United States
Environmental Protection
Agency
Industrial Environmental Research
Laboratory
Cincinnati OH 45268
Research and Development
EPA-600/S2-83-029  June 1983
Project  Summary
User's  Guide  for the Automated
Inhalation  Exposure
Methodology  (IBM)

F. R. O'Donnell, P. M. Mason, J. E. Pierce, G. A. Holton, and E. Dixon
  The  Inhalation Exposure Method-
ology (IEM) is a system of computer
programs that estimates atmospheric
transport and population exposure to
air pollutants. This summary describes
the components of the IEM system and
the types of modeling output it can
generate.
  This Project Summary was developed
by  EPA's  Industrial Environmental
Research Laboratory, Cincinnati, OH,
to announce key  findings  of  the
research  project  that is  fully
documented in a separate report of the
same title (see Project Report ordering
information at back).

Introduction
  The Inhalation Exposure Methodology
(IEM) is a system of computer programs
used  to estimate  atmospheric transport
of, and population exposure to, airborne
pollutants. IEM was developed to provide
automatic access to population  and
meteorological data   employed  in  a
sophisticated  but user-friendly
atmospheric dispersion modeling meth-
odology. Although results of IEM can be
applied to a number of different problems,
its principle use is estimating air pollution
concentrations and human inhalation
exposures in  the vicinity of hazardous
waste incineration facilities. IEM has
been  particularly effective in comparing
different pollution control techniques and
the   relative  importance  of  several
sources  of   facility   emissions.  IEM
employs  current  models  chosen  to
balance rigorous estimation techniques
with use of readily available data. IEM can
produce tables of annual average ground-
level   air concentrations,   population
distributions, and population exposures
via inhalation for pollutants emitted from
industrial sources.
  The IEM system installed on the IBM
computer at EPA's National Computer
Center, Research Triangle Park, North
Carolina, is accessible from any terminal
(remote or on-site) which can access the
system.
  IEM  consists  of four groups  of
computer programs (Figure 1) and several
permanently stored files of meteorolog-
ical and population data. The meteorolog-
ical  data group (MET) selects a meteor-
ological data set from permanently stored
files  containing National  Oceanic and
Atmospheric  Administration  Stability
Array (STAR) data, and formats the data
for use in  the atmospheric dispersion
program, which is  a slightly  modified
version  of  the  long-term  Industrial
Source  Complex  Dispersion  Model
(ISCLTM).* ISCLTM uses the meteorolog-
ical  data and other input to calculate
average ground-level air concentrations
of pollutants  emitted  from  sources
located at the site of interest. The popu-
lation data  group (POP) selects a site-
specific  population distribution from
permanently  stored  1980  Census
population data and formats it for use in a
concentration-exposure  program
(CON EX). CONEX takes the concentration
estimates from ISCLTM  and the popula-
tion  distribution from POP group and
prepares tables that describe the pollut-
ant   concentrations and population
exposures around the site. Each of these
steps is described in greater detail below.
*The ISCLT is one of the EPA's recommended air
quality models

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    MET Group
 Use EXE CO. EXEC1,
    and£XEC2
     ISCLTM
    Use EXEC6
    and EXEC7
                       POP Group
            Use EXEC3
            and EXEC4
               CONEX
             Use EXECS
             and EXEC7
            Output Tables
             Use EXEC7
Figure 1.
Schematic of program group
interactions in IBM.
  The flow of program execution and data
input in IEM are controlled by eight inter-
active executive (EXEC) routines run in
proper sequence.  Each EXEC routine
contains appropriate job-control program
statements which access system-stored
data files and programs, direct the user in
preparation of a  problem-specific input
data file, run the  program, and process
program outputs. The language used to
control an IEM  session  is  INTERACT
WYLBUR 6.0. Because some of these
programs must be run sequentially (as
described below) and have more than an
eight-hour turnaround time, four days a re
usually  required  to run  the  complete
system.

Coordinate Systems
  IEM  uses  two  polar coordinate
systems:  the  "grid" system  and  the
"centroid" system. Each system is char-
acterized by a set of radial distances to
rings circumscribed about the origin and
a common set of angles  representing
sixteen different vectors. The coordinate
systems  have a  common  origin. The
relative orientation of the coordinate
systems,  as built  into IEM, is  shown in
Figure 2.
  The "grid" system is represented by the
solid rings in Figure 2. Intersections of the
rings and the direction vectors (D1-D16)
mark   the  points at  which  ISCLTM
calculates  ground-level air concentra-
tions  (e.g.,  points  G1  and  G2).  The
"centroid" system is represented by the
broken rings.  Intersections of these rings
                                                               D16
                                                                                          D2
                                                    D15
                                                                                                     D3
                                             D14
                                           D12
                                                                                                              06
                                         D11
                                                                                           D7
                                                     D10
                             Figure 2.    The coordinate systems used in IEM.
                                                                               08
                             and the direction vectors (e.g., point C1)
                             locate the centers of  sector segments
                             (represented by the hatched area). The
                             POP  program  group  assigns  an
                             appropriate number of persons to each
                             sector segment and the CONEX program
                             calculates an average  air concentration
                             over each  sector  segment  using  the
                             adjacent  "grid"  concentrations. CONEX
                             then  combines  the  population and
                             average concentration values to calculate
                             exposures in each sector segment.


                             Program Groups
                             The MET (Meteorological Data)
                             Group
                               The  MET  group  consists  of  three
                             sequentially  executed  computer
                             programs, each  controlled  by  its own
                             EXEC routine. These  routines provide
                             step-by-step guidance for preparing  a
                             meteorological  data  set  for  use  by
                             ISCLTM.
                               The first program, SERCH (controlled
                             by EXECO), locates and identifies meteor-
                             ological weather stations near the  site
being  considered.  Stations  may  be
located by state or by latitude-longitude
window. Output from SERCH consists of
the five-digit station number, name and
location (city,  state, and latitude  and
longitude),  and the Federal Information
Processing Standards (FIPS) state code of
each station located in the search area.
The number of stations  located  in the
area is also indicated. The user notes the
station numbers  of all potentially useful
weather stations.
  Using the selected station numbers,
the second program, DIREC (controlled by
EXEC1), supplies a description of the
available  STAR   data  sets for  each
potentially  useful  weather station. In
addition to the information supplied by
SERCH, DIREC  lists  each  data  set's
header   number,  tape  location
information (i.e., starting record number,
number of records, and  tape number),
and  a  description   of the   data
contained   (e.g.,  time  period  covered,
seasons or months included, etc.). From
this information, the user can select a
data set for use by ISCLTM.

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  The  user   then  chooses  the
meteorological data set he will use and
supplies the information obtained from
DIREC to  the  next  program, STAR
(controlled by EXEC2), which formats the
chosen data set for use by ISCLTM. This
reformatted data set is stored in a semi-
permanent data file.

The POP (Population  Data)
Group
  The  POP  group  consists  of  two
sequentially  executed  computer
programs, each controlled by its  own
EXEC routine.  These  routines provide
step-by-step  instructions  for
transforming 1980  Census  population
data  into  a  site-specific  population
distribution for use by CONEX.
  The first program, RD80 (controlled by
EXEC3),  reads grid-recorded  1980
Census  population data  for the region
surrounding the site and transforms it
into a format  suitable for  use by  the
second program. Two types of data «ets
are available as permanently stored files.
A coarse grid (6'-latitude x 6'-longitude
rectangular matrix) data set contains
estimates of the number of persons con-
tained in each rectangle. Sets of fine grid
(2'-latitude x 2'-longitude rectangular
matrix) data contain estimates of  the
number of persons  living  in each rec-
tangle. Fine-grid data sets  are available
for  54 high-population  areas. To run
EXECS, the user must supply the latitute
and longitude of the site (the origin of the
coordinate systems), the radial distance
to the outermost "grid"  ring, and, if
applicable, the code name of the fine-grid
data set (listed in the user's guide). Output
from RD80 is stored as a semi-permanent
data file.
  The   second  program,  APORT
(controlled by EXEC4), is an adaptation of
a computer code written by Fields and
Little.1 After the user supplies, through
EXEC4, the number  of "grid" rings, the
distance of each ring, and the latitude and
longitude of the origin, APORT uses the
data file created by RD80 to produce the
population data file needed as  input  by
CONEX. This semi-permanently stored
data file contains the number of persons
located in each sector segment of the
"centroid" system.

The Atmospheric Dispersion
Program (ISCLTM)
  The atmospheric dispersion program,
ISCLTM, is a slighly modified version of
the  Industrial Source Complex Dispersion
Model—Long Term.2 This program esti-
mates the average ground-level air-con-
centrations of a pollutant at the "grid"
points around a site (one or more sources)
which  emits the  pollutant.  Input  to
ISCLTM  is  supplied  by the semi-
permanent   meteorological   data   file
produced by the  MET group  and an
interactively created  data file that is
prepared using EXEC6. The program is
run using EXEC7,  which also  controls
program outputs.
  The ISCLTM is a steady-state Gaussian
plume  model which can  account for
settling and dry deposition of particles,
downwash, and plume rise as a function
of downwind distance.  ISCLTM can be
used to simulate the dispersion of  non-
reactive  gases  or  of  those  reactive
gases which can be accounted for by an
exponential decay term. It is limited to flat
or gently rolling terrain; receptors are at
ground level at elevations not exceeding
source stack height, as discussed in the
final report.
  EXEC6  directs   the  user  in   the
preparation of a permanently stored input
data  file for use  by  ISCLTM.2 To
coordinate ISCLTM with the  other IEM
programs and to reduce the quantity of
interactively input data, many of the input
variables have been assigned preselected
values.  Most  pre-evaluated  variables
pertain   to  the   meteorological  data
descriptors.  Source, site,  and pollutant
variables must be entered by the user.
  Outputs  from  ISCLTM  include  the
standard ISCLT line printer output and the
temporary file used by CONEX.  The line
printer output lists the input data  and
gives  tables  of ground-level  air
concentrations   for  each  source
individually and for all sources combined.
The temporary file contains the "grid"
system  coordinates  and the  source-
specific concentration arrays.


The Concentration-Exposure
Program (CONEX)
  CONEX rewrites the source-specific
concentration estimates from  ISCLTM
into a variety of tables, including tables of
concentrations for  selectable  source
combinations; converts concentrations at
"grid" points (from ISCLTM) into average
concentrations over the sector segments
defined by the "centroid" coordinates;
prepares tables of sector segment  con-
centrations; multiplies  the  sector
segment concentrations by the number of
persons  in  the  corresponding sector
segments (from  APORT)  to  estimate
sector-segment  exposures;   prepares
tables of sector-segment exposures, and
calculates  and  tabulates  various
combinations  of  the  sector-segment
exposures.  Input data are supplied  to
CONEX from ISCLTM, APORT, and a user
prepared input data file that is created
interactively  using   EXECS.  Program
execution  and output is  controlled  by
EXEC7.
  EXECS asks the  user  to select the
desired  output tables. Available output
tables include a matrix of the number of
persons assigned  to   each  sector
segment; three sets of five tables, one set
describing  pollutant  concentrations  at
the "grid"  points,  one  set describing
average pollutant concentrations  over
each  sector segment,  and  one  set
describing  exposures in each  sectoi
segment; and four tables that summarize
exposures  by  source,  by sector and
source, by radial band and source, and by
concentration level and source.

Sample Calculations
  Besides describing how each program
of IEM  is accessed and the types anc
formats of the data which they produce,
the project report provides an example of
calculation  for a hypothetical incinerator
facility.  All   computer  interface
statements are shown, along  with the
data tables which are generated for this
particular example.

References
1.  Fields,  D. C., and C. A. Little. 1978.
    APORT —  A Program for the Area-
    Based  Apportionment  of  County
    Variables to Cells of a  Polar  Grid
    ORNL/TM-6418. Oak Ridge National
    Laboratory, Oak Ridge, Tennessee.

2.  Bowers, J. F., J. R. Byorklund, and
    C. S. Cheney. 1979. Industrial Source
    Complex (ISC)  Dispersion  Mode'
    User's   Guide   (Volume   1).  EPA-
    450/4-79-030.  U.S. Environmental
    Protection  Agency,  Research
    Triangle Park, NC.

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     F. R. O'Donnell. P. M. Mason, G. A. Holton, and E. Dixon are with Oak Ridge
       National Laboratory. Oak Ridge, TN 37830; J. E. Pierce is presently with EG&G
       ORTEC. Oak Ridge, TN 37830.
     B. L. Blaney is the EPA Project Officer (see below).
     The complete report, entitled "User's  Guide for  the Automated Inhalation
       Exposure Methodology (IEM)," (Order No. PB 83-187468; Cost: $ 13.00, subject
       to change) will be available only from:
             National Technical Information Service
             5285 Port Royal Road
             Springfield, VA 22161
             Telephone: 703-487-4650
     The EPA Project Officer can be contacted at:
             Industrial Environmental Research Laboratory
             U.S. Environmental Protection Agency
             Cincinnati, OH 45268
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Postage and
Fees Paid
Environmental
Protection
Agency
EPA 335
Official Business
Penalty for Private Use $300

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