North
Carolina
Recommendation
for
Johnston
County
The
purpose
of
this
paper
is
to
discuss
the
rationale
for
recommending
the
western
portion
of
Johnston
County
(
west
of
Interstate­
95),
rather
than
the
entire
county,
as
nonattainment
for
the
8­
hour
ozone
standard.
The
recommendation
is
for
the
portion
of
Johnston
County
that
covers
both
the
monitor
site,
and
the
advance
of
housing
developments
from
the
Wake
County
(
Raleigh)
urban
area.

 
First,
this
area
has
a
marginal
8­
hour
ozone
problem,
with
a
design
value
in
2000­
2002
of
0.085
ppm,
and
a
design
value
in
2001­
2003
of
0.085
ppm.
 
Second,
based
on
the
2000
census,
121,965
people
live
in
Johnston
County
while
approximately
98,116
people
live
in
the
area
recommended
as
nonattainment.
The
eastern
portion
of
the
County
is
fairly
rural,
with
one
large
census
tract
with
0­
50
people
per
square
mile
and
two
census
tracts
with
50­
100
people
per
square
mile.
The
two
remaining
census
tracts
all
have
100­
250
people
per
square
mile.
The
area
recommended
as
nonattainment
is
adjacent
to
Wake
County
and
the
monitor
is
located
southeast
of
Clayton.
North
Carolina
believes
that
the
urbanized
portion
of
the
county
has
been
captured
in
the
nonattainment
recommendation.
Additionally,
there
is
a
large
area
east
of
I­
95
and
bordered
by
US70
and
Highway
701
that
includes
Quincosin
Swamp
and
Raccoon
Swamp
where
development
is
not
likely
to
ever
occur
due
to
the
presence
of
the
wetlands.
 
Third,
the
majority
of
the
NOx
emissions
in
Johnston
County
are
generated
from
mobile
sources.
Based
on
1997
emissions
inventories,
Johnston
County
has
33.89
tons
per
day
of
NOx
(
state
total
is
2529
tons
per
day)
and
the
county
has
28.27
tons
per
day
of
VOC
(
state
total
is
1842
tons
per
day
 
anthropogenic
only).
The
majority
of
the
total
tons
per
day
of
NOx
emissions
are
from
mobile
sources
(
25.59
tons
per
day).
The
combined
effect
of
Federal
and
State
control
programs
will
address
these
emissions.
The
NC
inspection
and
maintenance
program
began
in
Johnston
County
on
July
1,
2003.
Low
sulfur
gasoline
will
be
required
statewide.
 
Winds
in
Johnston
County
are
climatologically
from
the
southwest
during
the
ozone
season.
With
this
climatological
wind
pattern,
the
county
is
not
in
an
upwind
sector
that
would
routinely
have
an
impact
on
air
quality
in
the
urban
portion
of
the
Raleigh/
Durham/
Chapel
Hill
MSA.
 
On
the
limited
number
of
days
when
the
monitor
exceeds
the
8­
hour
standard,
it
appears
to
be
measuring
the
Raleigh/
Durham/
Chapel
Hill
urban
plume.
The
exceedances
often
coincide
with
a
wind
from
the
northwest.
A
classic
example
is
the
summer
of
2002
that
had
an
abnormally
frequent
northwesterly
wind.
The
West
Johnston
site
exceeded
the
8­
hour
standard
on
19
days
that
year.
During
summers
(
such
as
2000,
2001
and
2003)
when
the
climatological
wind
pattern
dominated
(
southwesterly),
the
West
Johnston
site
averaged
less
than
2
exceedance
days
per
year.
As
the
pollution
in
the
Raleigh/
Durham/
Chapel
Hill
area
is
reduced,
the
monitor
should
observe
lower
ozone
levels.
 
Finally,
North
Carolina
expects
this
area
to
attain
by
2007
based
on
the
most
recent
air
quality
modeling
analysis.
The
future
(
2007)
design
value
­
which
is
based
on
an
application
of
the
US
EPA's
modeled
attainment
test
­
at
the
monitor
in
Johnston
County
(
West
Johnston)
is
projected
to
be
0.075
ppm.
 
Based
on
the
information
presented
above,
North
Carolina
continues
to
believe
this
is
an
appropriate
boundary
for
this
region.
This
site
is
clearly
a
"
downwind"
area
from
the
emissions
of
any
consequence
and
the
West
Johnston
monitor
was
sited
at
that
location
to
be
the
downwind
monitor
for
the
upwind
source
area
that
North
Carolina
is
recommending
for
non­
attainment.
