REPORT FOR CONSULTATION ON THE
METROPOLITAN INDIANAPOLIS INTRASTATE
AIR QUALITY CONTROL REGION
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
Public Health Service
Consumer Protection and Environmental Health Service
National Air Pollution Control Administration
-------
REPORT FOR CONSULTAJ.J.GN ON THE
METROPOLITAN INDIANAPOLIS
INTRASTATE AIR QUALITY CONTROL REGION
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
U.S. PUBLIC HEALTH SERVICE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
MAY 1969
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CONTENTS
PREFACE
INTRODUCTION
EVALUATION OF ENGINEERING FACTORS
EMISSION INVENTORY 9
AIR QUALITY ANALYSIS 16
EVALUATION OF URBAN FACTORS 28
THE PROPOSED REGION 44
DISCUSSION OF PROPOSAL 47
REFERENCES 50
APPENDIX A 51
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PREFACE
The Secretary, Department of Health, Education, and Welfare is
directed by the Air Quality Act of 1967 to designate "air quality
control regions" as an initial step toward the establishment of
regional air quality standards. In addition to listing the major
factors to be considered in the designation of region boundaries,
the Act stipulates that the designation of a region shall be pre-
ceded by a consultation with appropriate State and local authorities.
The National Air Pollution Control Administration, DREW, has
conducted a study of the Metropolitan Indianapolis urban area, the
results of which are presented in this report. The boundaries of
the Region*, as proposed in this report, reflect consideration of
all available and pertinent data; however, the boundaries remain
subject to revision suggested by consultation with State and local
authorities. Formal designation, will be withheld pending the out-
come of that consultation.
The Administration is appreciative of assistance received "either
directly during the course of this study or during previous activities
in the Metropolitan Indianapolis area from the Indiana Air Pollution
Control Board and the Indianapolis Bureau of Air Pollution Control.
*For the purposes of this report, the word region, when capitalized,
will refer to the Metropolitan Indianapolis Intrastate Air Quality
Control Region. When not capitalized, unless otherwise noted, it
will refer to air quality control regions in general.
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Useful data was also supplied by the Indiana Department of Commerce,
the Indiana Employment Security Division, the Metropolitan Planning
i
Department of Marion County, the Hendricks, Shelby, Boone, Johnson,
Hancock and Morgan County Plan Commissions, the Delaware-Muncie
Metropolitan Planning Commission, the Anderson City Plan Commission,
and the Carmel City Plan Commission.
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INTRODUCTION
"For the purpose of establishing ambient
air quality standards pursuant to section 108,
and for administrative and other purposes, the
Secretary, after consultation with appropriate
State and local authorities shall, to the extent
feasible, within 18 months after the date of
enactment of the Air Quality Act of 1967 designate
air quality control regions based on jurisdictional
boundaries, urban-industrial concentrations, and
other factors including atmospheric areas necessary
to provide adequate implementation of air quality
standards. The Secretary may from time to time
thereafter, as he determines necessary to protect
the public health and welfare and after consultation
with appropriate State and local authorities, revise
the designation of such regions and designate
additional air quality control regions. The Secretary
shall immediately notify the Governor or Governors
of the affected State or States of such designation."
Section 107(a)(2), Air Quality Act of 1967
THE AIR QUALITY ACT
Air Pollution in most of the Nation's urban areas is a regional
problem. This regional problem demands a regional solution, consisting
of coordinated planning, data gathering, standard setting and
enforcement. Yet, with few exceptions, such coordinated efforts are
notably absent among the Nation's urban complexes.
Beginning with the Section quoted above, in which the Secretary
is required to designate air quality control regions, the Air Quality
Act presents an approach to air pollution control involving coordinated
efforts by Federal, State, and local governments, as shown in Figure 1.
After the Secretary has (1) designated regions, (2) published air
quality criteria, and (3) published corresponding documents on control
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HEW DESIGNATES
AIR QUALITY
CONTROL REGIONS.
HEW DEVELOPS AND
PUBLISHES AIR
QUALITY CRITERIA
BASED ON'sCIENTJFic
EVIDENCE OF AIR
POLLUTION EFFECTS.
HEW PREPARES
AND PUBLISHES
REPORTS ON
AVAILABLE CONTROL
TECHNIQUES
STATES INDICATE
THEIR INTENT
TO SET STANDARDS.
(PUBLIC
HEARINGS)
STATES SET
AIR QUALITY
STANDARDS
FOR THE AIR
QUALITY CONTROL
REGIONS.
I
STATES ESTABLISH
COMPREHENSIVE PLANS
FOR IMPLEMENTING
AIR QUALITY
STANDARDS.
STATES SUBMIT
STANDARDS FOR
HEW REVIEW.
1
STATES SUBMIT
IMPLEMENTATION PLANS
FOR HEW REVIEW.
STATES ACT TO CONTROL
AIR POLLUTION IN ACCORDANCE
WITH AIR QUALITY STANDARDS
AND PLANS FOR IMPLEMENTATION.
Figure 1 FLOW DIAGRAM FOR ACTION TO CONTROL AIR POLLUTION ON A REGIONAL
BASIS, UNDER THE AIR QUALITY ACT.
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technology and associated costs, the Governor(s) of the States(s)
must file with the Secretary within 90 days a letter of intent,
indicating that the States(s) will adopt within 180 days ambient air
quality standards for the pollutants covered by the published criteria
and control technology documents and adopt within an additional 180
days plans for the implementation, maintenance, and enforcement of
those standards in the designated air quality control region.
The new Federal legislation provides for a regional attack on air
pollution and, at the same time, allows latitude in the form which
regional efforts may take. While the Secretary retains approval authority,
the States(s) involved in a designated region assumes the responsibility
for developing standards and an implementation plan which includes
administrative procedures for abatement and control. Informal cooperative
arrangements with proper safeguards may be adequate in some regions,
whereas in others, more formal arrangements, such as interstate compacts,
may be selected. The objective in each instance will be to provide
effective mechanisms for control on a regional basis.
THE SIZE OF A REGION '
Several objectives are important in determining how large an air
quality control region should be. Basically, these objectives can be
divided into three separate categories. First a region should be self-
contained with respect to air pollution sources and receptors. In other
words, a region should include most of the important sources in the area
as well as most of the people and property affected by those sources.
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In this way, all the major elements of the regional-problem will lie
within one unified administrative jurisdiction. Unfortunately, since
air pollutants can travel long distances, it is impractical if not
impossible to delineate regions which are completely self-contained.
The air over a region will usually have at least trace amounts of
pollutants from external sources. During episodic conditions, such
contributions from external sources may even reach significant levels.
Conversely, air pollution generated within a region and transported out
of it can affect external receptors to some degree. It would be impractical
and inefficient to make all air quality control regions large enough to
encompass these low-level effects. The geographic extent of trace effects
overestimates the true problem area which should be the focus of air
pollution control efforts. Thus, the first objective, that a region be
self-contained, becomes a question of relative magnitude and frequency.
The dividing line between "important influence" and "trace effect" will
be a matter of judgement. The judgement should be based on estimates of
the impact a source has upon a region, and the level of pollution to
which receptors are subjected. In this respect, annual and seasonal data
on pollutant emissions and ambient air concentrations are a better measure
of relative influence than short term data on episodic conditions.
The second general objective requires that region boundaries be
designed to meet not only present conditions but also future conditions.
In other words, the region should include areas where industrial and
residential expansion are likely to create air pollution problems in
the foreseeable future. This objective requires careful consideration
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of existing metropolitan development plans, expected population growth,
and projected industrial expansion. Such considerations should result
in the designation of regions which will contain the sources and receptors
of regional air pollution for a number of years to come. Of course, region
boundaries need not be permanently fixed, once designated. Boundaries
should be reviewed periodically and altered when changing conditions
warrant readjustment.
The third objective is that region boundaries should be compatible
with and even foster unified and cooperative governmental administration
of the air resource throughout the region. Air pollution is a regional
problem which often extends across several municipal, county, and even
state boundaries. Clearly, the collaboration of several governmental
jurisdictions is prerequisite to the solution of the problem. Therefore,
the region should be delineated in a way which encourages regional
cooperation among the various governmental bodies involved in air
pollution control. In this regard, the existing pattern of governmental
cooperation on the whole range of urban problems may become an important
consideration. Certainly the pattern of cooperation among existing air
I
pollution control programs is a relevant factor. In general, administrative
considerations dictate that governmental jurisdictions should not be
divided. Although it would be impractical to preserve State jurisdictions
undivided, usually it is possible to preserve the unity of county
governments by including or excluding them in their entirety. Occasionally,
even this would be impractical due to a county's large size, wide variation
in level of development, or striking topographical features.
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To the extent that any two of the above three objectives lead to
incompatible conclusions concerning region boundaries, the region must
represent a reasonable compromise. A region should represent the best
way of satisfying the three objectives simultaneously.
PROCEDURE FOR DESIGNATION OF REGIONS
Figure 2 illustrates the procedures used by the National Air
Pollution Control Administration for designating air quality control
regions.
A preliminary delineation of the region is developed by bringing
together two essentially separate studies - the "Evaluation of Engineering
Factors", and the "Evaluation of Urban Factors".
The "Evaluation of Engineering Factors" considers pollutant source
locations and the geographic extent of significant pollutant concen-
trations in the ambient air. An inventory of air pollutant emissions
determines the geographic location and quantities of the various
pollutants emitted from the sources in a region. Major quantities of
pollution are emitted by automobiles and industry, and from refuse
disposal operations, power generation, and space heating. The sub-
sequent effect of the pollution emitted into the atmosphere is deter-
mined by measuring ambient air quality. The air quality analysis
presented in this report is divided into two major parts. The first
part deals with the topography and meteorology of the area and
measured air quality. The second part of the analysis describes the
results of the diffusion model applied to the Indianapolis area in
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ENGINEERING EVALUATION
EMISSIONS INVENTORY
METEOROLOGY
AIR QUALITY ANALYSIS
EXISTING AIR QUALITY DATA
DIFFUSION MODEL OUTPUT
URBAN FACTORS
Jurisdictional Boundaries
Urban-Industrial Concentrations
Cooperative Regional Arrangements
Pattern and Rate of Growth
Existing State and Local Air
Pollution Control Legislation & Programs
Preliminary
Delineation
of
Regions
Consultation
with State
and Local
Officials
Formal
Designation
by
Secretary-HEW
Figure 2. Flow diagram for the designation of air quality control regions.
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order to predict air quality levels. Some of the basic conclusions drawn
from the model results, as they relate to the size of the proposed
Region, are outlined.
The "Evaluation of Urban Factors" encompasses all considerat-
ions of a non-engineering nature. This evaluation consists of a
review of existing governmental jurisdictions, current air pollution
programs and legislation, demographic data, current urbanization,
and projected patterns of urbanization.
The findings of the engineering evaluation are combined with the
results of the urban factors evaluation, and an initial proposal for
the air quality control region is made. As indicated in Figure 2, the
proposal is submitted for consultation with State and Local officials.
The report itself is intended to serve as a background document for the
formal consultation. After reviewing the official transcript of the
consultation proceedings which provides the viewpoints of the State and
local officials toward the proposal, the Secretary formally designates
the region. Formal designation includes a notice in the Federal Register
and a notification to the Governor(s) of the State(s) affected by
the designation.
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EVALUATION OF ENGINEERING FACTORS
EMISSION INVENTORY
A quantitative evaluation of air pollutant emissions provides the
basic framework for air conservation activities. The compilation of an
emissions inventory makes possible the correlation of pollutant emissions
with specific geographic locations. This procedure generally results in
the identification of the "core" of an air quality control region that
is, the area where the bulk of the pollutant emissions occur. In this
study, the emissions inventory results are further utilized as input data
to a meteorological diffusion model. In this manner the spatial and
temporal distribution of the pollution emitted into the atmosphere can
be systematically predicted. For these reasons, a presentation of the
emissions inventory results serves as a logical starting point in the
engineering evaluation.
The emission inventory for the Indianapolis area was conducted by
the Division of Air Quality and Emission Data of the National Air
Pollution Control Administration. Emissions were surveyed over the eight
county Indianapolis Standard Metropolitan Statistical Area (SMSA). The
counties involved are Boone, Hamilton, Hancock, Hendricks, Johnson,
Marion, Morgan and Shelby. This 3,080 square mile area contains 1,043,000
persons (estimated 1967), 72% of whom reside in Marion County.
The Public Health Service rapid survey technique was used, with some
modification, for the estimation of pollutant emissions. The emissions
were calculated from data representative of the year 1967 using Public
ty
Health Service emission factors. Table I provides a breakdown of
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TABLE I. SUMMARY OF AIR POLLUTANT EMISSIONS IN THE METROPOLITAN
INDIANAPOLIS STUDY AREA, 1967. (Tons/Year).
COMBUSTION OF FUEL, STATIONARY
TRANSPORTATION
di
o
g
O
H
°
&
a
in
a
0
o
H
IH
£
i-*
rt
*
0)
a
ri
X
o
0
S
n
o
JQ
K
at
o
COUNTY
Boone
Hamilton
Hancock
Hendricks
Johnson
Marion
Morgan
Shelby
TOTAL
Boone
Hamilton
Hancock
Hendricks
Johnson
Marion
Morgan
Shelby
TOTAL
Boone
Hamilton
Hancock
Hendricfcs
Johnson
Marion
Morgan
Shelby
TOTAL
MOTOR VEHICLES
60
110
60
80
130
1,700
70
70
2,350
100
180
110
140
230
2,960
130
110
3,960
9,000
18 ,500
11,630
15,320
25,200
513,500
12,600
11,500
617,250
AIRCRAFT
Neg.*
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
Neg.
400
Neg.
Neg.
400
Neg.
Neg.
Neg.
Neg.
Neg.
5,260
Neg.
Neg.
5,260
INDUSTRIAL
30
40
10
Neg.
50
32,880
20
60
33,090
10
10
Neg.
Neg.
10
7,700
Neg.
20
7,750
Neg.
Neg.
Neg.
Neg.
Neg.
1,450
Neg.
Neg.
1,450
RESIDENTIAL
340
630
360
500
450
6,750
500
410
9,940
160
220
140
180
160
2,340
200
160
3,560
210
290
180
220
210
2,730
290
220
4,350
COMMERCIAL &
INSTITUTIONAL
30
40
10
20
10
6,200
40
80
6,430
10
20
Neg.
10
Neg.
3,370
20
30
3,460
Neg.
Neg.
Neg.
Neg.
Neg.
3,300
Neg.
Neg.
3,300
SOURCES
STEAM- ELECT.
0
3,480
0
0
0
57,920
46 , 300
0
107,700
0
2,100
0
0
0
24,040
17,960
0
44,100
0
20
0
0
210
220
200
0
650
REFUSE DISPOSAL
0
0
0
0
0
0
0
0
0
145
235
160
245
255
3,760
200
180
5,180
780
1,270
860
1,300
1,380
20,000
1,100
970
27,660
INDUSTRIAL PROCESS
EMISSIONS
Neg.
Neg.
Neg.
Neg.
Neg.
4,500
Neg.
Neg.
4,500
Neg.
Neg.
Neg.
Neg.
Neg.
10,000
Neg.
Neg.
10,000
Neg.
Neg.
Neg.
Neg.
Neg.
97,000
Neg.
Neg.
97,000
*Negligible
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11
sulfur dioxide*, total particulate-and carbon monoxide emissions by
county according to source type in four general categories. These
categories are transportation, fuel combustion in stationary sources,
refuse disposal and industrial process emissions. The data presented
in this table indicates that the major portion of SC>2, CO and total
particulate emissions are attributable to sources located within Marion
County. It is also evident from this table that power plants located
in Hamilton and Morgan Counties emit significant quantities of S02 and
total particulates. Figures for the entire survey area reveal that power
plants are responsible for 667, of the total S02 emissions and 57% of
the total particulate emissions while 82% of CO emissions are attributable
to road vehicles.
The geographic location of sources within the survey area are defined
by the use of grid coordinates based on the Universal Transverse Mercator
(UTM) System. The numbered grid system is shown in Figure 3, super-
imposed over a map of the study area. Grid squares 5 kilometers on a side
are used in the areas of most dense population and industrialization.
Grid squares 10 kilometers and 20 kilometers on a side are used in areas
of less dense urbanization.
Figures 4, 5, and 6 are maps representing yearly average daily
emission densities for S02, CO, and total particulates respectively,
based on the grid system. The densities are computed on the basis of
emissions from both point sources and area sources within each grid
* Estimates are based on all oxides of sulfur, of which the vast majority
is composed of SOo.
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12
431
m £A """~^^^ ~" »^^
BOONE CO.
30
L
I
i,
11 i
HEN
t_-
%
\
[ MOR
I
I _,
1 1
1
I
1
31
1
12
DRICKS CO.
7 I
GAN CO.
.
2
1
HAMIL
38
1
32
MARION
23
19
24
20
13
39
35
33
CO.
25
21
16
14
36
34
26
22
17
15
Q
1
JOHNSt
3 1
1
I
46
TON CO.
40
37
r
27
' I
,
41.
r~
i
1
28
-
1
)N CO.
1
4
1
-- L-
HAN COO
SHI
42
29
CO.
10
:LBY co.
5
"1
r1
1
i
N
kilometers
Figure 3. Indianapolis grid coordinate map.
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13
kilometers
SULFUR OXIDES,
ton/mi 2-doy
n < o.oi
[^ 0.01 - 0.05
(13 0.05 - 0.15
HJ 0.15 - 0.45
§3 0.45 - 0.90
0.90 - 5.0
N
Figure4. Sulfur oxide emission density from all sources in the Indianapolis study area, 1967.
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14
kilometers
I
CARBON MONOXIDE,
ton/mi 2-day
D « °-07 |
[^ 0.07 - 0.20
pT] 0.20 - 0.80
Hjj 0.80 - 3.20
fU 3.20 - 9.60
9.60 - 20.00
Figure 5. Carbon monoxide emission density from all sources in the Indianapolis study area, 1967.
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15
PARTICULATES,
ton/mi 2-Joy
Q < 0.01
[2J0.01 - 0.05
£30.05 - 0.10
^JO.10 - 0.25
^0.25 - 0.50
0.50 - 2.00
N
Figure 6. Particulate emission density from all sources in the Indianapolis study area, 1967.
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16
zone. The areas of greatest pollutant emissions are located within and
immediately surrounding the city of Indianapolis. The majority of the
S02 and total particulate emissions occur within Marion County. Also,
significant quantities of these two pollutants are emitted from Morgan
and Hamilton Counties. The source complexes of other peripheral counties
emit smaller quantities of SC^ and total particulates. Total carbon
monoxide emissions are also greatest in Marion County and are particular-
ly dense within the city of Indianapolis. These emissions are closely
related to the vehicular traffic intensity and geographic distribution.
Lesser CO emissions occur in a somewhat uniform ring around Marion
County. Figure 7 indicates that most major pollutant point sources
(S02, CO and/or total particulate emissions) are located within Marion
County.
AIR QUALITY ANALYSIS
Introduction
To facilitate the administration of an air resource management
program, an air quality control region should include those
jurisdictions containing the majority of air pollutant sources in a
region as well as the majority of people and property adversely
affected by the source emissions. The core area of a region can be
roughly defined on the basis of pollutant point source locations and
relative emission densities. However, a determination of ambient air
quality is necessary in order that the peripheral pollutant receptor
areas may be identified and considered for inclusion in the region.
This procedure results in an essentially self-contained region,
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17
1
--* ' --
BOONE CO.
I
1
J HEN
1
1
S-
f MOF
1
L ,
1
1
1
1
DRICKS CO.
1
CAN co.
'
.
-
i
1
"
i
Mi
HAMILTON CO. 1
i
X
MARION
K X
ft
XX
CO.
X
,
X
1
{ JOHNSf
I
1
1
t
i
r
X
X
i
)N CO.
I
i
J
HANCOO
SH!
1
CO.
i
ILBY CO.
1
f
I
1
1
rJ
N
! 10
kilometers
o Commercial
X Industrial
Power plant
FIGURE 7. MAJOR POINT SOURCE LOCATIONS.
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18
one which includes within its bounds virtually the entire pollutant
source-receptor system for a particular area. In this way too, the
possibility of pollutant transport across boundaries will be
minimized. Two alternate approaches exist for the determination
of air quality in metropolitan Indianapolis.
The first and most logical approach is to measure quantitatively
pollutant concentrations in the ambient air. A review and evaluation
of such measured data will be presented in the following section.
The second approach consists of predicting air quality, in
terms of concentrations of individual pollutants, by the use of a
meteorological diffusion model. This technique is particularly
desirable in the Indianapolis area since existing air-sampling
networks do not encompass large enough areas to be useful as guides
for the establishment of the Region boundaries.
Topography, Meteorology, and Measured Air Quality
Indianapolis is located in the central part of the State of
Indiana and is situated on mostly level or' slightly rolling
terrain. The majority of the City lies east of the White River,
which flows in a generally north-south direction through Marion
County. It is not likely that meteorological conditions which would
create localized air pollution or air pollution of great severity
would be caused directly by topographical influences.
The climate in Indianapolis is continental, with warm summers,
moderately cold winters, and occasional wide variations in temperature,
particularly during the colder seasons. Hot, humid weather caused
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19
by warm air masses occurs occasionally during the summer, though
these air masses are soon replaced by cooler, drier air from the
north. Precipitation is generally evenly distributed throughout
the year. Prevailing winter winds are from the northwest (see
Figure A-l, Appendix A), while prevailing summer and annual winds
are from the southwest. The greatest dilution potential for
pollutants in the atmosphere occurs during summer afternoons,
while pollutant dilution is most restricted during summer mornings.
Air sampling in Indianapolis is conducted by the Indianapolis
Bureau of Air Pollution Control and by the Indiana Air Pollution
Control Board. Public Health Service stations measuring gaseous
pollutants are located in the city of Indianapolis and in Monroe
County (located to the south of Morgan County). The majority of
the sampling has been for particulate pollution. A ten-station 1967
yearly average concentration of suspended particulates in
o
Indianapolis was 116 ug/m . The PHS station located within that
city recorded an average concentration of 132 ug/m3 for the same
time period. The maximum concentration of suspended particulates
o
recorded at one station in Indianapolis in 1967 was 570 ug/m , based
i
on a 24-hour average. During the same year suspended particulate
concentrations exceeding 200 ug/m3 at individual stations (24-hour
average values) were not unusual. Measurements taken in the city
of Anderson in Madison County produced a 1967 yearly average
concentration of 93 ug/m3. In contrast to these values, measurements
at the non-urban sampling site in Monroe County produced a yearly
average concentration of 51 ug/m3. This value can be regarded as a
representative background concentration for the Indianapolis area.
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20
Thus, measurements within the cities of Indianpolis and Anderson
indicate that relatively high suspended particulate concentrations
exist. Diffusion model results (see Figure 8) indicate that
above-background suspended particulate concentrations are not
confined solely to the city of Indianapolis but affect, to some
degree, the remainder of Marion County and portions of Morgan,
Johnson, and Hendricks Counties.
Monitoring of sulfur dioxide concentrations in the ambient
air has been limited. Stations exist in the city of Indianapolis
and at the Monroe County non-urban site. The 1965 average of
biweekly 24-hour average SC>2 concentrations within the city of
Indianapolis was approximately .018 ppm. The comparable value for
1966 was .015 ppm, and was approximately .020 ppm for 1967. These
concentrations are similar to those measurements for other major
cities of approximately the same size as Indianapolis and are, as
expected, lower in value than similar average SQ~ concentrations
for larger cities such as Chicago and Philadelphia.^ The 1966 mean
concentration of S0£ at the Monroe County non-urban site was .004
ppm. This represents a rough measure of the S02 background level
in the Indianapolis area. It is clear that S02 measurements within
the city of Indianapolis are significantly above this level.
No 1967 sampling data are available for carbon monoxide
concentrations in the Indianapolis area. As a result, no validation
of diffusion model results by comparison with measured CO concen-
trations is possible. Previous applications of the diffusion model
to other urban areas considered in consultation reports have shown
that the model generally tends to underestimate measured CO concentrations.
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21
Diffusion Model Results
The meteorological diffusion model has been used to compute
suspended particulate, sulfur dioxide and carbon monoxide concen-
trations in the ambient air at specified receptor points. The
model predicts these concentrations from the mathematical treatment
of pollutant emission and meteorological data.* While the model
contains inherent limitations, it still has merit in providing
reasonable spatial distributions of long term (seasonal and
Me
annual) average pollutant concentrations.
Figure 8 shows theoretical suspended particulate concentrations
O
in ug/nr for the summer averaging time. It is during this season
that the greatest suspended particulate concentrations occur
according to the model. The model does not consider concentrations
of particulate matter from natural sources or from nearby urban areas
which combined to make up the background level in the area. For
this reason, the predicted concentration values shown in Figure 8
are not considered absolute. The model results are, however,
considered representative of suspended particulate dispersion patterns
created by emissions from the Indianapolis area source complex.
Figure 8 indicates the1 existence of a uniform pollutant diffusion
pattern centered on Indianapolis. Significantly high concentrations
of particulates occur in Morgan County (south of Marion County) in
the vicinity of a major point source. Source emissions are the
*See Appendix A for a more detailed discussion.
**Averaging times are as follows:
Winter: December, January, and February.
Summer: June, July, and August.
Annual: All 12 months of the year
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22
0 5 10 20 30 40 50
SCALE IN KILOMETERS
FIGURE 8. THEORETICAL SUSPENDED PARTICULATE CONCENTRATIONS
IN pG/M3, SUMMER AVERAGE.
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23
greatest for Morgan and Marion Counties (see Table I) and
ultimately affect the air quality over sizable portions of
Johnson and Hendricks Counties.
Theoretical sulfur dioxide concentrations are shown in Figure
9. Results for the winter season are presented since SC^ emissions
are greatest during that season and help to create the greatest
build-up of S0£ concentrations in the ambient air. A 3-hour
half-life for sulfur dioxide is used in the model as the assumed
rate of decay of S02. This produces values which correlate best
with measured concentrations. The sulfur dioxide concentrations
predicted by the model appear to be overestimated on the basis of
comparison with limited air quality data. The dispersion pattern
of above-background levels of SC^ is similar to that for suspended
particulates. A symmetrical pattern of SO^ equal concentration
contours is predicted for Indianapolis and immediately outlying
areas. A secondary peak of SC>2 concentrations occurs in Morgan
County at and near the site of the large point source referred to
above. As a result, a corridor of relatively high concentrations
occurs from Indianapolis south to include a large portion of
Morgan County and part of Johnson County.
Figure 10 shows predicted carbon monoxide concentrations based
on the summer averaging time. It is suring this averaging time
that greatest CO emissions occur. Partly as a result of this,
greatest CO levels are predicted to occur during the summer period.
As anticipated, concentrations are predicted to be highest in the
city of Indianapolis where vehicular traffic density is greatest.
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24
0 5 10 20 30 40 50
SCALE IN KILOMETERS
FIGURE 9. THEORETICAL S02 CONCENTRATIONS IN PIM, WINTER
AVERAGE (ASSUMED 3 HOUR HALF-LIFE).
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25
0 5 10 20 30 40 50
SCALE IN KILOMETERS
FIGURE 10. THEORETICAL CARBON MONOXIDE CONCENTRATIONS IN
PEM, SUMMER AVERAGE.
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26
Diffusion of carbon monoxide outward from the city of Indianapolis
appears to be uniform in all directions. The concentration gradient
decreases significantly at the 0.20 ppm isopleth. Portions of
Boone, Hamilton, Madison, Hancock, Shelby, Johnson, Morgan, and
Hendricks Counties are encompassed by the 0.10 ppm isopleth.
Pollutant transport does appear to be slightly greater toward the
northeast (Hamilton and Madison Counties) of the Indianapolis core
however, as reflected by the slight elongation of the isopleths in
that direction. This is logical since prevailing summer winds
are from the southwest.
SUMMARY
Specific conclusions can be reached with regard to the size
of the Indianapolis Region based on the consideration of pollutant
emissions and measured and predicted pollutant concentrations in
the ambient air. Total particulate and SC^ emissions are greatest
in Marion, Morgan and Hamilton Counties. Significant quantities
of particulate matter and S02 are emitted from a variety of source
types of Marion County. However, the primary sources of these
pollutants in Morgan and Hamilton Counties are power plants. Carbon
monoxide emissions are greatest in Marion County, and occur at
diminished levels in those counties contiguous to Marion County
(i.e., Boone, Hendricks, Hamilton, Hancock, Johnson, Morgan, and
Shelby Counties) .
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27
Available air-sampling data are not extensive enough to be of
much aid in determining the size of the Region. A diffusion model
has been used to predict pollutant concentrations in the ambient
air as an alternative to this lack of real air quality data. Equal-
concentration contours for SC^ and total particulates indicate that
peak concentrations occur in Marion and Morgan Counties while sizeable
portions of Johnson and Hendricks Counties are affected by lesser
pollutant concentrations. Peak carbon monoxide concentrations occur
in Marion County. Diffusion of CO appears to be uniform around
Marion County so that large areas of Boone, Hamilton, Hancock,
Shelby, Johnson, Morgan, Hendricks, and Madison Counties are
affected by carbon monoxide emanating primarily from the urban core.
In general, the air pollution problem in Indianapolis is not
confined solely to Marion County. Instead, this problem appears to
be common to Marion County and, with varying degrees of intensity,
to the counties of Boone, Hendricks, Morgan, Johnson, Shelby, Hamilton,
Hancock, and Madison.
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28
VAi-uAi :.w uf URBAN FACTORS
INTRODUCTION
The Air Quality Act of 1967 calls for the designation of air
quality control regions based on "jurisdictional boundaries, urban-
industrial concentrations, and other factors" in order to provide
for the adequate implementation of air quality standards. The
designation of air quality control regions must also be based on
a consideration of existing cooperative regional arrangements,
State and local air pollution control programs and enabling legis-
lation, and patterns and rates of urban growth.
POPULATION DISTRIBUTION
Existing and potential air pollution problems can be related
geographically to areas harbouring present or anticipated residential
and industrial development. Similarly, air pollution problem areas
can generally be identified by studying population statistics since
human activity is the basic cause of air pollution. Figure 11 shows
1968 population densities by county in metropolitan Indianapolis.
These population density figures (per sons/ square mile) are based
upon county land areas and total population, as listed in Table II.
At the present time, Indianapolis is the largest city in Indiana,
while Marion County is the States' largest county. Present
population in Marion County is approximately 762,000 persons, 515,000
of whom reside in the city of Indianapolis. The population of the
8-county Indianapolis SMSA (see Figure 14) is about 1,043,000 persons.
Thus, close to three- fourths of the total population in the 8 counties
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29
POPULATION DENSITY IN
PERSONS/SQUARE MILE.
>300
100-300
75-100
<75
0 5 10 20 30 ^0 50
SCALE IN KILOMETERS
FIGURE 11. 1965 POPULATION DENSITIES.
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TABLE II. PRESENT AND PROJECTED POPULATION DATA AND
MANUFACTURING EMPLOYMENT BY JURISDICTION
JURISDICTION
(County)
Bartholomew
Boone
Brown
Clinton
Decatur
De laware
Hamilton
Hancock
Hendricks
Henry
Johnson
Madison
Marion
Monroe
Montgomery
Morgan
Owen
Putnam
Rush
Shelby
Tipton
AREA
(Mi. )
402
427
324
407
370
398
401
305
417
400
315
453
400
410
507
406
390
490
409
409
261
1968 ESTIMATED
POPULATION
56,000
29,000
7,500
31,800
21,500
118,000
46,000
31,500
48,000
53,000
50,000
1.34,000
762,000
69,600
32,200
39,500
11,900
25,800
21,200
37,000
17,300
4 5
1980 PROJECTED
POPULATION
83,991
33,592
8,343
30,041
23,787
149,750
67,000
46,014
90,250
53,371
96,250
165,500
1,001,500
86,348
39,122
58,000
9,946
28,750
20,372
45,750
14,790
1968 POPULATION
DENSITY
(Persons/Mi.2)
140
68
23
78
58
296
115
99
115
133
159
296
1,905
170
64
97
31
53
52
90
66
I960 PROJECTED
POPULATION
DENSITY
(Persons/Ml.2)
209
79
26
74
64
376
167
151
217
133
306
365
2,500
210
77
143
25
59
BO
112
57
ADDITIONAL RESIDENTS
PER SQUARE MILE
1968-1980
71
11
3
-1
8
64
54
52
110
8
140
67
580
51
11
48
-4
6
0
22
-3
1963 MANUFACTURING
EMPLOYMENT
12,420
1,652
18
2,274
1,291
16,658
2,768
1,198
221
4,641
2,573
26,201
104,714
8,233
3,856
988
197
1,563
1,229
3,355
875
1963 MANUFACTURING
EMPLOYMENT DENSITY
(Persons/Mi.2)
31
4
*
6
3
42
7
4
*
12
8
58
260
20
8
2
*
3
3
8
3
*Negligible
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31
resides in Marion County, while one-half resides in Indianapolis.
Within the SMSA, and among those counties peripheral to Marion
County, total population and population densities are progressively
smaller in Johnson, Hendricks, and Hamilton Counties. Delaware and
Madison Counties, located northeast of the Indianapolis SMSA, contain
greater populations and population densities than counties within the
SMSA with the exception of Marion County. Over one-half of the total
population in each of these counties resides in the cities of Muncie
and Anderson, respectively. All other counties on the periphery
of the Indianapolis SMSA contain significantly less total populations
and population densities than either Madison or Delaware Counties.
Nineteen-eighty projected population densities by county are
shown in Figure 12. Population projections from which these densities
were derived are shown in Table II. In addition, Table II expresses
population growth by county, in terms of additional residents per
square mile, for the years 1968 to 1980. Marion County is expected
to undergo the greatest growth in population, followed by Johnson
and Hendricks Counties. Growth for these counties is projected to
be 580, 140, and 110 additional residents per square mile, respectively.
Bartholomew, Madison, Delaware, Hamilton, Hancock, Monroe, and Morgan
i
Counties, in that order, are projected to experience lesser though
significant increases in population. Shelby and Boone Counties, which
border Marion County, are expected to undergo relatively small
increases in population. Other outlying counties at present possess
relatively low population densities, and are projected to experience
only small population increases, or in some instances, population
decreases.
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32
POPULATION DENSITY IN
PERSONS/SQUARE MILE.
> 500
250-500
100-250
<100
0 5 10 '20 30 40 _50'
SCALE IN KILOMETERS
FIGURE 12. 1980 PROJECTED POPULATION DENSITIES.
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33
Generally, the Indianapolis area will show considerable
growth in the next 50 years, though it is difficult to predict
exactly where this growth will occur. It is expected, however,
that much of the growth will be in the counties bordering Marion
County. During the early 1960's Marion County experienced slight
out-migration. This is consistent with the trend showing that as
commuting time is decreased by better roads, people move to
surrounding areas. This will serve to increase the interdependency
between the Indianapolis core and outlying counties.
\
INDUSTRY
The location of industrial activity is helpful in determining
the size of an air quality control region since industrial sources
are major contributors of air pollutant emissions. Manufacturing
employment statistics have been used to determine the location of
industrial activity in the Indianapolis area. Figure 13 shows
1963 manufacturing employment densities by county drawn from the
total manufacturing employment statistics presented in Table II.
The statistics indicate that approximately 105,000 persons are
employed by manufacturing firms in Marion County; 70,000 of these
are employed in Indianapolis. Within Marion County, industrial
development has been closely associated with the transportation
network. Industry has developed along railroad lines and along
major highways. Also, a significant amount of industrial development
has occurred along the White River Valley where quantities of water
are available for industrial purposes. Madison County follows
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EMPLOYMENT DENSITY IN
PERSONS/ SQUARE MILE.
>50
25-50
5-25
<5
0 5 10 20 30 40 50
SCALE IN KILOMETERS
FIGURE 13. 1963 MANUFACTURING EMPLOYMENT BY COUNTY.
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35
Marion County in size as far as the number of manufacturing employees
is concerned. Delaware and Bartholomew Counties also harbour
significant numbers of manufacturing employees. All other counties
in the Indianapolis area, including those immediately surrounding
Marion County, contain relatively few manufacturing employees.
EXISTING REGIONAL ARRANGEMENTS
The prerequisite for Standard Metropolitan Statistical Areas
(SMSA's) is that they contain a core city of at least 50,000
persons and the county of that core city, as well as adjacent counties
which are found to be metropolitan in character and are economically
and socially integrated with the county of the central city. The
boundaries of the Indianapolis, Anderson, and Muncie SMSA's are
shown in Figure 14. The 1968 estimated populations of these three
SMSA's are 1,043,000, 134',000, and 118,000 persons respectively.
The Indianapolis SMSA includes Marion County as well as seven
surrounding counties (Boone, Hamilton, Hancock, Hendricks, Johnson,
Morgan, and Shelby). The Anderson and Muncie SMSA's include only
the county in which those cities lie (Madison and Delaware Counties
respectively). It appears that the social and economic influence
exerted by Indianapolis extends beyond the borders of Marion
County. At the same time, the Anderson and Muncie metropolitan
areas are distinct from metropolitan Indianapolis and from each
other.
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36
INDIANAPOLIS SMSA.
0 5 10 20 30 ^0 50
SCALE IN KILOMETERS
FIGURE 14. STANDARD METROPOLITAN STATISTICAL AREAS
IN THE INDIANAPOLIS AREA.
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37
Official State planning and development regions have been
established by the Governor of Indiana through Executive Order
No. 18-68. Fourteen such regions have been established throughout
the State of Indiana. These regions were defined by the Division
of Planning of the Indiana Department of Commerce on the basis of
physical contiguity, commuting patterns, newspaper circulation,
economic data such as income, employment and industry, as well as
upon a consideration of existing regional arrangements within the
State. These planning and development regions were established in
order to satisfy several objectives. First, they serve as an
organizational basis for data collection and analysis, and projection
of population, economic and social factors related to comprehensive
planning. Second, these regions serve to relate Federal programs
requiring regional coordination with appropriate plans and programs.
Also the planning regions will facilitate program coordination among
agencies at the State level. Finally, the planning and development
regions will provide a framework for regional planning and development
programs. In establishing these regions it was felt that a common
set of regions would provide a basis for coordination and cooperation
among Federal, State, and local agencies. The planning and development
region centered on Indianapolis is shown in Figure 15. This region
consists of Marion County and seven additional counties, and is
coextensive with the Indianapolis SMSA. Madison and Delaware Counties
are included along with five additional counties in a separate
planning and development region.
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38
0 5 10 20 30 40 50
SCALE IN KILOMETERS
FIGURE 15. INDIANAPOLIS PLANNING AND DEVELOPMENT
REGION. ':
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39
EXISTING AIR POLLUTION CONTROL PROGRAMS AND LEGISLATION
In the process of defining the bounds of an air quality
control region it becomes important to consider the role of
existing State and local air pollution control programs. It is
also important to review pertinent legislation which allows for
the promulgation of air pollutant control regulations and which
grants enforcement powers to agencies at the State and local
levels. Such consideration of existing programs is necessary
since it is upon them that the ultimate responsibility for
implementing region-wide air quality standards rests.
The 1961 Indiana Air Pollution Control Law (Chapter 171,
Acts of 1961) established an Air Pollution Control Board as an
independent enforcement agency, and authorized the State Board
of Health to consult with public and private groups, other States,
and the Federal Government to prevent air pollution. The original
Act has been amended by the Indiana General Assembly as set forth
in Chapter 357 of the Acts of 1969. The declared intention of the
Act is that primary responsibility for the control of air
pollution rests with local and air quality basin control programs.
\
The Act declares that this can be done most successfully by
focusing on goals to be achieved by a maximum of cooperation among
all parties concerned.
The Air Pollution Control Board is empowered to administer and
carry out the adjudicatory provisions of the Act and to make
investigations, consider complaints and hold hearings, and to make
such determinations as are necessary to carry out the purposes of
the Act. The Board may adopt rules and regulations consistent with
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40
the general intent and purposes of the Act. Rules and regulations
may be adopted which would create air quality basins based upon
scientific study of geographical, topographical, and meteorological
data. The Board may adopt and promulgate ambient air quality
standards for these air quality basins.
The State Board of Health is empowered to advise, consult,
and cooperate with other agencies of the State, towns, cities, and
counties, industries, other States, and the Federal government in
the prevention and control of new and existing air contamination
sources within the State. The Board of Health is also empowered
to encourage authorized air pollution agencies of towns, cities, and
counties to handle air pollution problems within their respective
jurisdictions to the greatest extent possible. It is also empowered
to render technical assistance to these local agencies to further
air pollution control.
The Act maintains provisions for towns, cities, and counties
to enforce local air pollution ordinances consistent with the
provisions of the Act, and permits them to enact and enforce more
restrictive ordinances to further the purposes of the Act. It
allows the board of commissioners of any county to enact and enforce
ordinances controlling air pollution, and further allows any city
or county within an air quality basin to administer its own air pollution
control program in cooperation with one or more towns, cities, or
counties. The failure of an air quality jurisdiction to enforce
local ordinances may prompt action by the Control Board to enforce
applicable provisions of the State law.
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41
In the city of Indianapolis responsibility for the control of
air pollution rests with the Bureau of Air Pollution Control. The
Bureau was established according to Air Pollution Control
Ordinance No. 140, dated 1951. The jurisdiction of the Bureau
encompasses the city of Indianapolis and that area within Marion
County four miles from the corporate boundaries of the city.
General Ordinance No. 115 (1952) prohibited the emission from
any stack of pollutants which might cause injury or nuisance to
any person or property at the risk of being enjoined by the courts
or abated by the Bureau. A new General Ordinance No. 109 dated 1967
was enacted to provide further provisions for the control of the
atmosphere in the Indianapolis area. According to this ordinance,
the duties of the Director of the Bureau are to receive and
institute complaints, institute enforcement actions, and cooperate
with Federal, State, county, and other agencies concerned with air
pollution. This Ordinance establishes the Indianapolis Air Pollution
Control Board which is empowered to establish air quality objectives
and to determine the need for specific controls to achieve and
maintain the desired air quality. The Board may make and amend
rules and regulations and set standards based on the need, technical
feasibility, and economic practicability. It also is empowered to
achieve compliance with the rules and regulations outlined in the
Ordinance.
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42
In summary, it appears that air pollution control legislation
enacted by both the State of Indiana and the city of Indianapolis
is based on a recognition of the value of cooperation between
control agencies at the various levels of government. Provisions
in the State Act allow for the creation of basins over which air
quality standards may be established. Thus, there is an awareness
at the State level of the value of controlling air pollution on a
regional basis. This concept is entirely compatible with the
efforts of the Federal government to establish regions over which
the air resource may be administered.
SUMMARY
The evaluation of urban factors indicates that an Indianpolis
Air Quality Control Region composed of the eight counties which are
members of a common State planning and development region (Boone,
Hamilton, Hancock, Hendricks, Johnson, Marion, Morgan, and Shelby
Counties) would satisfy the objectives for air quality control
region boundaries previously outlined. This eight county area has
been defined as a Standard Metropolitan Statistical Area, indicating
that these counties are economically and socially integrated with
the core city and county (Indianapolis and Marion) and with each
other. This eight county area has been established by the Governor
as a State planning and development region to provide a common
basis for cooperation and coordination among Federal, State, and
local agencies. Existing State air pollution control legislation
promotes and endorses such cooperation between control agencies at
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43
the various levels of government and between neighboring agencies
at the same governmental levels. It appears logical to designate
this entire eight county area for purposes of conducting a regional
effort toward air pollution control since the interdependence of
these counties has been established.
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44
THE PROPOSED REGION
Subject to the scheduled consultation, the Secretary,
Department of Health, Education, and Welfare, proposes to designate
an air quality control region for the metropolitan Indianapolis
area, consisting of the following jurisdictions in the State of
Indiana:
Boone County
Hamilton County
Hancock County
Hendricks County
Johnson County
Marion County
Morgan County
Shelby County.
As so proposed, the Metropolitan Indianapolis Intrastate Air
Quality Control Region would consist of the territorial area
encompassed by the outermost boundaries of the above jurisdictions
and the territorial area of all municipalities located therein and
as defined in Section 302(f) of the Clean Air Act, 42 U.S.C.
1857h(f). Figure 16 shows the boundaries of the proposed Region
while Figure 17 indicates the geographic relationship of the Region
to surrounding areas.
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45
0 5 10 20 30 ^0 50
SCALE IN KILOMETERS
FIGURE 16. PROPOSED METROPOLITAN INDIANAPOLIS INTRASTATE
AIR QUALITY CONTROL REGION.
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Niagara Frontier AQCR
Metropolitan Chicago
Interstate AQCR
rMetropolitan Pittsburgh
Intrastate AQCR
METROPOLITAN
INTRASTATE
CONTROL REGION
PROPOSED
CLEVELAND
AIR QUALITY
PROPOSED METROPOLITAN INDIANAPOLIS
INTRASTATE AIR QUALITY CONTROL REGIO
Metropolitan Cincinnati
Interstate
Metropolitan Stl Louis
Interstate AOOR
West Virginia
Figure 17 Relationship of Proposed
Metropolitan Indianapolis
Air Quality Control Region
to Surrounding Areas.
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DISCUSSION OF PROPOSAL
To implement a successful air resource management program, an
air quality control region should be sufficiently large so as to
encompass most pollution sources as well as most people and property
affected by those sources. The boundaries should also encompass
those locations where present and projected urbanization and
industrialization will create significant future air pollution
problems. Finally, the boundaries chosen should be compatible with
and foster unified and cooperative regional governmental administration
of the air resource. The proposed Metropolitan Indianapolis Region
was designed to best satisfy these requirements.
Designation of the eight county Indianapolis Region, as
proposed, will satisfy the objective that most pollutant sources
and receptors in a metropolitan area be included in the same air
quality control region. Greatest quantities of sulfur dioxide,
total particulate and carbon monoxide pollution are emitted, from
Marion County. Significant quantities of S02 and total particulates
are emitted from Morgan and Hamilton Counties. Carbon monoxide
emissions are evenly distributed among those counties contiguous
to Marion County (i.e., Boone, Hamilton, Hancock, Hendricks, Johnson,
Morgan, and Shelby Counties). Outlying areas of these'peripheral
counties contribute relatively low levels of pollutant emissions.
Diffusion model results reveal that the counties contiguous to
Marion County are receptors of pollutants of various concentrations
in the ambient air. Much of this pollution emanates from the city
of Indianapolis and from the remainder of Marion County.
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48
A review of population statistics and industrial activity
indicates that the proposed region is sufficient to accommodate
future expansion of both population and industry. As expected,
much of the population is and will continue to be concentrated in
Indianapolis and Marion County. Surrounding counties, and in
particular the areas of those counties furthest from Indianapolis,
have much lower population densities and industrial activity.
The eight-county Region proposed in this report coincides with
the Indianapolis Standard Metropolitan Statistical Area. It also
coincides with one of the States' fourteen planning and development
regions. Designation of this eight-county area as an SMSA and
planning region provides some indication of the interdependence of
these counties to one another and to the Indianapolis core. This
multi-county region should not be sub-divided insofar as regional
effort toward air pollution control is concerned.
Madison and Delaware Counties, to the northeast of Marion
County, contain two large cities (Anderson and Muncie respectively)
and a significant amount of population and .industry. There is some
relation of these areas (especially Madison County) to the
Indianapolis area both from the economic and social point of view.
These counties are not, however, closely enough related to metro-
politan Indianapolis either through "urban" factors or through a
common link based on the air pollution problem, to be included in
the Indianapolis Air Quality Control Region.
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49
As is true of most efforts to draw boundaries around an area to
differentiate it from its surroundings, there is always a likelihood
of boundary conditions existing or developing. In the case of air
quality control regions, such a boundary condition would exist where
sources of pollution on one side of the region boundary affect in
some real way air quality on the other side of the boundary.
Relocating the boundary would only rarely provide relief from this
condition. The solution is to be found in the way in which control
efforts are implemented following the designation of an air quality
control region. Consonant with the basic objective of providing
desirable air quality within the problem area being designated as
an air quality control region, the implementation plan that follows
the designation should have provisions for the control of sources
located close to but beyond the region boundaries. The level of
control for such sources should be a function of, among other
factors, the degree to which emissions from sources cause air
quality levels to exceed the standards chosen for application within
the air quality control region. The boundaries of the Indianapolis
Region were selected so as to minimize the pollutant transport
boundary problems mentioned above.
In summary, the Region proposed is considered on the whole to
be the most cohesive and yet inclusive area within which an effective
regional effort can be mounted to prevent and control air pollution
in the Indianapolis metropolitan area.
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50
REFERENCES
1. Public Health Service. Rapid Survey Technique for Estimating
Community Air Pollution Emissions. Publication No. 999-AP-29.
U. S. Department of Health, Education, and Welfare, Division
of Air Pollution, Cincinnati, Ohio, October 1966.
2. Public Health Service. Compilation of Air Pollutant Emission
Factors. Publication No. 999-AP-42. U. S. Department of
Health, Education, and Welfare, National Center for Air
Pollution Control, Durham, North Carolina, 1968.
3. Public Health Service. Air Quality Data from the National Air
Surveillance Networks and Contributing State and Local Networks,
1966 Edition. Publication No. APTD-68-9, U. S. Department of
Health, Education, and Welfare, National Air Pollution Control
Administration, Durham, North Carolina, 1968.
4. Rand McNally & Company. Commercial Atlas and Marketing Guide,
Ninety-Ninth Edition, 1968. Chicago, Illinois.
5. Graduate School of Business, Indiana University. Indiana
Population Projections 1965-1985, Volume I. Research Report
No. 3, September 1966.
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51
APPENDIX A. DESCRIPTION OF DIFFUSION MODEL.
The diffusion model is based on the Gaussian diffusion equation,
1 9 O /
described by Pasquill ' and modified for long-term averages ' for
application to the multiple-source situation typical of an urban complex.
The basic equation assumed that the concentration of a pollutant within
a plume has a Gaussian distribution about the plume centerline in the
vertical and horizontal directions. The dispersion of the plume is a
function of the emission rate, effective source and receptor heights,
atmospheric stablility and the distance from the source. The plume is
assumed to move downwind according to the mean wind.
The model was used to predict concentrations of SOo, and CO, and
total suspended particulates. The averaging times were the summer and
winter seasons and the year. In order that the theoretical pollutant
levels could be determined, it was necessary to-evaluate certain
meteorological input parameters. These parameters are wind direction and
frequency of occurrence in each direction, effective wind speeds for each
direction, and mixing depths for various averaging times.
Figure I-A shows the wind roses for the summer, winter, and year
for the Indianapolis area*. They represent graphically the frequency of
occurrence of the wind from the various compass directions. This data,
along with effective wind speeds for the respective compas directions
*U.S. Weather Bureau Data for Weir Cook Airport, 1951 through 1960.
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52
WINTER
SUMMER
ANNUAL
(INCLUDES ALL 4 AVERAGING PERIODS)
N
PER CENT FREQUENCY
OF OCCURENCE
FIGURE 1-A. WIND DIRECTION i'KR CENT FREQUENCY OF
OCCURENCE FOR VARIOUS AVERAGING TIMES.
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53
was used as input data to the computerized model. The characteristic
prevailing wind directions for each of the averaging times as depicted
by the length of the wind rose radials, produce a direct influence over
the dispersion of pollutants.
Table I-A shows average mixing depths for the winter, summer, and
annual averaging periods*. A significant diurnal variation in the mixing
depth is indicated. These mixing depths define the volume of air above
the surface through which pollutants are allowed to mix, and are assumed
to have no spatial variation (i.e., mixing depth is constant) over the
receptor grid system.
Table I-A.
Average Mixing Depths for Metropolitan Indianapolis
by Season and Time of Day (meters).
Season Morning Average Afternoon Average Average, Morning
and Afternoon
Winter
Summer
Annual
(four seasons)
430
320
390
700
1590
1262
565
955
826.
5,6
*Computed mixing depths documented by Holzworth and by recent tabulations
furnished to the Meteorological Program, NAPCA, by the National Weather
Record Center, ESSA.
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54
The diffusion model was used to compute the ground level
concentrations of pollutants at 225 receptor points. Their locations
were defined by an orthogonal grid system with mesh points 15
kilometers apart. This grid, 210 km. on a side, was centered in the
city of Indianapolis. An effective source height of 75 meters was
assumed for all pollutant point sources, while topographical
features were neglected for area-source emissions and for the 225
receptor points.
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55
APPENDIX A. REFERENCES
1. Pasquill, F. "The Estimation of the Dispersion of Windborne
Material," Meteorology Magazine, 90, 33-49, 1961.
2. Pasquill, F. Atmospheric Diffusion. Van Nostrand Co., New
York, New York, 190 pp., 1962.
3. Public Health Service. Workbook of Atmospheric Dispersion
Estimates. Publication No. 999-AP-26, Environmental Health
Series, U.S. DREW, National Center for Air Pollution Control,
Cincinnati, Ohio, 1967.
4. Martin, D.O., Tikvart, J.A. "A General Atmospheric Diffusion
Model for Estimating the Effects on Air Quality of One or
More Sources," Paper No. 68-148, 61st Annual Meeting, APCA,
St. Paul, Minnesota, June, 1968.
5. Holzworth, G.C. "Mixing Depths, Wind Speeds and Air Pollution
Potential for Selected Locations in the United States,"
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