Gulf War Illnesses: Preliminary Assessment of DOD Plume Modeling 
for U.S. Troops' Exposure to Chemical Agents (02-JUN-03,	 
GAO-03-833T).							 
                                                                 
Of the approximately 700,000 veterans of the Persian Gulf War,	 
many have undiagnosed illnesses. The Department of Defense (DOD) 
and the Central Intelligence Agency (CIA) have concluded, using  
computer plume modeling, that no U.S. troops were exposed to	 
hazardous substances because plumes--clouds of chemical warfare  
agents--could not have reached the troops. GAO was asked to	 
assess DOD and CIA plume modeling to determine whether DOD's	 
conclusions could be supported. GAO's final assessment will be	 
reported at a later date.					 
-------------------------Indexing Terms------------------------- 
REPORTNUM:   GAO-03-833T					        
    ACCNO:   A07060						        
  TITLE:     Gulf War Illnesses: Preliminary Assessment of DOD Plume  
Modeling for U.S. Troops' Exposure to Chemical Agents		 
     DATE:   06/02/2003 
  SUBJECT:   Armed forces abroad				 
	     Biological warfare 				 
	     Chemical and biological agents			 
	     Chemical warfare					 
	     Computer modeling					 
	     Disease detection or diagnosis			 
	     Diseases						 
	     Medical research					 
	     Military personnel 				 
	     Gulf War Syndrome					 
	     Persian Gulf War					 

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GAO-03-833T

Testimony Before the House Subcommittee on National Security, Emerging
Threats, and International Relations, Committee on Government Reform

United States General Accounting Office

GAO For Release on Delivery Expected at 1: 00 p. m. EDT Monday, June 2,
2003 GULF WAR ILLNESSES

Preliminary Assessment of DOD Plume Modeling for U. S. Troops* Exposure to
Chemical Agents

Statement of Keith Rhodes, Chief Technologist Center for Technology and
Engineering, Applied Research

and Methods

GAO- 03- 833T

This is a work of the U. S. government and is not subject to copyright
protection in the United States. It may be reproduced and distributed in
its entirety without further permission from GAO. However, because this
work may contain copyrighted images or other material, permission from the
copyright holder may be necessary if you wish to reproduce this material
separately.

DOD*s conclusion as to the extent of U. S. troops* exposure is highly
questionable because DOD and CIA plume modeling results are not reliable.
In general, modeling is never precise enough to draw definitive
conclusions, and DOD did not have accurate information on source term
(such as the quantity and purity* concentration* of the agent) and
meteorological conditions (such as the wind and weather patterns),
essential to valid modeling. In particular, the models DOD selected were
not fully developed and validated for long- range environmental fallout;
the source term assumptions were not accurate; the plume height was
underestimated; the modeling only considered the effects on health of a
single bombing; field- testing at Dugway Proving Ground did not
realistically simulate the actual bombing conditions; and divergence in
results among models.

DOD*s conclusion, based on the findings of epidemiological studies-- that
there was no significant difference between rates of illness for exposed
versus not exposed troops-- is not valid. In the epidemiological studies,
the results of DOD*s flawed modeling served as a key criterion for
determining the exposure classification* exposed versus not exposed to
chemical agents* of the troops. Such misclassification is a serious
problem that can have two types of effects: First, if misclassification
affects both comparison groups equally (nondifferential classification--
equally in the exposed and unexposed groups), it may water down the
results so that important associations are missed. Second, if
misclassification affects one group more than the other (differential
misclassification), it may introduce bias that obscures important
associations or creates false associations. Consequently, the
misclassification in the studies resulted in confounding* that is,
distorting* the results, making the conclusion invalid. Of the
approximately 700,000 veterans of the Persian Gulf War,

many have undiagnosed illnesses. The Department of Defense (DOD) and the
Central Intelligence Agency (CIA) have concluded, using computer plume
modeling, that no U. S. troops were exposed to hazardous substances
because plumes* clouds of chemical warfare agents* could not have

reached the troops. GAO was asked to assess DOD and CIA plume modeling to
determine whether DOD*s conclusions could be supported. GAO*s final
assessment

will be reported at a later date.

www. gao. gov/ cgi- bin/ getrpt? GAO- 03- 833T. To view the full product,
including the scope and methodology, click on the link above. For more
information, contact Keith Rhodes at (202) 512- 6412 or rhodesk@ gao. gov.

Highlights of GAO- 03- 833T, a testimony before the House Subcommittee on
National Security, Emerging Threats, and

International Relations, Committee on Government Reform

June 2, 2003

GULF WAR ILLNESSES PRELIMINARY ASSESSMENT OF DOD PLUME MODELING FOR U. S.
TROOPS* EXPOSURE TO CHEMICAL AGENTS

Page 1 GAO- 03- 833T Mr. Chairman and Members of the Subcommittee: We are
pleased to be here today to present our preliminary assessment of

the plume modeling conducted by DOD and CIA to determine the number of U.
S. troops that might have been exposed to the release of chemical warfare
agents during the Gulf War in 1990. We will report the final results of
this study at a later date.

As you know, many of the approximately 700,000 veterans of the Persian
Gulf War have undiagnosed illnesses since the war*s end in 1991. Some fear
they are suffering from chronic disabling conditions because of wartime
exposures to vaccines, as well as chemical warfare agents, pesticides, and
other hazardous substances with known or suspected adverse health effects.
Available bomb damage assessments during the war showed that of the 21
sites bombed in Iraq* categorized by intelligence agencies as nuclear,
biological, or chemical facilities* 16 had been destroyed by bombing. Some
of these sites were near the areas

where U. S. troops were located. When the issue of the possible exposure
of troops to low levels of chemical warfare agents was first raised,
during the summer of 1993, the Department of Defense (DOD) and the Central
Intelligence Agency (CIA) concluded that no U. S. troops were exposed
because (1) there were no forward- deployed chemical warfare agent
munitions and (2) plumes* clouds of chemical warfare agents* from the
bombing that destroyed the chemical facilities could not have reached the
troops.

This position was maintained until 1996, when it became known that U. S.
troops destroyed a stockpile of chemical munitions after the Gulf War in
1991, at a forward- deployed site, Khamisiyah, in Iraq. Consequently, DOD
and the CIA made several modeling efforts to estimate the number of troops
that might have been potentially exposed to chemical warfare agents. But
recognizing that actual data on the source term* such as the quantity and
the purity (concentration) of the agent* and meteorological conditions*
such as the wind and the weather patterns* were not

available, 1 DOD and CIA conducted field- testing and modeling of bombing
1 Observations were few because Iraq stopped reporting weather station
measurement information to the World Meteorological Organization in 1981.
As a result, data on the meteorological conditions during the Gulf War
were sparse. The only data that were

available were for the surface wind observation site, 80 to 90 kilometers
away, and the upper atmospheric site, about 200 kilometers away.

Page 2 GAO- 03- 833T sites at Khamisiyah, in 1996 and 1997, to determine
the size and path of the plume, as well as the number of U. S. troops
exposed to the plume. During

these initial modeling efforts, DOD asked the Department of Energy*s
Lawrence Livermore National Laboratories (LLNL) to also conduct modeling.
In 1997, DOD and CIA also combined a number of their own individual
modeling efforts into a composite and conducted additional plume modeling
of the bombing sites at Al Muthanna, Muhammadiyat, and Ukhaydir.
Subsequently, in 2000, DOD revised its modeling of Khamisiyah.

In our testimony today, at your request, my remarks will focus on our
preliminary findings of DOD and CIA plume modeling during the Gulf War.
Specifically, I will address the validity of the following DOD
conclusions:

 based on DOD plume modeling efforts, that the extent to which U. S.
troops were exposed was minimal and

 based on findings of government- funded epidemiological studies, that
there was no significant difference as to the rate of illness between
troops that were exposed to chemical warfare agents versus those not
exposed.

Our work thus far has involved interviews with agency officials and
experts in this area, reviews of relevant documents and literature, and a
review of DOD*s methodology and analyses of plume modeling. Our work has
been performed in accordance with generally accepted government

auditing standards. DOD*s conclusion as to the extent of U. S. troops*
exposure* based on DOD and CIA plume modeling* is highly questionable
because the results of the modeling are unreliable. In general, modeling
is never precise enough to draw definitive conclusions, and DOD did not
have accurate information on source term and meteorological conditions.

We have several reasons for this assessment: First, DOD selected models
that were not fully developed and validated for modeling long- range
environmental fallout. Second, some of the assumptions regarding the
source term data used in the modeling were not accurate* based on
incomplete information, data that were not validated, and testing that did
not realistically simulate the actual conditions at Khamisiyah. For
example, the CIA calculated the agent purity in 1991 to be 50 percent at
Khamisiyah, but 18 percent at Al Muthanna and about 15 percent at
Muhammadiyat. The CIA did not independently validate or establish agent
Summary

Page 3 GAO- 03- 833T purity levels based on empirically driven analyses,
and relied on UNSCOM reporting for these rates. This assessment of the
agent purity rate at Al Muthanna was questioned by a DOD official. We plan
to examine the

validity of the methodology used to calculated the rate of degradation.
Third, the plume height was underestimated, which resulted in discounting
the impact of certain meteorological conditions, such as high- speed winds
at nighttime, when many of the bombings occurred. This would have a
dramatic effect on the distance the chemical agent traveled. Moreover,
according to an internal DOD memo, plume height in one case at Al Muthanna
was arbitrarily determined by a DOD official to be 10 meters. At
Muhammadiyat and Ukhaydir, plume heights were estimated to be the height
of the munition or the munition stack. However, independent fieldtesting
demonstrated that a single 1,000- pound bomb would create plume height in
excess of 400 meters above the ground. Fourth, DOD, in its modeling, only
considered the effect of a single bombing of the sites on the health of
the U. S. troops. But DOD did not take into account the cumulative effects
of repeated bombings of the sites on troops* health. Fifth, post- war
field- testing done at Dugway Proving Ground, to estimate the source term
data and plume height, did not realistically simulate the actual
conditions of bombings at any of the sites. The simulation occurred under
conditions that were not comparable to those that existed at Khamisiyah.
For example, there were differing seasonal and meteorological conditions,
differences in rocket construction, and lesser

quantities of rockets. These differences result in multi- variable
uncertainty that cannot be resolved. Finally, there was a great divergence
among the various models DOD selected with regard to the size and path of
the plume and the extent to which troops were exposed. Combining the
results of various models masked the highly divergent predictions among
the individual models regarding the size and path of the plume. The
results of LLNL model which showed the largest area of coverage were
disregarded and not included in the composite model.

DOD*s conclusion that there were no significant differences in the rate of
illness between exposed and non- exposed troops is questionnable. DOD
based this conclusion on the findings of epidemiological studies, in which
DOD modeling was flawed. In addition, the modeling results served as a key
criterion for classifying troops that were ill and had been exposed
compared with troops that were ill and determined not to have been
exposed. However, the troops classified as non- exposed might have been
exposed. Such misclassification is a serious problem that can have two
types of effects. First, if misclassification affects both comparison
groups equally (non- differential classification* equally in the exposed
and

Page 4 GAO- 03- 833T unexposed groups), it may water down the results so
that important associations are missed. Second, if misclassification
affects one group

more than the other (differential misclassification), it may introduce
bias that obscures important associations or creates false associations.
Consequently, the misclassification in the studies resulted in
confounding* that is, distorting* the results.

In March 1991, after the conclusion of the Gulf War, U. S. Army demolition
units destroyed munitions at the Khamisiyah storage site* which included a
bunker and an open pit* in southeastern Iraq. Later, through inspections

conducted by the United Nations Special Commission (UNSCOM) in Iraq, it
was discovered that hundreds of 122- millimeter rockets destroyed at
Khamisiyah contained the nerve agents sarin and cyclosarin. U. S. and
coalition forces also bombed many other known or suspected Iraqi chemical
warfare research, materiel, storage, and production sites. According to
DOD and the CIA, coalition air strikes resulted in damage to filled
chemical munitions at only two facilities in central Iraq, Al Muthanna

bunker 2 and Muhammadiyat, and at the Ukhaydir ammunition storage depot in
southern Iraq. At Muhammadiyat, munitions containing an estimated 2.9
metric tons of sarin and cyclosarin and 15 metric tons of the chemical
agent mustard were damaged during the air strikes. At Al

Muthanna, munitions containing an estimated 17 metric tons of sarin and
cyclosarin were damaged during the air strikes.

According to DOD, the U. S. Government did not immediately make the
connection between the chemical munitions found by UNSCOM at Khamisiyah
and U. S. demolition bombings there. However, in 1996, concerns raised by
the Presidential Advisory Committee on Gulf War Illnesses prompted the CIA
to examine this issue. 2 The CIA contracted with the Science Applications
International Corporation (SAIC) to conduct the initial analysis and
modeling of the bombing of chemical munitions in Khamisiyah bunker 73. The
CIA*s first report, published in August 1996,

modeled the potential release of agents from bunker 73. The CIA and DOD
jointly published a second report in September 1997. In this report, they
combined the results of five different dispersions (for example, the size
and path of the plume) and meteorological models to determine the extent
of the plume from bombing of chemical munitions in Khamisiyah. In 2000, 2
The Presidential Advisory Committee on Gulf War Veterans* Illnesses was a
panel

established in August 1995 to provide oversight to Gulf War illnesses
investigations. Background

Page 5 GAO- 03- 833T DOD published the results of a new modeling of the
Khamisiyah site, using updated CIA source assessments and revising the
hazard area.

In chemical plume modeling, simulations are produced that recreate or
predict the size and path of the plume, including the potential hazard
area, and the potential effect on the health of the exposed population.
Modeling

requires accurate information on  source term characteristics, properties
(for example, vapor pressure,

flash point, size of particles, persistency, and toxicity information),
and rate of the agent release;  temporal characteristics of the period of
release (for example, whether

the initial release of chemical agent occurred during daylight hours when
it might rapidly disperse into the surface air or at night when differing
dispersion patterns would exist depending on terrain and the height of the
release);

 accurate collection of data that drive the meteorological models, such
as temperature, humidity, barometric pressure, dew point, wind velocity
and direction at varying altitudes, and other related measurements of
weather conditions during the modeled period;

 data from global weather models to simulate large- scale weather
patterns and from regional and localized weather models to simulate the
weather in the area of the chemical agent release and throughout the area
of dispersion; and

 information regarding the location of potentially exposed populations,
animals, crops or other assets that may be affected by releases of the
agent.

The modeling of various chemical agent releases during the 1991 Persian
Gulf War included global- scale models, such as the National Centers for
Environmental Prediction Global Data Assimilation System (GDAS) and the
Naval Operational Global Atmospheric Prediction System (NOGAPS). Regional
and local weather models used included the Coupled OceanAtmosphere
Mesoscale Prediction System (COAMPS), the Operational Multiscale
Environment Model with Grid Adaptivity (OMEGA), and the Mesoscale Model
Version 5 (MM5).

Transport and diffusion models (often simply called dispersion models)
were also used. They project both the path of the chemical agents after

Information Needed for Modeling the Effects of Chemical Warfare Agents
Types of Models Used

Page 6 GAO- 03- 833T release and the degree of hazard posed by the agents.
For example, the modeling of various releases during the 1991 Gulf War
included dispersion

models, such as the Second- order Closure Integrated Puff (SCIPUFF) model
along with its Hazard Prediction and Assessment Capability (HPAC)
component; the Vapor, Liquid, and Solid Tracking (VLSTRACK) model; the
Non- Uniform Simple Surface Evaporation Model (NUSSE); and the Atmospheric
Dispersion by Particle- in- Cell (ADPIC) model.

DOD*s conclusion as to the extent of U. S. troops* exposure* based on DOD
and CIA plume modeling* is highly questionable because the results of the
modeling are unreliable. The modeling conducted was not precise enough to
draw definitive conclusions regarding the size and path of the plume. We
found six reasons to question the conclusions: First, the models selected
were not fully developed and validated. Second, the assumptions regarding
the source term used in the modeling were not accurate. Third, the plume
height was underestimated. Fourth, DOD modeling only considered the
effects of a single bomb on health. Fifth, post- war field testing done at
Dugway Proving Ground did not realistically simulate the actual conditions
of bombing at any site. And, finally, there was a great divergence among
the various models DOD selected with regard to the size and path of the
plume.

DOD and CIA officials selected in- house models for use in plume modeling
(see appendix 1). In the case of Khamisiyah and other sites, DOD models*
such as the VLSTRACK and HPAC/ SCIPUFF dispersion models* were not fully
developed and validated for environmental fallout at the time of their
selection. In particular, these models were not appropriate for long-
range tracking of chemical agents.

VLSTRACK was developed primarily as a tactical decision aid for predicting
hazards resulting from the release of chemical and biological agents in a
military environment. Modeling experts at the Naval Surface

Center told us that the two- month DOD panel reanalysis and modeling was a
developmental effort because existing models did not have the capability
to perform the required projections. Considerations of potential illness
from low- level exposure to chemical agents resulting from nerve and
blister agents accidentally released in Iraq required extensive extensions
and modifications to some of the methodology in VLSTRACK.

HPAC was developed jointly by the Defense Intelligence Agency and the then
Defense Special Weapons Agency (now known as DTRA) and was specifically
tailored to do counterproliferation contingency planning. In a DOD*s
Conclusions Regarding the Extent of

Exposure of U. S. Troops Are Highly Questionable

The Models Selected Were Not Fully Developed and Validated

Page 7 GAO- 03- 833T 1998 scientific review and evaluation of SCIPUFF,
which is an integral part of HPAC, the National Oceanic and Atmospheric
Administration*s

(NOAA*s) Air Resources Laboratory stated that SCIPUFF is probably better
suited for short- range (about 10 kilometers) dispersion applications
rather than for long- range transport modeling. Among the limitations

cautioned regarding the use of the HPAC model are that does not provide a
definitive answer due to uncertainties about transport, location, and
weather.

In addition, based on the DOD modeling effort, it is evident that a group
using the VLSTRACK model might receive a significantly different
prediction from that of a group using the HPAC model. And neither of these
models has sufficient fidelity* that is, reliability* to permit the
conclusion that the actual hazard area* that is, path of the plume* is
confined to the predicted hazard area. In a September 1998 memo, the
Deputy to the Secretary of Defense for Counterproliferation and Chemical/
Biological Defense cited a DOD panel study team, which found that the
VLSTRACK and HPAC models generate hazard predictions that are
significantly different from each other. The memo noted, *This occurred
even when the source terms and weather inputs are as simple and as
identical as possible. In operational deployment, the average model user
could obtain different answers for the same threat.*

With regard to meteorological models, according to a 1997 memo from the
Director of NOAA*s Air Resources Laboratory to DOD, the selection of
models was dominated by in- house, that is, DOD, models that were not well
known outside of DOD. The Director noted that there were three mainstream
mesoscale models available and well accepted for deriving site- specific
flow conditions from large- scale meteorological information: MM5, RAMS,
and Eta. At that time, OMEGA and COAMPS were too new and not well accepted
outside of DOD circles. OMEGA was still under development, and a Peer
Review Panel on the 1997 Khamisiyah modeling reported that there were
major problems with the OMEGA model. For example, there were physically
impossible aspects to the OMEGA model solutions and major errors in its
simulations. For the analysis done for Khamisiyah and Al Muthanna, a DOD
technical review panel found that OMEGA consistently under- predicted
surface wind speeds by a factor of 2 to 3 when compared with actual
observations collected at five World Meteorological stations in the area.

There were significant uncertainties in the source term used in the plume
modeling at Khamisiyah. DOD and the CIA made assumptions about the source
term based on field- testing, intelligence information, imagery,

The Source Term Assumptions Were Not Accurate

Page 8 GAO- 03- 833T UNSCOM inspections, and Iraqi declarations to UNSCOM.
However, these assumptions were based on incomplete information, data that
were not

validated, and testing that did not realistically simulate the actual
conditions at Khamisiyah.

In its initial modeling of the demolition of chemical munitions at
Khamisiyah, the CIA did not have accurate and precise information as to
how rockets with chemical warheads would be affected by open pit
demolition, compared with bunker demolition. This lack of information
included the number of rockets, agent purity, and amount of agent released
in the atmosphere, agent reaction in an open- pit demolition, and
prevailing meteorological conditions. A DOD panel also found a lack of
information, 3 that is, substantial uncertainties regarding the number of
damaged rockets that might have released chemical agents and how fast the
nerve agents* sarin and cyclosarin, which were mixed together in the
rockets* were released. Some of these agents may have leaked from rockets
into the soil or into the wood of the boxes that contained the

rockets and evaporated over time. The panel also found that the CIA and
SAIC analyses used what were essentially guesses for the lack of data. For
example, the numbers of rockets were based on what was known to be there
before the demolition and what was found by the UNSCOM during their
inspections, but, according to a DOD panel, the numbers varied by a factor
of 5 or 6.

In addition, this panel recognized that meteorological data were limited
because there were relatively few observations, and these were made far
from the Khamisiyah site. Observations were few because Iraq stopped
reporting weather station measurement information to the World
Meteorological Organization in 1981. As a result, data on the
meteorological conditions during the Gulf War were sparse. The only data
that were available were for the surface wind observation site, 80 to 90
kilometers away, and the upper atmospheric site, about 200 kilometers
away. The panel also recognized that wind patterns could contain areas of
bifurcation* lines where winds move in one direction on one side and in

another direction on another side* which also move over time and are
different at different altitudes.

3 DOD had asked the Institute of Defense Analyses to set up a DOD- funded
panel to review the modeling.

Page 9 GAO- 03- 833T Source term assumptions on agents (sarin and
cyclosarin) purity established for the four sites* Khamisiyah, as well as
Al Muthanna,

Muhammadiyat, and Ukhaydir* differed widely. Discrepancies between the
Khamisiyah purity data and the Al Muthanna and Muhammadiyat data were not
adequately resolved. The agents were assumed to be purer in February 1991
at Al Muthanna than in January at Muhammadiyat and purer still in March at
Khamisiyah. In each case, agent purity was a key factor in the DOD and CIA
methodology for determining the amount of agents released. Since the
purity of the sarin and cyclosarin was used as a factor in calculating the
amount of agents released, purity is critical in compounding the
uncertainty of the modeling. For example, for modeling purposes, 10 tons
of agent with a purity of 18 percent would be represented as only 1.8 tons
of agent. The CIA did not independently validate or establish agent purity
levels based on empirically driven analyses, and relied on UNSCOM
reporting for these rates. This assessment of the agent purity rate at Al
Muthanna was questioned by a DOD official, who noted in a memo, *Why we
use the 18 percent purity instead of the 50 percent number available in
public sources, and why we treat GF like GB when there are documents that
mention the higher toxicity are not easily deferred with *because the CIA
says so. * I think the GF vs. GB numbers accepted by the EPA or CDC or
whatever is the competent authority, but the purity number is
problematic.* We plan to examine the validity of the methodology used to
calculated the rate of degradation. In addition, according to Iraqi
production records obtained by UNSCOM,

the agent purity at Khamisiyah, in early January 1991, was about 55
percent. The agent subsequently degraded to 10- percent purity by the time
laboratory analysis had been completed on samples taken by UNSCOM

from one of the rockets in October 1991. On the basis of the sample purity
and indications that the degradation rate for sarin and cyclosarin are
similar, the CIA assessed that the ratio of sarin to cyclosarin when the
munitions were blown up in March 1991 was the same as that sampled in
October 1991* 3: 1. According to the CIA, assuming a conservative
exponential degradation of the sarin and cyclosarin, the purity on the
date of demolition, 2 months after production, was calculated to be about
50

percent. At Al Muthanna, however, where the agent was stored in a bunker,
the CIA estimated the chemical warfare agent had deteriorated to
approximately 18 percent purity by the time that bunker 2 was destroyed,
in early February 1991, leaving about 1600 kilograms (1.6 metric tons) of
viable sarin. The CIA based its estimate on UNSCOM*s analysis of Iraqi
purity

Page 10 GAO- 03- 833T data and supporting information, which stated that
the munitions were filled with the agent in 1988 and that the maximum
purity for the 1988

agent was 18 percent in 1991. However, this assumption suggests knowledge
of exact production dates and storage conditions that were not
established. But UNSCOM and intelligence community reporting about the
near- wartime capabilities of Iraq suggests that while the sarin produced
was of poor quality, it had a maximum purity of 60 per cent. According to
CIA documents, the total amount of agent modeled to have

been released at Al Muthanna was 1 kg, but, to be conservative, the amount
released was assumed to be 10 kg. The reasoning given for the low amounts
discharged was the heat of the explosion. The CIA assessed that far less
agent would have been released in the Al Muthanna bunker because, based on
U. S. field- testing using simulated bunkers, heat would build up rapidly
in Iraqi bunkers made of thick reinforced concrete ceiling and walls,
thereby destroying most of the agent. However, these bumkers were targeted
using high explosives, such as Tomahawk missiles and laser- guided and
non- guided bombs, that detonate and produce instantaneous and extreme
blast forces and shock and pressure waves, as well as heat. While the CIA
analysts gave great credibility to the heat, no

consideration was given to either the blast effects of the munitions or to
the higher altitude plumes generated with the types of munitions used.

For Muhammadiyat, DOD also provided details regarding how they derived
source term characterizations for agent released using test data from
Dugway Proving Grounds. However, the types of munitions used in the
testing and, therefore, the resulting effects are not comparable to what
munitions were actually used and their effects. At Dugway Proving Grounds,
small explosive charges were placed on boxed rockets; at Muhammadiyat, the
munitions were targeted using multiple high- explosive bombs. Agent purity
at Muhammadiyat was estimated at 15 percent.

Plume heights from the explosions could be significantly higher than the
plume height assumptions provided for in the modeling of Khamisiyah and
other Iraqi chemical warfare sites. The plume height data the CIA provided
for the demolitions at the Khamisiyah pit was 0- 100 meters. However,
neither the DOD nor the CIA conducted testing to establish plume heights
associated with the bombings of Al Muthanna, Muhammadiyat, or Ukhaydir.
DOD modelers involved with the modeling efforts told us that they did not
calculate the plume height or any of the other heat or blast effects
associated with the bombings of these sites because DOD had provided the
modelers these data. A modeling expert from the Defense Threat Reduction
Agency (DTRA) told us that DOD data on plume height

The Plume Height Was Underestimated

Page 11 GAO- 03- 833T was inconsistent with other test data for the types
of facilities bombed. The modeling expert cited test studies conducted at
White Sands Proving

Grounds in New Mexico, which demonstrated plume heights would range from
300 to 400 meters in height.

Modeling experts from LLNL who participated only in the initial modeling
at Khamisiyah also told us, citing studies, that they questioned how the
plume height was estimated. In a pre- war analysis, LLNL projected that
the smoke source cloud, immediately following the bombing of Iraqi
chemical warfare agent facilities, would be characterized by a surface-
based plume with a 54 meter (177 ft.) horizontal radius and a height of
493 meters (1,617 ft.). A Sandia Laboratory empirical study, performed in
1969, established a power law formula for calculating plume heights
attributable to highexplosive detonations (see appendix II). Using this
formula, an MK- 84 or GBU- 24 (942.6lb. of high explosives) bomb would
generate a plume of 421 meters.

DOD applied the same assumptions about the height of the plume at
Khamisiyah to model other possible chemical releases at the Al Muthanna,
Muhammadiyat, and Ukhaydir sites. At Muhammadiyat, for example, DOD
established a release height of 0.5 meters (roughly half the bomb height)
for nerve agent and a release height of 1.0 meters (roughly half of the
median height of the various bomb stacks) for blister (mustard) agent
destroyed at this location. Moreover, according to an internal DOD memo,
an initial cloud size of 10 meters in both lateral and vertical directions
was *arbitrarily* established. No efforts were made by DOD to validate
these estimates by analyzing video images that were available showing some
of the plume data, particularly those taken from ground level at
Khamisiyah, were used to project the characteristics of the actual plumes.

As illustrated by figure 1, disparity in plume height source data could
result in vastly differing projections regarding how far the plume travels
and disperses, particularly during nighttime periods when a stable
(nocturnal) boundary layer emerges.

Page 12 GAO- 03- 833T Figure 1 Boundary Layer Characteristics

As also shown in figure 1, above the surface layer, in the stable boundary
layer, the winds often accelerate to higher speeds, in a phenomenon that
is called the low- level or nocturnal jet. At altitudes on the order of
200 meters above the ground, winds may reach 10- 30 meters per second (22-

67.5 miles per hour) in the nocturnal jet. Higher plumes than those
postulated by DOD, coupled with this phenomenon, could result in the rapid
transport of chemical agents until disturbed by turbulence or the return
of the mixed layer sometime after dawn. However, this possibility was not
taken into consideration in any of the modeling performed. Consequently,
the modeling may have resulted in underestimating the extent of plume
coverage. (For a detailed discussion of this issue, see appendix II.)

In addition, plume geometry associated with high- explosive discharges
shows that the majority of the mass of the plume is located toward the
higher altitudes, suggesting that the majority of the mass of the plume
would move to higher altitues where they might be transported by these
higher speed winds (see appendix III). Iraqi chemical warfare facilities
were bombed on several occasions, but

DOD and CIA modeling did not reflect the cumulative effects of these
repeated bombings on the amounts of agents released and on the health of

DOD Modeling Only Considered the Effects of a Single Bombing on Health

Cloud Layer 2000

1000 Convective Mixed Layer

Surface Layer Noon Sunset Midnight

Surface Layer Local Time Height (Meters)

Sunrise Noon

S1 S2 S3 S4 S5 S6

0 Entrainment Zone

Entrainment Zone Capping Inversion

Residual Layer Mixed Layer

Surface Layer Stable (Nocturnal) Boundary Layer

Free Atmosphere

Source: Roland B. Stull, An Introduction to Boundary Layer Meteorology,
(Boston, MA: Klumer Academic Publishers, 1988), p. 11.

Page 13 GAO- 03- 833T troops. For example, there were 17 distinct
coalition air strikes on the Muhammadiyat ammunition storage depot. While
modeling was requested for the duration of 72 hours after the chemical
release for Khamisiyah,

DOD used only a 24- hour duration for its modeling of the bombing of
Muhammadiyat. This was because at this site, unlike at others, DOD made
the assumption that all of the nerve agent was released at one time and
therefore modeled each air strike as if it was the only strike that caused
a release. According to DOD, each model produced a freeze frame of the

largest hazard area. The hazard area grows until it reaches its maximum
size, which the modeling suggests is about 10- 12 hours after the release.
DOD and the CIA also conducted post- war field- testing at Dugway Proving
Ground to simulate the actual bombing conditions at Khamisiyah to derive
the source term data for use in modeling. From May 1997 through November
1999, the testing center at Dugway Proving Ground conducted seven field-
testings and two laboratory studies to obtain source term data for use in
DOD and CIA modeling of Khamisiyah. For testing and

simulation to be effective, the conditions have to be as close to the
actual event as possible. However, the testing did not realistically
simulate the conditions that existed during the demolition of 122- mm
chemical- filled rockets in Khamisiyah and is therefore of questionable
usefulness in providing inputs data for the modeling. The simulations took
place under conditions that were not comparable to those that existed at
Khamisiyah. During the field- testing, there were differences in seasonal
and meteorological conditions; in munition crate construction material; in
rocket construction, including the use of concrete- filled pipes as rocket
replacements to provide (inert) filler to simulate larger stacks; the
fewer numbers of rockets (and therefore explosives) in the simulations,
which may have suppressed a potential chain reaction of explosions; the
use of agent simulant (rather than real agent); and soil. These
differences result in multi- variable uncertainty that cannot be resolved.

For example, the Dugway testing used a small sample of 32 rockets with
simulant- filled warheads to conduct seven field- testings: five were
singlerocket demolitions and two involved multiple- rocket demolitions.
One multiple- rocket trial demolition used nine functional rockets plus
three dummy rockets, while the other multiple- rocket trial used 19
functional rockets and five dummy rockets. In contrast, at the Khamisiyah
pit, stacks of 122 mm rockets, estimated to total about 1,250 rockets,
were detonated. Moreover, Dugway testing officials did not know whether
the 122 mm rockets used during the field- testings were the same as those
at the Khamisiyah pit. Dugway officials acknowledged that exploding a
larger number of rockets would make a significant difference on the
testing, and

Dugway Field- testing Did Not Realistically Simulate the Actual Bombing
Conditions

Page 14 GAO- 03- 833T aerial bombing with a heavy load would have a far
greater effect than was the case with the Dugway testing. According to DOD
and CIA analysts, the type of soil and wood can have a

significant effect on the dispersion of the agent. However, a Dugway
testing official told us that evaporation characteristics from the trials
and models were uncertain. DOD and CIA estimates of the evaporation and

retention rates of the chemical agent spilled on the soil may not be
similar to what was actually evaporated from and retained in the pit sand
at Khamisiyah. This is because while Iraqi soil was available and used in
the laboratory testing, it was not used during the field- testing.
Similarly, DOD and the CIA estimates of the amount of spilled agent that
evaporated from and was retained in wooden crates are suspect because
Dugway testing officials could not obtain actual wood from the Khamisiyah
pit site for testing. The aged and possibly damp wood at Khamisiyah would
absorb less agent than the new wood used at Dugway. DOD and CIA determined
that only about 32 percent of the agent was released and that most leaked
into the soil and wood with 18 percent of the leakage becoming part of the
plume (2 percent through aerosolization and 16 percent through
evaporation).

Field- testings were also conducted at a different time of the year and
time of the day than the actual Khamisiyah pit event. According to Dugway
officials, testing was done in May and in the early morning hours when
drainage conditions prevail. The U. S. demolition of the Khamisiyah pit
took place on March 10th, in the late afternoon during the presence of a
mixing layer. Other demolitions took place during evening and nighttime
hours when the stable (nocturnal) boundary layer emerges.

Despite the uncertainties in approximating the conditions that existed
even at Khamisiyah, DOD and the CIA used these data not only for the
Khamisiyah modeling, but also for the modeling of other sites. At all
these sites, the chemical warfare munitions would have been destroyed by
air strikes with much greater quantities of high- explosive charges and
under differing meteorological conditions.

DOD made no effort to resolve widely divergent modeling results among the
models selected. Instead, a composite model approach was taken, which
contributed to, rather than resolved, uncertainty.

For example, the DOD panel tasked the LLNL to conduct an analysis using
DOD*s MATHEW meteorological model with the ADPIC dispersion model. During
LLNL presentations to the DOD panel in November 1996 and

Divergence in Results among the Models

Page 15 GAO- 03- 833T February 1997, the LLNL provided a 72- hour
composite projection, assuming an instantaneous release of the contents of
550 rockets

containing sarin. It shows the plume covering an area extending
southsoutheast from the release point to the Persian Gulf, then turning
eastward at the Gulf coast, and then turning northeast over the Gulf and
extending northeastward across central Iran. (For a more detailed
discussion of this

topic, see appendix IV.) DOD models showed significant differences from
the LLNL assessment. In contrast to the LLNL modeling simulations,
analysis done with the DOD models* VLSTRACK with COAMPS meteorological
models and HPAC/ SCIPUFF with OMEGA meteorological forecasting models*
showed the plume from an instantaneous release moving first southerly, and
then turning to the west- southwest. See appendix V for a 72- hour plume
overlay of those composite projections published by DOD.

According to the DOD panel, no effort was made to reconcile the
differences between the DOD and LLNL modeling efforts. The panel
determined that the results were so different that it would not be
possible to choose the most affected areas and which U. S. forces were
affected. Accordingly, the panel recommended that a composite of the DOD
models be used to combine the hazard areas predicted by the models. Yet we
observed that even among the models selected for use by DOD, widely
differing paths were evident (see appendix VI).

Assuming that a composite modeling effort is an appropriate methodology, a
composite projection, including the above projections (DOD and CIA
composite and LLNL), would encompass a far larger number of forces and
seriously skew the outcome of any epidemiological studies done thus far,
as shown in figure 2.

Page 16 GAO- 03- 833T Figure 2: DOD Composite Projection and Lawrence
Livermore National Laboratory Projection

Page 17 GAO- 03- 833T A clear divergence exists in the predictions of the
models. Further research was conducted to determine whether there was data
available

that might explain this divergence. As a result of this research, the DOD
panel concluded that the divergence in the modeling outcomes may be
explained by a line of diffluence (directional split) in the independently
modeled 10- mm wind field data near Khamisiyah during the first 2 days of

the modeling period. The precise location of this line was critical to
which way the material would be transported by the wind. (See appendix VII
for an illustration of this diffluence with three different data sets).

In addition, DTRA officials told us that at the time of the modeling, they
conducted data- validation runs of the various models against visible
smoke plumes from the oil well fires in Kuwait; the runs showed a definite
bias, as shown in figure 3. According to DTRA, this validation could mean
that the uncertainty involved in using these models could result in an
angular shift of 10 to 50 degrees to the west. In other words, the actual
area coverd could be from 10 to 50 degrees to the east of the area
indicated by the model, meaning that it would cover a different population
from the one in the model.

Figure 3: Validation Runs of Various Models

Page 18 GAO- 03- 833T Given that the DOD modeling was flawed, DOD*s
conclusion, from epidemiological studies based on this modeling with
regard to rate of

illness among exposed versus not exposed, is questionable. Nevertheless,
the results of the modeling were used as a basis for determining the
exposure classification* exposed versus not exposed to chemical agents* of
the troops in population- based epidemiological studies. As we noted in
1997, to ascertain the causes of veterans* illnesses, it is imperative
that investigators have valid and reliable information on exposure,
especially for low- level or intermittent exposures to chemical warfare
agents. 4 To the extent that veterans are misclassified regarding
exposure, relationships would be obscured and conclusions would be
misleading.

Misclassification of study subjects in the measurement of the variables
being compared is a well- recognized methodological problem in
epidemiological studies. Misclassification can have two types of effects.
First, if misclassification affects both comparison groups equally
(nondifferential* equally in the exposed and unexposed groups), it may
water down the results so that important associations are missed. Second,
if misclassification affects one group more than the other (differential
misclassification), it may introduce bias that obscures important
associations or creates false associations. Consequently, the study
misclassification resulted in confounding* that is, distorting* the
results, making the conclusion questionable. By combining the results from
its individual modeling efforts, which

showed different areas of coverage, and ignoring the results of the LLNL
modeling, which showed much larger areas of coverage, DOD potentially may
have misclassified a large number of troops truly exposed to chemical
warfare agents in the putatively non- exposed group. If exposure to
chemical warfare agents truly caused adverse effects resulting in
increased hospitalization or death, such one- way misclassification would
tend to obscure the differences in hospitalization or death rates by
falsely increasing the rates in the putatively non- exposed group while
not affecting the rates in the exposed group.

4 GAO, Gulf War Illnesses: Improved Monitoring of Clinical Progress and
Reexamination of Research Emphasis Are Needed, (GAO/ NSIAD- 97- 163, June
23, 1997). DOD*s Conclusion from

the Epidemiological Studies Is Questionable

Page 19 GAO- 03- 833T Based on the June 1996 plume modeling, DOD officials
initially stated that only 300 to 400 troops were exposed to chemical
plumes. Based on

additional modeling, that number was revised to approximately 5000 on
September 1996; to approximately 20, 000 on October 22, 1996; and to
98,910 on July 23, 1997. DOD 2000 estimates place the number exposed at

101,752. The number from the October 22, 1997 plume model served as the
basis for informing approximately 100,000 Gulf War veterans of possible
exposure. This 1997 plume model was also used as the basis of at least two
epidemiological studies that were published in peer- reviewed scientific
journals.

In 2000 DOD announced that as a result of ongoing scientific analysis,
DOD*s Directorate for Deployment Health Support developed a new computer
model that changed the location of the Khamisiyah plume footprint. The
number of service members potentially exposed remained approximately
100,000. The new 2000 model reclassified 32,627 troops as unexposed who
were previously classified as exposed and classified 35,771 troops as
exposed who were previously classified as unexposed. Given the weaknesses
in DOD modeling and the inconsistency of data set* representing these
models* given to different researchers, there can be no confidence that
the research conclusions based on these models

have any validity. In evaluating the limitations of the plume modeling, we
concluded that even under the best of the circumstances, the results from
the modeling cannot be definitive. Plume modeling can allow one to
estimate what might have happened when chemical warfare agents are
released in the environments. Mathematical equations are used to predict
the activities of an actual event, in this case, the direction and extent
of the chemical warfare agent plume. However, in order to predict
precisely, one needs to have accurate information on the source term and
the meteorological

conditions. However, DOD did not have accurate information on the source
term or on meteorological conditions.

Given these modeling flaws, the DOD modeling results should not form the
basis for determining the extent of exposure of U. S. troops during the
Gulf War. The models selected were not fully developed and validated for

environmental fallout and the assumptions used to provide the input into
the models exhibited a preferential bias for a particular and limited
outcome. Yet even under these circumstances, the models failed to provide
similar conclusions. In addition, many potential exposure events were not
included. It is likely that if fully developed and validated models
Conclusions

Page 20 GAO- 03- 833T and more realistic data for source term were
included in the modeling, particularly plume height and exposure duration,
the exposure footprints

would be much larger and most likely to cover most of the areas where U.
S. and other coalition forces were deployed. However, given the weaknesses
in the data available for any further analyses, any further modeling
efforts on this issue would not be any more accurate and helpful.

In particular, source term data used for modeling the release of chemical
warfare agents during the Gulf War were inadequate for any model to
provide, with the desired accuracy and confidence, a single definitive
simulation of dispersion. Several modeling experts told us that if source
term inputs into modeling assessments are not accurate, the results of the
modeling would not be reliable The development of source term data was not
empirically driven, but rather driven by the subjective analyses of
individual intelligence agencies. No empirically driven analyses were
applied to determine plume height source data from the chemical warfare
agent research, production, and storage sites subjected to air strikes,
and no empirically driven calculations were disclosed regarding agent
purity as it affected the rate of decay of the chemical warfare agent
munitions that,

according to intelligence agencies reports, were produced immediately
prior to the war.

Efforts to simulate events and define the source term through testing were
unrealistic, conducted under inappropriate conditions and, in some cases,
inappropriately applied to dissimilar events. The subjective and defective
quality of much of the analyses conducted is best demonstrated by the

dynamic nature of the source data over time. That is, repeated analyses
resulted in continually changing conclusions and source data, despite the
fact that no aspect of the actual events changed after their occurrence.

DOD completely disregarded the results from the LLNL model which provided
divergent results, which were in the DOD and CIA modeling analysis. This
occurred despite a high degree of divergence, even among the selected DOD
models. Further, the precise plume projections of the LLNL model were
excluded from DOD*s composite modeling. Finally, in the DOD and CIA
composite model, divergence from individual models

was masked. Despite all of the uncertainties that emerged from DOD and CIA
modeling, the results of the modeling were used to serve as a basis for
determining the exposure status* exposed versus not exposed to chemical
agents* of the troops in population- based epidemiological studies.
However, given the weaknesses in DOD modeling and the inconsistency of
data set* representing these models* given to different

Page 21 GAO- 03- 833T researchers, there can be no confidence that the
research conclusions based on these models have any validity.

Mr. Chairman, this concludes my statement. I will be happy to answer any
questions you or Members of the Subcommittee may have.

Should you or your offices have any questions concerning this report,
please contact me at (202) 512- 6412 or Sushil Sharma, Ph. D., DrPH, at
(202) 512- 3460. We can also be reached by e- mail at rhodesk@ gao. gov
and sharmas@ gao. gov. Individuals who made key contributions to this
testimony were Jason Fong and Laurel Rabin. James J. Tuite III, a GAO
consultant, provided technical expertise. Contacts and

Acknowledgments

Page 22 GAO- 03- 833T On November 2, 1996, DOD requested the Institute for
Defense Analysis to convene an independent panel of experts in
meteorology, physics,

chemistry, and related disciplines to review the Khamisiyah modeling
analysis done by the CIA and its contractor, the Science Applications
International Corporation. The DOD panel recommended conducting additional
analyses using several DOD and non- DOD meteorological and dispersion
models as shown in table 1.

Table I. 1: Meteorological and Dispersion Models Used in Modeling
Khamisiyah Meteorological Model Developer/ Sponsor Dispersion Model
Developer/ Sponsor

Coupled OceanAtmosphere Mesoscale Prediction System (COAMPS)

U. S. Navy Hazard Prediction and Assessment Capability/ Second Order
Closure, Integrated Puff (HPAC/ SCIPUFF)

Defense Threat Reduction Agency Mass Consistent Wind Field (MATHEW)

Department of Energy/ Lawrence Livermore National Laboratory

Atmospheric Dispersion by Particle- in- cell (ADPIC)

Department of Energy/ Lawrence Livermore National Laboratory Mesoscale
Model, Version 5 (MM5) National Center for

Atmospheric Research Non- Uniform Simple

Surface Evaporation, Version 4 (NUSSE4)

U. S. Army Naval Operational Global Atmospheric Prediction System (NOGAPS)

U. S. Navy Vapor Liquid Solid Tracking (VLSTRACK)

U. S. Navy Operational Multiscale Environment Model with Grid Adaptivity
(OMEGA)

Defense Threat Reduction Agency Source: GAO. Appendix I: Khamisiyah Models

Page 23 GAO- 03- 833T A Sandia Laboratory empirical study performed in
1969 established a power law formula for calculating plume heights
attributable to highexplosive

detonations. This power law formula was derived from data on 23 test
shots, ranging from 140- 2,242 lbs. high explosives at U. S. Department of
Energy*s Nevada Test Site (National Exercise, Test, and Training Center)
and provides a cloud top height at 2 minutes after detonation. Most of the
shots were detonated during near neutral conditions, where the clouds
continued to rise after 2 minutes; data for 5 minutes after detonation on
some shots shows tops rising to nearly double the 2- minute values. The 2-
minute values better represent the final cloud top heights during stable
conditions.

This formula is represented as

h = 76( w 1/ 4 )

where h = height of plume in meters and, w = weight of explosives in
pounds

Using this formula, a MK- 84 or GBU- 24 (942.6lb of high explosives) bomb
would generate a plume of 421 meters:

H = 76 (942.6 pounds of high explosives) 1/ 4 H = 76 (5.541) H * 421
meters Figure II. 1 shows what the plume height trend line would be using
the formula to calculate plume heights, resulting from the detonation of
high explosives ranging in weight from 100 * 2, 000 lbs. Appendix II:
Power Law Formula

Page 24 GAO- 03- 833T Figure II. 1: Plume Height by Weight of Explosive

Page 25 GAO- 03- 833T As shown in figure III. 1, plume geometry associated
with high explosive discharges shows that the majority of the mass of the
plume is located

towards the higher altitudes, suggesting that the majority of the mass of
the plume would move to higher altitudes where they might be transported
by higher speed winds.

Figure III. 1: Examples of Various Plume Geometries

As shown in figure 3.2, the distribution of the plume geometry may be
affected by nocturnal jets. Appendix III: Plume Geometries and Wind

Transport

Page 26 GAO- 03- 833T Figure III. 2: Impact of Nocturnal Jets on Plume at
Higher Altitudes

In fact, empirical studies and actual reported and observed events tend to
refute DOD and intelligence agencies* assumptions and support the
alternative assumption of transport by low- level jets. First, empirical
testing suggests that the plume heights were much higher than postulated
in the source term data. Second, no massive casualties were claimed,

reported or observed in areas immediately surrounding the Iraqi chemical
warfare research, production, and storage sites bombed by coalition
forces. Third, since many of the bombings occurred at night, the explosive
effects coupled with higher altitude plumes and the presence of a
nocturnal boundary layer capable of moving hazardous materials hundreds of
miles could easily account for this phenomenon, as well as the reports of
chemical warfare agent detections in areas occupied by U. S. and coalition
forces. Fourth, the dynamics of advection explained above may account for
the reported wartime nighttime detections of very lowlevels of chemical
agents associated with turbulence mixing the upper and lower level
atmospheric layers resulting from aircraft- related sonic booms and
incoming missiles and artillery.

Page 27 GAO- 03- 833T The Department of Energy*s Lawrence Livermore
National Laboratory (LLNL) Atmospheric Release Advisory Capability was
tasked to conduct an analysis using its MATHEW meteorological model with
the ADPIC

dispersion model. Between 1979 and 2003, the LLNL modeling capability,
known as the Atmospheric Release Advisory Capability (ARAC), now the
National Atmospheric Release Advisory Center (NARAC), responded to more
than 100 alerts, accidents, and disasters, and supported more than 1,000
exercises. These include assessments of nuclear accidents, fires,
industrial chemical accidents, and terrorist threats.

During its presentations to the DOD panel in November 1996 and February
1997, scientists from Lawrence Livermore National Laboratory provided
plume projections based on the data provided by the panel staff. A number
of model projections were calculated and presented to the panel. As shown
in figure IV. 1, the LLNL 72- hour composite projection assuming an
instantaneous release of the contents of 550 rockets containing sarin. It
shows the plume covering an area extending south- southeast from the
release point to the Persian Gulf, then turning eastward at the Gulf
Coast, and then turning northeast over the Gulf and extending
northeastward across central Iran. Appendix IV: Lawrence Livermore
National

Laboratory Khamisiyah Simulation

Page 28 GAO- 03- 833T Figure IV. 1: Lawrence Livermore National Laboratory
Composite Projections

LLNL*s modeling assessment shows that the 72- hour exposure due to the
instantaneous release of sarin from 550 rockets covers a large hazard
area. According to LLNL, agent concentration in excess of the dosage
amount expected to cause *minimal effects* or symptoms on individuals
covered a 2,255 square km area extending approximately 130 km south-
southeast

Page 29 GAO- 03- 833T from the release point. 1 Dosages in excess of the
amount that would be allowed for a worker exposed to sarin in the
workplace, or the

*occupational limit, 2 * were predicted over a 114,468 square kilometer
area, including Kuwait City, an approximately 200 kilometer- wide area
across the Persian gulf, and the higher elevations of the Zagos mountain
range in Iran. The remaining area was determined to be at the *general
population limit.* 3 1 Minimal effects is the lowest concentration level
that would be expected to have

noticeable effects on human beings. 2 Occupational limit is about one-
tenth of the minimal effects value and is the maximum concentration level
that would be allowed for a worker who could become exposed to sarin in
the course of his job duties.

3 The general population limit represents the limit below which any member
of the general population could be exposed (e. g., exhale) 7 days a week,
every week, for a lifetime, without experiencing any adverse health
effects.

Page 30 GAO- 03- 833T A 72- hour plume overlay of those composite
projections published by OSAGWI is shown in figure V. 1. Figure V. 1: DOD
Composite Projection

Note: This projection includes the VLSTRAK and SCIPIFF/ HPAC dispersion
models with COAMPS, MM5, and OMEGA meteorological models. Appendix V: DOD
Model Simulations

Page 31 GAO- 03- 833T Even among the models selected for use by the DOD
panel, widely divergent directional outcomes were observed. As shown in
figure VI. 1,

differences can be seen among various models for hazard areas during the
first 2 days of the modeling period for Khamisiyah. Figure VI. 1
Divergence among Models Used in Constructing DOD and CIA Composite
Analysis The March 10, 1991 graphic demonstrates a 40- 45 degree
divergence

between the HPAC/ OMEGA and the HPAC/ COAMPS projections while the March
11, 1991 graphic demonstrates approximately an 80 degree divergence. The
uncertainty attributed to this divergence is not limited to the

Khamisiyah modeling. According to a modeling analyst involved with the
modeling of Al Muthanna, the weather models used, COAMPS and OMEGA, each
showed the plume going in different directions, at a 110- 120 degree
difference. The analyst said that COAMPS showed the plume going in a
North/ Northwest direction, while OMEGA showed the plume going South.
Similar divergence among model predictions was also observed in the
modeling of Muhammadiyat, as shown in figure VI. 2. Appendix VI:
Divergence among DOD Models

Page 32 GAO- 03- 833T Figure VI. 2: Divergence in DOD Models for
Muhammadiyat

Page 33 GAO- 03- 833T In figure VII. 1, windfield vector divergence
projections 6.0 meters above terrain are based on observational data
processed by the Meteorological Data Interpolation Code (MEDIC) model.

Appendix VII: Divergence and Wind Field Models

Page 34 GAO- 03- 833T Figure VII. 1: Lawrence Livermore National
Laboratory Diagnostic Wind Model Based on Observational Data In figure
VII. 2, the Windfield vector model based on European Centre for

Medium- Range Weather Forecast (ECMWF) projections, processed by the
Meteorological Data Interpolation Code (MEDIC) model, is shown.

Page 35 GAO- 03- 833T Figure VII. 2: Lawrence Livermore National
Laboratory Diagnostic Wind Model Based on ECMWF Projections

Page 36 GAO- 03- 833T In figure VII. 3, the windfield vector model is
based on Coupled OceanAtmosphere Mesoscale Prediction System (COAMPS)
Simulations at the

U. S. Naval Research Laboratories.

Page 37 GAO- 03- 833T Figure VII. 3: Windfield Vector Model Based on
COAMPS

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