
allow
us
to
relate
the
air
quality
levels
to
the
area's
emissions.
This
situation
is
one
of
the
main
reasons
for
a
monitoring
network
for
speciated
PM2.5.
Accordingly,
we
are
using
the
speciated
PM2.5
data
from
rural
and
urban
monitors,
along
7­
3
with
estimates
of
emissions
within
the
area,
to
identify
the
urban
sources
with
the
greatest
contribution
to
the
urban
excess
PM2.5.

It
is
also
important
to
note
that
the
PM2.5
(
air
quality)
weighted
emissions
(
and
scores)
are
considered
in
the
context
of
all
the
relevant
factors
in
determining
the
boundary
of
a
nonattainment
area.
We
consider
the
other
factors,
in
addition
to
air
quality
and
emissions,
in
identifying
the
counties
that
should
comprise
the
nonattainment
area.
As
described
above,
the
speciated
PM2.5
weighted
emissions
are
used
in
developing
a
ranking
score
(
weight)
for
each
county
in
a
potential
nonattainment
area.
In
developing
these
scores,
we
do
not
intend
that
they
be
used
in
"
bight­
line"
manner.
Rather,
they
offer
a
basis
for
looking
closest
at
the
counties
in
an
area
that
may
contribute
to
the
most
to
the
elevated
PM2.5
in
the
area.
For
the
counties
with
the
highest
score,
we
look
at
the
other
information
as
we
determine
the
collection
of
counties
in
a
nonattainment
area.

As
such,
recognizing
the
process
described
above,
EPA
evaluated
Lincoln,
Warren,
Crawford,
St.
Francois,
Ste.
Genevieve,
Washington,
St.
Louis,
Jefferson,
St.
Charles,
Franklin
counties
and
the
City
of
St.
Louis
in
the
Missouri
portion
of
the
St.
Louis
MSA.

Lincoln,
Warren,
Crawford,
St.
Francois,
Ste.
Genevieve,
and
Washington
counties
were
not
included
in
the
nonattainment
designations
for
a
number
of
reasons:

1.
None
of
these
counties
contain
violating
PM2.5
monitors.

2.
All
of
these
counties
had
relatively
low
contribution
to
the
PM2.5
violations
as
reflected
in
the
weighed
emissions
scores.
In
fact,
the
weighed
emission
score
values
for
Lincoln,
Warren,
Crawford,
St.
Francois,
St.
Genevieve,
and
Washington
counties
fell
below
9.1,
which
was
the
natural
break
in
the
weighted
emission
Scores
for
all
Missouri
MSA
counties
and
counties
adjacent
to
the
St.
Louis,
Missouri
MSA.

3.
None
of
these
counties
were
recommended
for
a
nonattainment
designation
by
the
state
of
Missouri,
which
had
provided
substantial
technical
analysis
in
support
of
their
designation
recommendation.

Specifically,
in
regards
to
Ste.
Genevieve
County,
emissions
were
adjusted
to
account
for
industrial
growth
from
new
permits
and
PSD
applications
received
by
the
state
of
Missouri.

Further
county
specific
information
is
included
in
the
Technical
Support
Document.
