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
       12
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.














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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.

 9.   Rihm,  A.,  Jr.  Air pollution and urban planning.  Health News.
     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.
     1958.

15.   Pooler, F. A.  Prediction model of mean urban pollution for use
     with  standard wind roses.  Int. J. Air and Water Pollution, 4:199-
     211.   1961.

16.   Koogler,  J.  B.,  et. al. A multivariable model for atmospheric
     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.
14

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