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
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Penalty for Private Use $300
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