One focus of concern about the exposures that might have led to adverse health effects has been the possibility of their exposure to chemical and/or biological weapons. Saudi Arabia during both Desert Shield and Desert Storm was an environment in which there was a significant threat that this unfamiliar class of weapons might be used. The troops were very aware of the chemical and biological threat, and were nervous about it. Iraq had developed several types of chemical weapons, and had previously used sulfur mustard (HD, a blister agent) and nerve agent in the war with Iran. It had publicly threatened the use of chemical weapons in the Gulf War. It was also believed to have an active program developing biological weapons (in particular, anthrax and botulinum toxin). Many of the coalition forces expected to encounter chemical and/or biological weapons, and had trained extensively for this encounter. This tension and anticipation resulted in clusters of alarms and warnings, anecdotal stories and rumors concentrated in the periods in which the tempo of the war increased (the start of the air war, and again starting just before the ground war.) The figure below illustrates the increase in the number of reports logged within the NBC (Nuclear, Biological and Chemical) cells of the Central Command, Army Central Command and VII Army Corps.

logged chemical or biological reports processed

Careful analysis by the Coalition forces following Desert Storm led to the conclusion that there was no intentional, tactical use of either biological or chemical weapons by Iraq during the war. More recently, however, the possibility has been recognized that there might have been other types of releases of chemical or biological agents, most plausibly during bombing of Iraqi munitions bunkers or production facilities. This section summarizes an analysis, drawn from information collected predominantly from U.S. sources, but with corroboration from British sources, of evidence relevant to possible exposures of U.S. forces to biological and chemical agents.

1. Biological Agents

Biological agents are easily recognized through their effects on a target population. The effects of the two most likely Iraqi agents--botulinum toxin and anthrax--are very well understood and easily recognized.

Table 15

Biological Agent Symptoms/Effects Likely

Anthrax, in particular, can be immediately identified in an afflicted individual, both by symptoms and by direct detection of the organism. There were no reported cases of botulinum toxicity or of infection by anthrax (although anthrax is enzootic in that region of the Gulf, and is the occasional cause of death in animals). Examination of bunkers in the southern and eastern parts of Iraq (that is, the part closest to the U.S. forces) after the war revealed no biological weapons, and no evidence that they had been deployed and then retrograded. Inspections in the post-war period by UN biological weapons teams found no weaponized stores of toxins, spores or organisms (although this finding does not answer the question of the size and scope of the Iraqi program in biological weapons, since the evidence has almost certainly been hidden or may have been destroyed in the period immediately after the ground war). Interviews with senior Iraqi officers after the war confirmed that neither chemical nor biological weapons were used, or deployed in anticipation of use. It thus appears that Iraqi forces made the strategic decision not to deploy or use biological weapons in the Gulf war.

2. Chemical Agents

Attention has also focused on chemical weapons, and the possibility that troops were targeted by these weapons, or were exposed to low levels of chemical warfare agents. It is important to recognize that the nature of an attack with chemical weapons is to produce a localized concentration of chemical warfare agent that is sufficient to kill or incapacitate unprotected personnel in the immediate area of attack. The cloud of chemical warfare agent vapor resulting from an attack is dispersed through diffusion into the atmosphere both horizontally and vertically. The rate of this process of dispersion is determined by the nature of the local meteorological conditions. During conditions of atmospheric stability, the cloud can present a hazard for a kilometer or so downwind of the point of attack but this distance is significantly reduced under unstable atmospheric conditions that prevail for most daytime hours in the Gulf. As a result, the concentration of chemical warfare agents in the air is reduced to an insignificant level very rapidly as a function of distance and time. So far as has been currently determined, there was no use of chemical weapons during the war. Any exposure would have had to resulted from accidental release following bombing of storage bunkers or deployment sites.

Table 16

Chemical Agent Effects

3. Evidence for the Presence of Chemical Agents in the Gulf Theater

Iraq possessed large stores of chemical weapons, and deployed them to rear storage areas, with the closest of those to U.S. forces located northeast of Kuwait, about 150 km from the Saudi border. Information on the location and conformation of these storage areas was derived from analysis of intelligence information before and during the war, and from on-site examination of them after the war. Iraq is believed to be the only nation that had chemical weapons in the Gulf theater.

During and immediately after cessation of the active campaign, coalition forces examined all the forward bunkers within the occupied portion of Iraq, essentially south from the Euphrates River. These were the bunkers that housed Iraqi troops, conventional munitions, and other stores of supplies; if chemical munitions had been deployed forward, it is likely they would have been present when the ground war occurred, and overrun by coalition forces. No quantities of chemical munitions of any type were found. There were also no Iraqi chemical mines encountered, either during the hostilities or during the extensive postwar cleanup. The fact that no chemical munitions have been discovered is the most compelling evidence that, for whatever reason, Iraq did not have chemical weapons deployed to forward positions in preparation for use at the time of the land war. Chemical weapons were present in rear storage areas nearer the production facilities.

The conclusion that there were not chemical weapons directly in the war zone is compatible with other, more indirect, evidence from interviews of Iraqi troops although this source must, for obvious reasons, be considered uncertain in their reliability and their relevance to the entire period of U.S. presence in northern Saudi Arabia preceding the land war. The subsequent Iraqi declarations to the UN inspection teams after the land war had ended also did not indicate that there were chemical weapons directly in the war zone.

A number of pieces of information--satellite photographs, other intelligence information, on-site ground assessment by U.S. forces during and at the conclusion of the land war, and inspection by UN teams that included US personnel--located the area in which chemical weapons may have been stored closest to coalition forces as being in the general vicinity of An Nasiriyah. (3058N:04611E) Some of the bunkers in this general area were identified as possibly containing chemical or biological munitions, primarily on the basis of their characteristic structure. Bunkers in a storage area at An Nasiriyah were first targeted on January 17, the first day of the air war (and later, on January 30 and February 1); those at Talil airbase on February 19. These bunkers suffered varying degrees of damage, confirmed by aerial imagery. There were also reports of damage by the United Nations Special Commission inspection team that visited a different location in the general vicinity of An Nasiriyah several months after the cessation of hostilities. There are indications that the site visited by the UNSCOM team was not a site targeted during the air war but may have been specially constructed for the UN inspectors.

It is unclear what quantities, if any, and types of chemical warfare agent may have been released during these attacks. Detailed assessment of damage was difficult. It is, however, relevant that when the bombs penetrated the bunkers and exploded, they often did not produce massive explosions that could have scattered and disrupted the contents of the bunker. Rather, photo reconnaissance indicated that damage ranged from a single hole in the bunker (from bomb entry) with no other apparent damage, to major structural damage with the roof slab broken in several places and collapsed.

Release of chemical agents from these damaged bunkers would have resulted from damage to the munitions in the bunkers and then escape of the chemical agents as vapors. It is difficult to model the disruption of munitions in bunkers, but given the relatively low vapor pressures of the agents, the uncertainties in the extent of damage inside the bunkers, and the apparent absence of factors that might have accelerated the escape of the chemicals (such as large secondary explosions or fires that would have destroyed the chemical agents which are organic compounds), escape of agents would have occurred slowly (if at all) over an interval of time (probably days to weeks) rather than as a point event.

There are three sites that may have stored chemical munitions in the vicinity of An Nasiriyah. The indication is that UN inspectors were taken to a separate site that was not bombed.

An Nasiriyah. The extent of damage to An Nasiriyah, and when it actually occurred, due to the bombing is not completely clear: imagery shows only one of the possible CBW bunkers was hit on the January 17, with minor damage. Eventually all the bunkers were destroyed, but it is unclear whether any contained chemical munitions.

The storage facility near the airbase at Talil. Talil was a major airbase, and associated with it was an extensive complex of bunkers for the storage of supplies and munitions. Reconnaissance identified several bunkers as possible sites for storage of chemical and biological weapons, based on observations of the use of bunkers with similar characteristics during the war with Iran. At least some of these bunkers were hit during the air bombardment. If any chemical munitions were stored in these bunkers, any release of chemical agents was not relevant to the reported responses of the Czech detectors, as the bombing of the Talil bunkers occurred much later in the war.

The site visited by the UN inspection team. Several months after the end of the war, a UN inspection team visited a site in the general area of An Nasiriyah. It appeared this was a separate site constructed by Iraq after the war to show to the UN inspectors. The Iraqis claimed that munitions containing 16 tons of Sarin were destroyed in the bombing (a number in agreement with the complete destruction of the rockets in the bunker). There was also some indication that the munitions were only destroyed subsequent to the ground war by the Iraqis. The uncertainty stems from the fact that it is not clear whether the site the UN inspection team was shown was in fact this subject of bomb damage.

Probably the most compelling evidence against a large release of chemical agents from these sites is the absence of any reports of casualties among Iraqi personnel, or at other Iraqi chemical weapons sites that were attacked during the air war. Neither reconnaissance evidence nor interviews with Iraqis after the war indicated that there had been casualties from escape of chemical agents from bunkers damaged at these sites. Examination of the damage around Muthanna (the central Iraqi chemical weapons production facility) after the war, and interviews with local personnel, also indicated that there were not extensive local casualties following damage to this site. This evidence that venting of chemical agents from damaged bunkers was at a low level, even locally, is important. For there to have been significant exposure to U.S. forces located approximately 200 km from An Nasiriyah, there would have been a very large release at the source. There is no evidence that such a point release occurred.

What level of exposure would have been detected locally? Sensitivities and Detector Networks.

During the period from the beginning of the air war to the end of the ground war, there were a number of alarms from U.S. chemical agent detectors. (Appendix B contains a timeline that highlights some of these) None of these alarms were confirmed as valid: all were concluded to be false alarms. This conclusion was also reached by other nations in the coalition forces.

There were, however, a small number of events that might, somewhat ambiguously, have resulted from the presence of chemical agents--

None of these claims of detection have been confirmed. These events are described below in greater detail. The absence of confirmed detections of chemical agents by U.S. forces lead to the conclusion no exposure to chemical agents by US forces occurred, as any hypothesis that some troops were exposed to levels less than those detectable by US detectors and such that casualties would have been suffered from chemical agents.

Interpreting the conclusion that there was no detectable exposure to chemical agents requires both understanding the structure of the U.S. system for detection of chemical agents, the distribution, reliability and sensitivity of the detectors that form this system, and the protocols followed in the use of the system. U.S. forces are equipped at various levels with detectors that serve different purposes, and have inherent sensitivities and specificities.

4. Liquid Chemical Agent Detectors

The most widely available detectors are treated papers (M8 and M9) that are sensitive to droplets of liquid chemical agents. These papers were distributed to individual level, and are worn attached to clothing or equipment (M9), or are used to investigate surfaces suspected of being contaminated (M8). These papers are intended only to provide indication of the presence of a liquid chemical agent hazard, either after receiving a suspected chemical attack, or when entering an area of suspected contamination. They are inexpensive and effective for an individual to determine if there is a liquid chemical agent hazard present, but they are not highly specific for chemical agents. They can respond to other organic substances, such as brake fluid. Users are trained to avoid placing the paper in contact with other substances known to cause false readings, and to consider other possible indicators of chemical agent presence when assessing a positive reaction of the paper.

Table 17

Liquid Chemical Agent Detector Characteristics

* The quantitative units used for each device vary due to method of use and design specification.

A specialized kit that was fielded to units responsible for fresh-water handling, the M272 kit can detect the presence of chemical agents in water. If a supply of water is suspected of being contaminated, because the water source has been in the area of a chemical attack or if it has flowed through an area of contamination, this device would be used to ensure the safety of the drinking water.

The FOX NBC (Nuclear, Biological and Chemical) Reconnaissance System is a wheeled, armored vehicle equipped with an on board mass spectrometer for the identification of chemical contamination. Sixty FOX systems were given to the US by Germany during Desert Shield; 50 went to Army units, and 10 to US Marine Corps forces. The FOX was designed to locate and mark the presence and extent of liquid chemical agent contamination. Two sampling wheels mounted on the rear of the vehicle roll on the ground, and are lifted up and "sniffed" by the sampling probe at intervals. The FOXs, operated by specially trained chemical specialists, were ca]led on, if located nearby, to confirm possible or suspected chemical agent detections.

5. Vapor Chemical Agent Detectors

Table 18

Vapor Chemical Agent Detector Characteristics

The most widely available detector for determining the presence of chemical agent vapors is the M256Al Chemical Agent Detector Kit. These kits contain vials of liquid chemical reagents that are combined and exposed to the air in a specific sequence to indicate the presence of hazardous levels of chemical agent vapors. The kits must be manually manipulated, and the full sequence of tests takes 20-25 minutes; consequently, these are not used for monitoring or warning of personnel. Rather, these devices are used by trained personnel after a unit has entered full protective posture, to determine if a hazard actually exists in the immediate area, and to assist the local commander in initiating un-masking procedures if there is no indication of hazard. These kits are more sensitive for nerve agent than the automatic alarm, and are not sensitive to the same type of interferents that can cause false alarms. Approximately 45,000 of these detector kits (each of which contains 12 actual detector packets) were deployed in the Gulf.

The M8Al Automatic Chemical Agent Alarm electronically monitors for hazardous levels of nerve agent vapor. Once placed into operation, it will run for up to 24 hours before needing servicing. The detector component of this system can be displaced upwind from the unit's position and connected by wire to an audible and visible alarm module. Units use this device when in stationary positions; it cannot generally be operated while on the move. While sensitive, this device is also prone to false positive responses under some conditions due to high concentrations of certain organic compounds (some pesticides, vehicle exhausts, rocket smoke) and troops are trained to use care in emplacing the device to minimize the chance of false alarms.

Although it detects vapors, in actual practice the Chemical Agent Monitor (CAM) serves as a post-attack device for determining the presence of vapors emanating from localized liquid contamination. This hand-held air sampler detects and identifies nerve and blister agent vapors, and depicts in a rough quantitative form on a bar-graph display, the degree of contamination.

Although sensitive and specific for identification of ground contamination, the mass spectrometer system on board the FOX is not optimized for sampling and alerting to generalized airborne vapors of chemical materials. When operating in the air sampling mode, the FOX is not a suitable warning device; very high concentrations of chemical agents would have to be present, such that unprotected troops in the vicinity would be adversely and acutely affected.

The confirmation of the presence of a chemical agent requires examination by a second detector, one using a different principle of operation. For final field verification of the presence of chemical agent, the FOX was the item of choice. In practice, none of the preliminary alerts for possible presence of chemical agents reported or investigated by U.S. forces were confirmed as valid. Consistent with the experience of other coalition partners, this conclusion confirms that there were no exposures at levels high enough to trigger U.S. alarms. It does not, by itself, rule out the possibility of exposures below the threshold of U.S. detectors, although such exposure could not occur without detectors located upwind having positive and confirmed responses and possible physiological signs from chemical agent exposure at these higher levels.

The highest level of chemical agent to which U. S. personnel could have been exposed without triggering an alarm is determined by the threshold sensitivity of the detectors. On the basis of detector specifications, the highest concentration to which U.S. personnel could have been exposed was 0.2 mg/m3 of nerve agent, and 2 mg/m3 of mustard.

Possible Detection Incidents: A Mustard-contaminated Bunker near Basra.

The incident that provides the most probable case of exposure of an American soldier to a chemical agent was an accidental exposure that occurred while inspecting bunkers in southern Iraq after the conclusion of the ground war. The soldier entered a number of bunkers while performing his mission to locate enemy equipment, personnel or intelligence material. Approximately 8 hours later, he experienced skin irritation and reddening. After 8 more hours, he presented to unit medical personnel with erythema and two small (1-2 cm) blisters on one arm consistent with a mustard exposure. A FOX vehicle was called to determine if the soldier's clothing was contaminated; it initially identified EQ mustard. The following day, two FOXs were called in to confirm the reading; of the two FOXs present on this occasion, only one could get a reading, but this time of HD mustard. The FOX teams were not able to find contamination in any of the bunkers entered by the soldier.

Several other scientific findings confound this story, however. When the soldier's clothing was shipped back to the US for subsequent examination under laboratory conditions, no traces of mustard or its highly stable degradation products were found. Additionally, urine samples taken from the soldier were negative for the presence of thiodiglycol, a metabolite typically observed from exposure victims. Nevertheless, based on the symptoms shown by the soldier, and on the positive identification by one FOX, it seems plausible that this soldier was, in fact, exposed to mustard. As an apparently singular event, however, it carries no implication of a mechanism for exposure of a significant number of other U.S. personnel.

Possible Detection Incidents: Czech Announcements of Detection.

The announcement in the summer of 1993, following US media and Congressional interest in whether there were unexplained health effects in Gulf War participants, that Czech chemical detection units had reported that their detectors had responded in three separate incidents during the beginning of the air war, attracted substantial attention. These reports were the only ones that seemed to provide any support to the idea that there might have been any chemical agents in the regions occupied by U.S. forces, and that these agents might have originated in bunkers damaged during the bombings.

Examination of the Czech reports indicates that the accuracy of their detection is still uncertain and that there are a number of internal inconsistencies in the available information. It is not clear that any of the incidents described by the Czechs unambiguously identified chemical agents, and the origin of the materials sampled is even more uncertain.

The important incidents surrounding the Czech detections are listed below in boldface; associated, relevant events are also included in this list. A map of Saudi Arabia at Appendix E.

These incidents can be broken into two sets: the cluster of reports of nerve agents by Czech units in the three days (Jan 18 - Jan 20) following the bombing of An Nasiriyah on Jan 17, and the examination of the puddle of mustard on the 24th The date of another possible release--the bombing of a bunker at Talil--is also included for comparison, although there were no alarms following this event and it occurred much later in the air war.

Czech and French reports in the Interval January 17 - 20. These events were in a time period when it might, in principle, have been possible for them to reflect venting from a bunker or bunkers at An Nasiriyah. Because of the uncertainties in the estimates of damage at An Nasiriyah, it is only possible to provide an upper limit to the possible release of nerve agents. If it is assumed that one bunker was destroyed, that the bunker had contained chemical agents and that an estimate of 16 tons of sarin being contained in a single bunker is correct, then the maximum release of nerve agent that could have occurred on the 17th was 16 tons. In fact, the total amount would have been less, since the venting would occur slowly, and all the chemical agent in the chemical rounds in the bunker would not actually be released.

On January 17 and 18--the days immediately following the bombing of An Nasiriyah--the weather conditions were unfavorable for movement of vented material toward the coalition forces: On the 18th it rained all day, and the wind was from the Southeast (that is, from Saudi Arabia into Iraq). Due to the high solubility of Sarin in water (21 g/L,) rain would have significantly reduced the concentration of Sarin vapor. On the 19th the wind began to shift to the northwest, but there was an occluded front over the region in question. The microclimate was variable, and the Czech report of local winds from the northwest in the wadi in which they were traveling is believable, but probably not relevant to movement of a plume from An Nasiriyah toward U S. forces.

The mustard puddle on January 24. This event occurred too late to be associated with the bombing on the 17th. Saudi personnel directed the Czech unit to a puddle of damp ground in a remote area, and asked them to investigate. The Czechs detected mustard. No effort was made to confirm the identity of the material, nor were soil samples taken for laboratory confirmation. This peculiar event may have been some type of test or training exercise by the Saudis, although no confirmation of this hypothesis has been received from them.

Other Incidents.

There were a number of other observations and events reported as evidence of use of chemical weapons. Appendix B lists a number of these. Here we describe four, with the purpose of showing how combinations of anxiety, inexperience with equipment or unfamiliarity with the local environment generated confusion about the presence of chemical weapons

Event near Al Jubayl. On January 20, members of 24th Naval Reserve Construction Battalion (Seabees) were awakened from sleep by a loud noise. They moved to bunkers and donned protective masks. Tests for chemical agents were negative. Recent reports by members of this group, describing a strong ammonia smell and burning skin was not corroborated by log entries. An adjacent unit described a sonic boom at roughly the same time, but no other unusual events.

"Purple Tee-Shirts". Members of the same Seabee unit reported an event in which a distant noise, a "mist" and a smell of ammonia were accompanied, subsequently, by sections (especially in the area of the armpits) of the brown tee-shirts worn by some personnel turning purple. There were no symptoms of chemical toxicity. This configuration of events was interpreted by some of those involved as evidence of attack by a rocket with a chemical warhead. There was no evidence to support this interpretation.

An analysis of dye chemistry, and of several tee-shirt samples obtained from the unit, conducted by the Natick Research, Development and Engineering Center concluded that the probable cause of the color change was exposure to nitric or nitrous oxide fumes.[3] These materials may have been present in the industrial area in which the Navy unit was billeted. Tests using a wide range of industrial acids, bases and oxidizers were used to determine dye reaction; it is interesting to note that exposure to ammonia did not elicit a color change. Past records from agent challenge tests to clothing materials, conducted at Dugway Proving Ground, indicate no color change associated with any chemical agent test.

Although the details of the events contributing to the incident are still not clear, it is probable that exposure to a release of some industrial chemical or to perspiration (or some combination of these factors) was the factor underlying the color changes.

"Lewisite Detection". On February 26, during the ground war, a FOX operated by Marines operating along the Saudi Arabia/Kuwait border alerted to Lewisite; reexamination with the M256Al kit failed to confirm this detection. Lewisite was not in the Iraqi inventory. The mass spectrometer on the FOX operates by drawing a sample from the exterior through a silicone membrane into the inlet of the mass spectrometer. The FOX involved in this incident was operating with a new membrane, and with a crew that had only recently completed training. The mass spectrometric signature of Lewisite is similar to that of silicone plasticizers used in the membrane. This incident thus probably reflects a misinterpretation of a confusing signal, resulting from the leakage of silicone plasticizer from the new membrane.

"Dead Animals along the Road." U.S. forces noted the presence of numbers of dead animals along the sides of the roads in certain areas, and were concerned that these animals had died by exposure to chemical or biological agents. The animals were certainly present, but the interpretation of their presence requires an understanding of the Saudi Arabian agricultural system. When valuable domesticated animals--sheep, goats, camels--die in Saudi Arabia, the carcass is moved to a nearby road. Collecting the remains along the roads has two purposes: to allow the local administrators to verify the deaths (in order to compensate the owner for the losses), and, in some cases, to help the local agricultural officers or veterinary personnel to inspect or sample the carcasses to help establish the cause of death. No information was presented that would indicate that the circumstances surrounding the dead animals were related to chemical or biological agents.

Could Chemical Agents Released on Bombing the Storage Sites in the Vicinity of An Nasiriyah Have Exposed U.S. Forces?

Since these sites were suspected at the time to have chemical weapons, and since they were the closest such sites to U.S. and coalition forces, the circumstances surrounding their bombing has been examined to detail to see if they could be the source of the chemical agents detected by the Czech units, or if there might otherwise plausibly be a source of low-level exposure of U.S. personnel.

Modeling performed by the Defense Nuclear Agency using the ANBACIS (Automated Nuclear, Biological and Chemical Information System) II computer program demonstrates that the maximum extent to which a lethal concentration (LCt 50: lethal to 50% of exposed personnel) would travel would be 8.7 km. Incapacitating effects would be expected out to 9.3 km. Similar examinations of the other southernmost suspected chemical storage bunkers resulted in similar hazard distances. No cases resulted in any hazard areas coming within 150 km of any US or other coalition forces. These estimates are very similar to the results of an unpublished CBDE Porton Down Report dated September 1992, which detailed UK studies on the potential effects of bombing Iraqi CBW production and storage sites.

Several lines of evidence indicate that it is improbable that any release of chemical warfare agents at An Nasiriyah is connected to Czech detections (with the obvious further caution that the Czech detections themselves remain suspect, pending checks on the performance of their equipment and resolution of inconsistencies in accounts by Czech personal of equipment and procedures).

Extent of Damage at An Nasiriyah. If chemical munitions were stored at An Nasiriyah and if a bunker containing chemical munitions was hit, then a plausible upper limit to the amount of nerve agent in such a bunker would be 16 tons; in practice, the amount released would be much less. Plausible amounts of vented material are too low to have traveled the 150 - 200 km to the Czech units in detectable concentrations.

Apparent Absence of Other Casualties in the Vicinity of An Nasiriyah. To have a detectable amount of nerve agent in Saudi Arabia, there would have had to have been a large release in An Nasiriyah. A large release should have produced local casualties. None apparently occurred. The inference that any release was small, even at the source, is confirmed by observations after a later bombing at Talil, and by bombings at Muthanna.

Weather. The weather was unfavorable for movement of nerve agent toward coalition forces: the wind measured at Hafir al Batin between the 17th and the l9th was from the south-southwest, then southeast on the 17th; from the east-southeast on the 18th with rain; from the east-southeast in the morning of the l9th, changing to from the north-northeast with the passage of a weather front.

Plume Analysis. Mathematical modeling of the plume from a release suggests that a larger quantity than could have plausibly been released would have been required to reach the Czech forces in detectable amounts. The task force was briefed that under best case weather conditions, 80-100 tons of agent instantaneously released could have resulted in the concentrations described by the Czechs.[4]

The conclusion from these considerations is that it is very unlikely that the Czech units detected nerve agent released on bombing An Nasiriyah.

This same analysis shows that, regardless of the truth of the Czech reports, bombing the sites around An Nasiriyah was not likely to be a more general source of significant exposure of U.S. forces. If the Czech detections were correct, and if they were detecting chemicals vented from An Nasiriyah (both substantial "ifs"), the plume would have had to be relatively sharply defined (another conclusion that is difficult to believe, given the variability of the wind direction and the weather in this period). A sharply defined plume that coincidentally reached the Czech units would not have covered a significant area of the front, and would not have exposed many U.S. personnel.

More Distant Storage Sites. Chemical weapons were also present at several sites in central Iraq (Al Habbaniyah, Karbala, Samarra). In the period leading up to Desert Storm, some chemical munitions were dispersed from the manufacturing and filling site at Muthanna to these storage sites. The distances of these other sites from the area of operations in the theater precludes them as a source of chemical exposure to U.S. forces. Dilution in the air of agents released in bombing the sites, and the effects of atmospheric turbulence and rain make it impossible for these more distant sites to have acted as significant sources of exposure.

Conclusions. The conclusion from this analysis is that U.S. personnel were not exposed to any significant levels of chemical or biological agents during the Gulf war. A summary of the evidence and inferences follow: