AIR POLLUTANT EMISSIONS
| RELATED TO LAND AREA -
1 A BASIS FOR A PREVENTIVE
AIR POLLUTION CONTROL PROGRAM
iU.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
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950R68003
AIR POLLUTANT EMISSIONS RELATED TO LAND AREA-
A BASIS FOR A PREVENTIVE AIR POLLUTION
CONTROL PROGRAM
J. D. Williams, J. R. Farmer, R. B. Stephenson,
G. G. Evans, and R. B. Dalton
U.S. DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE
PUBLIC HEALTH SERVICE
CONSUMER PROTECTION AND ENVIRONMENTAL HEALTH SERVICE
NATIONAL AIR POLLUTION CONTROL ADMINISTRATION
Durham, North Carolina
July 1968
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The APTD series of reports is issued by the National Air Pollution
Control Administration to report technical data of interest to a
limited readership. Copies of APTD reports may be obtained upon
request, as supplies permit, from the Office of Technical Information
and Publications, National Air Pollution Control Administration,
U.S. Department of Health, Education, and Welfare, Ballston Center
Tower No. 2, 801 North Randolph Street, Arlington, Virginia 22203.
National Air Pollution Control Administration Publication No. APTD 68-11
ii
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ABSTRACT
Advances in technology have made it possible to establish zoning
performance standards, which will prevent air-use land-use conflicts.
In the past, such standards were based on source capability and were
uniformly inadequate. Now, because of the ability to predict air pollu-
tion levels, standards that accomplish both preventive and control aims
can be applied.
Land area, as used for urban planning purposes, reflects the diffu-
sion capability of the air in many areas. With the growing computer
capability and greater knowledge concerning the diffusion of pollutants
in the air, prediction systems are within practical application range.
An example of the output information from such a diffusion model is
discussed.
KEY WORDS: air pollution, air quality, air-use plans, diffusion model,
land use, performance standards, zoning
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AIR POLLUTANT EMISSIONS RELATED TO LAND AREA--
A BASIS FOR A PREVENTATIVE AIR POLLUTION
CONTROL PROGRAM
Before the turn of the century, the traditional and in some in-
stances the only way a community could alleviate air pollution problems
was by controlling the location of air pollutant sources by source
type. Although a source such as an "ironworks" would release the same
quantity and type of pollutants regardless of location, people recog-
nized that it was possible to arrange sources spatially so that receptor
areas were more likely to be open spaces or undeveloped land rather
than residential or otherwise developed districts.
Unfortunately, and for a multitude of reasons, the control of
source location did not always eliminate air pollution as a community
concern. Other influences were at work. As population grew, industry
expanded, and technology blossomed, source location became an impracti-
cal solution and other means of control became necessary. Control of
the source itself through technical devices developed as the prevailing
philosophy for control, as it still is today.
In the past, control of source location was accomplished largely
by royal decree or dictatorial fiat; now much the same thing is attempt-
ed by the instrument of zoning. Although zoning has never been directed
solely at controlling air pollution, those who were its early spokesmen
certainly had air pollution in mind.
Zoning in the United States is a rather recent development, with
the first comprehensive zoning ordinance being enacted in 1916 by New
York City. The concept of districting permissible land uses legisla-
tively (zoning) was first upheld by the U.S. Supreme Count in the land-
mark case of Euclid versus Ambler Realty Company in 1926. The majority
2
opinion, handed down by Justice Sutherland, stated, "A nuisance may be
merely a right thing in the wrong pi ace,--like a pig in the parlor in-
stead of the barnyard."
The principles enunciated in the Euclid case covered what Richard
3
May has described as the first era of zoning, "a period of control by
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location only." The basic zoning tool of this era, which is still in
vogue, is the "use list." Such a list indicates quite specifically the
land uses that are allowed or prohibited in each zoning district. Since
industry has become highly diversified and source control devices have
become more sophisticated, industry types and air pollution are no
longer bedfellows by definition alone. Many new industries - unknown
and unimagined 30 years ago are strictly nonpolluters. Attractive,
often idyllic, industrial parks are commonplace in the modern community.
They can be good neighbors while employing people and paying taxes. The
use-list approach, furthermore, cannot adequately take into account the
size of either the pollutant source or the plot of land on which the
source is located. For example, a large cattle lot would be treated
the same as a small one even though the small lot was on a site ten
times larger than the site of the large one. The use list has, with
time, become an over-simplified means of controlling air pollution and
is not sufficient for today's needs.
As a reaction to the inflexibility of the use list, several innova-
tions in zoning practices have brought us to a new era in the develop-
ment of zoning; emphasis is now placed on the performance level of
activities rather than just on the actual use of the land. This is the
concept of performance standards.
4
Dennis 0'Harrow, Executive Director of the American Society of
Planning Officials, outlined the basic performance standards concept in
his 1951 paper entitled, "Performance Standards in Industrial Zoning."
The paper presented 11 categories for which it was felt standards
should be developed:
1. noise 6. glare and heat
2. smoke 7. fire hazards
3. odor 8. industrial wastes
4. dust and dirt 9. transportation and traffic
5. noxious gases 10. esthentics
11. psychological effects
Standards for each of these 11 categories, suitably based on the
physical facts involved, would provide the maximum freedom to an air
pollutant source planning to locate in any particular air pollution
basin and would at the same time assure optimum conditions for residen-
tial and other land uses in that same basin. Obviously, the setting of
standards based on the physical phenomena involved is difficult and
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time consuming, but the air pollution category seems to lend itself well
to this type of treatment.
The Chicago zoning ordinance adopted in May 1957 was the first in
the country to apply a full scale of performance standards to industrial
zoning for a large urban area. Since then over 200 communities have
adopted performance standards covering categories originally suggested
by O'Harrow. Ideally, of course, zoning performance standards should
cover each of the four air-pollution-oriented categories: smoke, odor,
dust and dirt (particulates), and noxious gases. Many ordinances, how-
ever, deal only with smoke and particulates; and many more, unfortunate-
ly, apply only to the industrial districts of the community and not to
commercial or residential zones, which often contribute significant
quantities of pollutants to the atmosphere.
The validity and appropriateness of zoning performance standards
depend upon the diffusion capability of the atmosphere, which in turn,
is best reflected, for planning and zoning purposes, by the size and
nature of the land area from which the pollutants are emitted. If
standards apply only to what is emitted and if they bear no relation
to the concentration of pollutants already in the atmosphere or to the
land area involved, air pollution could be intolerable even though all
sources were fully controlled to a technically feasible level. In other
words, if technical feasibility rather than the diffusion capability of
the air is the principal guiding policy, increases in numbers and sizes
of sources would cause a continuing deterioration of the air quality.
Actually, the traditional zoning concept of districting permis-
sible uses and the more recent concept of location according to opera-
tional characteristics are neither in conflict with each other nor are
they mutually exclusive; they tend, in fact, to reinforce one another.
The one merely controls the location of uses, whereas the other pre-
scribes the allowable levels of operation and conduct of the uses.
In summary, zoning grew out of a need to limit the creation of
nuisances; it did this by providing a means whereby types of land uses
could be separated from conflicting uses while providing the land
owner and developer with an element of security as to the future use of
property. To some extent it helped the community plan services and
facilities, but it did not provide for the increase in air pollutant
source size or concentration of sources on a given unit of land, both
of which diminish the quality of the community-wide air supply.
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The development of land-use control techniques for air pollution
control purposes during the past 50 years leads to the conclusion that
we are now ready to proceed to a balanced use of regulatory programs
and planned air use, of which zoning performance standards are a part.
Such a program is directed toward accomplishing air quality goals that
are based on the effects of air pollution.
The increased demand by the people for a cleaner environment and
the increased capability of control devices to limit the emission of
pollutants at the source have made the use of performance standards
both more necessary and more appropriate. Their implementation is
further warranted by recent advances in establishing air quality
criteria, measuring air quality, and determining the atmospheric diffu-
sion capability.
The importance of meteorological parameters in city planning has
been known for a long time. Leavitt described the way Stalingrad in
Russia was laid out in two sections perpendicularly aligned to the
prevailing wind direction, resulting in a more favorable windward and a
less favorable leeward side to the town. Hilberseimer states that
when prevailing winds are so distributed that the section of pollution
dispersion does not exceed half a circle, a ribbon-like community is
possible. If the dispersion area does exceed half a circle, only fan-
shaped communities can be formed. Communities should be separated
from each other by the extension of the polluted area. A study by
o
Demarrais reported the meteorological information for the Tulsa Metro-
politan Area could be used in setting zoning performance standards and
requirements. The importance of meteorological considerations in
9 10
planning was also discussed by Rihm and Neiburger .
The location of sources on the basis of prevailing winds is a
simple and straightforward approach; however, it will not be effective
in many real situations. A more sophisticated treatment is necessary
in cases where the meteorology and topography complicate and abet the
air pollution problem. Such a technique utilizes a meteorological
diffusion model, which is a mathematical description of the meteorolog-
ical transport and diffusion process during a particular period, and an
inventory of emissions which yields estimates of air pollutant concen-
trations at specific locations.
Several models have been developed; each considers essentially the
same parameters, but in a different manner or time-scale. The
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complexity of the models varies from very simple hand calculations,
described by Clarke, to a complex computer program, described by
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Turner. Several other models are also described in the litera-
ture.13'17
The basis for the mathematical treatment of an air pollution basin
is easily understood if the basin is thought of as an area within which
pollutants are emitted and receptors are affected by distance and
diffusion conditions. The boundaries of the basin are defined in a
pollutant-concentration - effects concentration manner since the con-
centration of pollutants decreases with increasing distance from the
source or sources, even though the source area itself may be specifi-
cally defined. For a certain air pollution concentration (air quality)
at any point within the basin, only a certain quantity of pollutants
(emissions) can be put into the air.
There are two major considerations regarding the amounts of pollu-
tants that may be emitted. First, a high pollutant emission rate will
produce an excessively high concentration in a limited area. Any air
pollutant receptor exposed to such pollutant concentrations could find
this exposure undesirable even though conditions in the rest of the
basin would be satisfactory. Second, when averaged over a considerable
period of time, the air quality will be the same over relatively large
areas. Air pollution effects are associated with each of the described
conditions, and control should be designed for the appropriate time-
concentration conditions (or other pollutant dosage indicators) selected
from statistical frequency-distribution diagrams of pollutant concentra-
tions to prevent both high-concentration, short-exposure and low-con-
centration, long-exposure effects. The prevention of high-concentra-
tion, short-exposure effects applies to any source regardless of
location. The prevention of low-concentration, long-exposure effects
may apply to any source, but is more apt to apply to those sources
significantly affecting the same receptor areas.
A diffusion model has many potential uses. It can assist in pre-
diction of pollutant concentrations on a day-to-day basis for air
pollution warning and alert systems. It can help regulatory programs
justify certain regulations by determining the proportion of air pollu-
tion concentrations attributable to each source or type of source. It
can help in selection of sites for major pollutant sources and effective
planning of new cities or renewal of existing ones. It can help define
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the limits of control districts. It can help in the preparation of
air-use and land-use plans to preserve or achieve clean air while at
the same time allowing industrial and other related developments.
Because of the many calculations, diffusion models can be applied
to multisource problems only by means of computer programs. The pro-
gram being used for illustration purposes herein calculates long-term
average (season or year) ground-level pollution concentration in parts
per million (ppm) at one or more receptor points from a single source.
The required inputs to the model are the grid coordinants of pollutant
sources, grid coordinants of receptor points, stack heights of sources,
pollutant emission rates, and meteorological data. This particular dif-
fusion model is still under development and has not been validated by
field data as yet. It is being validated, but in the meantime its use
is limited to analysis of certain problems only.
The model was programmed for the IBM 1130 digital computer FORTRAN
IV language. The meteorological data used in the example were from
Lambert Field in St. Louis, Missouri. The meteorological conditions of
other areas would not be directly comparable to those presented. The
emission data were selected arbitrarily and do not represent any com-
munity in the United States. The example uses sulfur dioxide as the
pollutant, but the model is not limited to that pollutant alone. Any
gas or small sized particulate can be treated, although inaccuracies in
the model and differences in pollutant behavior such as decay rates and
secondary pollutants resulting from reactions in the air must be allowed
for when interpreting the results.
The example utilizes the meteorological data shown in Figure 1, the
area shown in Figure 2, and the data in Table 1. The city, highly
simplified and hypothetical for demonstration purposes, has a population
of 2,000,000 people and encompasses 165 square miles. The land is
zoned for industrial, commercial, multifatnily residential, and single-
family residential use.
The area has two power plants. Plant A is situated on a 20-acre
plot and has a 100-meter stack. The plant burns both coal and residual
fuel oil and has a generating capacity of 1000 megawatts. Power plant
B burns coal only, is located on a 5-acre plot, and has a generating
capacity of 500 megawatts. It has a 50-meter stack. The rates of
emissions in grams per second and equivalent tons per acre per month are
shown in Table 1.
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Table!. CHARACTERISTICS OF EXAMPLE CITY5
Source type
Commercial
Industrial
Residential
Multi family
Single family
Power plant A
Power plant B
Sulfur dioxide emission,
g/sec
655
2,280
70
--
4,660
2,340
tons/acre/mo
1.14 x 10'3
0.53 x 10"3
0.034 x 10'3
--
665
1,348
Total area, 105,600 acres; population, 2,000,000.
Figure 3 indicates the predicted sulfur dioxide concentration at
ground level from all sources. Note that the highest concentration
falls over part of the commercial area and extends in the direction of
the industrial area encompassing power plant B and extending in the
direction of power plant A. Note also the sulfur dioxide sampling
station near the center of the commercial area.
Figure 4 shows the contributions of the power plants only. They
account for 50 percent of the sulfur dioxide concentrations in the
central part of the area. To a considerable extent, this is caused by
the 50-meter stack height of power plant B.
Figure 5 shows the industrial contribution, which extends out from
the industrial area. The industrial pollution pattern indicates that
an adjacent buffer zone would be advantageous.
Figure 6 indicates the contribution of the multifamily residential
area to sulfur dioxide concentrations at ground level. Because of low
stack heights, the commercial area contributes significantly to sulfur
dioxide concentrations at ground level in the central zone. Figure 7
indicates these contributions to be approximately 40 percent of the
total concentrations. If the problem in this area is to be solved,
emphasis must obviously be placed on control of commercial emissions
and power plants, at least the one with a relatively low stack located
in the residential and multifamily area.
A sulfur dioxide sampling station located in the center of the
commercial area could provide a check on the predicted concentrations
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of the meteorological diffusion model. The model can predict the
ground-level concentrations contributed by the pollutant emissions from
each source or source category. If the sum of the concentrations from
each source or source category equals the actual concentration measured
at the sampling station, the model can be considered valid and consid-
erable trust can be placed in its predictions. In real situations,
however, several sampling stations are required to validate a model for
a particular area. Since one of the major uses of the predictions is
to indicate the relative amounts of pollution caused by certain sources
or categories of sources, the prediction system has considerable immedi
ate use. As time goes on and results of research can be applied, more
effective diffusion models will lead to greater use and reliability.
Additional community experiences will also improve the validity of
diffusion models and in time will lead to application of cost analysis
and related decision-making facts. It must be repeated, however, that
this model as presently constituted is still in the development stages
and applies to long-term averages. Not all effects are associated with
long-term averages; in fact, the effect on vegetation may result from
only a 30-minute exposure. The engineering analysis and application
must, therefore, take into account short-term as well as long-term
effects.
A computer programmed diffusion model can be part of the "cement"
between regulatory and urban planning agencies as well as state and
local levels of government. It will help make decisions for clean air
for urban areas and provide for the logical development of industrial
and other resources.
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NVI NNW
88. 6.2 57
Figure 1. Percentage frequency of wind direction
at Lambert Airport in St. Louis, Mo.,
Dec. 1, 1964 Feb. 28, 1965.
4BO 500 520 540 560 58C
'EQUALS 1.0.000 ft
I I SINSLE-FAIIILV RESIDENTIAL MEA
S^Q INDUSTRIAL AREA
IMIIIIII MJLT1FAKILY RESIDENTIAL AREA
l*V>V./t COMMERCIAL AREA
D POttR PLANT A - LOCATED CENTER OF 20-ACRE PLOT, 100-METER STACK
• POKER PLANT B - LOCATED CENTER OF 5-ACRE PLOT. 50-KETER STACK
A SAMPLING STATION
Figure 2. Model city layout.
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' ' EQUALS 10.000 ft
I I SINGLE-FAMILY RESIDENTIAL AREA
B&S INDUSTRIAL AREA
HM1MI MULTIFAMILV RESIDENTIAL AREA
r?7r* COMMERCIAL AREA
D POKER PLANT A - LOCATED CENTER OF 20-ACRE PLOT, 100-METER STACK
• POWER PLANT B - LOCATED CENTER OF 5-ACRE PLOT, 50-METER STACK
A SAMPLING STATION
Figure 3. Predicted total S02 concentration (ppm)
from all sources for 3-month period
Dec. 1, 1964 - Feb. 28, 1965.
\
N
\
' ' EQUALS 10,000 ft
O POWER PLANT A - LOCATED CENTER OF 20-ACRE PLOT, 100-METER STACK
• POWER PLANT B - LOCATED CENTER OF 5-ACRE PLOT, 50-METER STACK
A SAMPLING STATION
Figure 4. Predicted S02 concentration (ppm)
from public utility power plants
only for 3-month period Dec. 1,
1964 Feb. 28, 1965.
10
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460 500
-. EQUALS 10.000 ft
3 INDUSTRIAL AREA
A SAMPLING STATION
Figure 5. Predicted S02 concentration (ppm)
from industrial sources only for
3-month period Dec. 1, 1964
Feb. 28, 1965.
JO
4S
0
1
\
so
/^1
s
1
\
\\
\
0
— -N.
.• —
/
1
s
V ^
V V
^^
T^-4
" "7
im^j
^)
HUlW
^^
V.
X^
%
^
\
)
,/
y
/
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"
PTTIlll HULTIFAHILY RESIDENTIAL AREA
A SAMPLING STATION
Figure 6. Predicted S02 concentration (ppm)
for 3-month period Dec. 1, 1964 -
Feb. 28, 1965, from multifamily
residential area only.
11
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460 460
• 1 EQUALS ID,ODD ft
COMMERCIAL ABE«
A SAMPLING STATION
Figure 7. Predicted total SOg concentration
(ppm) for 3-month period Dec. 1,
1964, to Feb. 28, 1965, from com-
mercial area only.
12
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REFERENCES
1. Haar, C. M. Land-use planning: casebook on the use, misuse, and
re-use of urban land. Little, Brown and Company, Boston. 1959.
p.148.
2. Ibid., p.162.
3. May, R., Jr. The proper role of planning and zoning in air pollu-
tions controls. Presented at the National Conference on air pollu-
tion, Washington, D. C. 1958. p.l.
4. O'Harrow, D. Performance standards in industrial zoning. American
Society of Planning Officials. Chicago. 1954.
5. Schulze, E. E. Performance standards in zoning. JAPCA, 10:156-60.
1960.
6. Leavitt, J. M. Meteorological considerations in air quality plan-
ning. JAPCA, 10:246-50. June, 1960.
7. Hilberseimer, L. The nature of cities. Paul Theobold and Company,
Chicago. 1955.
8. DeMarrais, G. A. Meteorology for land development planning in the
Tulsa metropolitan area. Technical Report A61-5, U.S. Department
of Health, Education, and Welfare, Cincinnati, Ohio. 1961.
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New York State Department of Health, Albany, N. Y. Nov. 1962.
pp.15-19.
10. Neiburger, M. Meteorological aspects of air pollution control.
Yale Scientific Magazine. Jan. 1967.
11. Clarke, J. F. A simple diffusion model for calculating point con-
centrations from multiple sources. JAPCA, 14:347-52.
12. Turner, D. B. A diffusion model for an urban area. J. Applied
Meteorology, 3:83-91. Feb. 1964.
13. Lucas, D. H. The atmospheric pollution of cities. Int. J. Air
Pollution, 1:71-86. 1958.
14. Meade, P. J., and F. Pasquill. A study of the average distribution
of pollution around Straythorpe. Int. J. Air Pollution, 1:60-70.
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15. Pooler, F. A. Prediction model of mean urban pollution for use
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dispersion predictions. JAPCA, 17:211-14. April 1967.
13
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17. Miller, M. E., and G. C. Holzworth. An atmospheric diffusion
model for metropolitan areas. JAPCA, 17:46-50. Jan. 1967.
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