Some Gulf War veterans have reported incidents involving encounters with, or observations of colored clouds and mist during and immediately after the war. These clouds or mists were described as having strong odors, causing an immediate burning sensation to the eyes, skin, nose, and throat; they also caused respiratory irritation, nausea, and vomiting. Some veterans have speculated that these symptoms were caused by exposure to chemical warfare agents following a Scud missile interception or impact during Operation Desert Storm.  Investigations to date have found no evidence that Iraqi Scuds carried chemical warfare agents during the Gulf War and no evidence that US servicemembers were exposed to chemical warfare agents from Scud attacks. The veterans who have suggested chemical warfare agent exposure may actually have been exposed to weapon-system components and industrial chemicals, such as liquid rocket fuel and oxidizers.

Inhibited red fuming nitric acid is such an oxidizer and contains mostly nitric acid, nitrogen oxides, a small percentage of water, and an inhibitor (an additive which prevents the acid from eating through its metal storage tank). This inhibitor is a halogen substance, such as hydrogen fluoride or iodine.

When combined under controlled conditions with rocket fuel, inhibited red fuming nitric acid combusts to create the thrust needed to launch a rocket or missile. During the Gulf War, the Iraqi military used inhibited red fuming nitric acid as the oxidizer in several weapon systems, including the Scud, Guideline, Silkworm, and Kyle missiles. These weapon systems were located and used throughout the Kuwaiti theater of operation.

There were four major ways in which servicemembers might have encountered fumes, vapor, or residue from missile fuels and oxidizers on the battlefield:

Nitric acid exposure causes the corrosion of skin and body tissue on contact with the liquid and lung injury after inhalation of the vapor and/or decomposition products of the nitrogen oxides. The greater danger is lung injury from breathing the highly toxic nitrogen oxides, particularly nitrogen dioxide. This injury can lead to the delayed development of pulmonary edema (fluid build-up in the lungs, resulting in a lack of oxygen). These pulmonary effects generally occur only following an acute encounter (after inhaling a high concentration of nitrogen dioxide, for instance) in an enclosed space (like a vehicle compartment or enclosed small room). There are no known incidents during the Gulf War in which exposure to inhibited red fuming nitric acid resulted in pulmonary edema.

During the Gulf War, protective measures against inhibited red fuming nitric acid were used. The most effective measures included: avoiding impact sites and not handling missile fragments; taking cover or finding shelter during missile overflights; and wearing proper protective equipment to prevent inhalation and exposure to the skin when disassembling or working around broken-up or live weapon systems.

Army LANCE units had detection devices to monitor the level of inhibited red fuming nitric acid from their own weapon systems; however, these units were not deployed to the theater.  In effect, US forces in the Gulf had no equipment to detect the presence of inhibited red fuming nitric acid. The available chemical warfare agent detection equipment was not designed to detect inhibited red fuming nitric acid. When the M256A1 Chemical Agent Detector Kit was tested with laboratory-grade red fuming nitric acid (without an inhibitor) at the Edgewood Research, Development and Engineering Center, the detector kit readings falsely indicated the presence of the chemical warfare agent hydrocyanic acid (hydrogen cyanide, a blood chemical warfare agent).

This paper covers the following:

The paper concludes with lessons learned and suggests measures that the Department of Defense might use in the future to ensure force protection against the hazards of substances such as inhibited red fuming nitric acid. These lessons learned and suggestions include improvements in:


A number of reports already published by the Office of the Special Assistant have addressed the use of inhibited red fuming nitric acid during the Gulf War. These reports include the Kuwaiti Girls’ School and Al Jubayl case narratives, and information papers on such topics as the M8A1 Automatic Chemical Agent Alarm System (M8A1) and the Fox NBC Reconnaissance Vehicle. Current research efforts involving the use of inhibited red fuming nitric acid include future information papers on such topics as the Scud missile and the M256 Chemical Agent Detector Kit.

Inhibited red fuming nitric acid is a highly corrosive oxidizing agent in liquid rocket fuel which is combined with a kerosene mixture in Russian-made missile systems like the Scud.[2] Inhibited red fuming nitric acid contains nitric acid, nitrogen oxides, a small percentage of water, and less than one percent of a special additive, called an inhibitor.[3] This inhibitor, which can be hydrogen fluoride or some other halogen such as hydrogen iodine, prevents the highly corrosive nitric acid from eating through its metal storage tank.[4][5]Inhibited red fuming nitric acid ranges in color from colorless to reddish-brown.[6] At high concentrations, inhibited red fuming nitric acid, red fuming nitric acid (usually found only in laboratories or industrial production plants), and nitric acid are all very corrosive and potentially lethal.[7][8]

In this paper, inhibited red fuming nitric acid will be referred to by its abbreviation: IRFNA. At times, specific quotations use the terms "nitric acid" and "red fuming nitric acid" interchangeably. This usage is intended to preserve the integrity of the research and references, rather than to confuse the reader. The contents and hazards of IRFNA and red fuming nitric acid (RFNA, without the inhibitor) are similar.[9][10]

This paper draws upon documented IRFNA exposure experiences, US Army Central Command (ARCENT) logs, and Gulf War veterans’ reports consistent with possible IRFNA exposure. Some of these veterans’ reports have appeared in congressional testimony.[11] Other veterans have chosen to report their observations and incidents directly to the Office of the Special Assistant for Gulf War Illnesses. This paper is not a comprehensive study of veterans’ reports, illness symptoms, or Scud (or other missile-systems) locations and use. Rather, this information paper is part of an effort to inform veterans and the public about the technical characteristics of one toxic substance present on the battlefield during and after the Gulf War.

Some Gulf War veterans suffering from illnesses have reported incidents involving yellow, brown, or red-colored clouds, yellow mist, and strong odors. Reported short-term exposure symptoms included a burning sensation in the eyes and on exposed skin, irritation in the throat and respiratory system, nausea, and vomiting. Some veterans have speculated that these clouds and mists contained chemical warfare agents. These veterans believe that their symptoms were caused by exposure to these agents following a Scud intercept or impact during the Gulf War. However, the evidence found to-date indicates that no Scud carried chemical or biological warfare agents during the Gulf War.  Industrial chemicals and weapon-system components, such as fuels and oxidizers, may have been part of the clouds witnessed by veterans. To-date, IRFNA is the only such weapon-system component studied.

As early as July 1995, the Central Intelligence Agency (CIA) had completed a study of Scud impacts and veterans’ reports. The CIA found that, "… while some accounts which cite Scud missiles are probably related to something else, other accounts are accurate and some veterans were probably exposed to Red Fuming Nitric Acid (RFNA)…."[12] In an August 1996 report, the CIA concluded that, "Although we know of no long-term illnesses related to these chemicals, we assess that RFNA is a likely cause of some burning sensations reported by veterans near Scud impacts."[13]

The Department of Defense Persian Gulf War Veterans’ Illnesses Investigation Team, the predecessor to the Office of the Special Assistant for Gulf War Illnesses, reported to the Presidential Advisory Committee on Gulf War Veterans’ Illnesses that residual RFNA could have escaped from a launched Scud missile, especially if the missile did not fully detonate, causing a vapor hazard. The team also reported that

When released, RFNA is a reddish brown cloud.… It is an irritant to the skin, mucous membranes, eyes and respiratory system. Acute exposure symptoms, which may be delayed up to as much as 30 hours, include dizziness, headache, nausea, general weakness, chest tightness, and difficulty breathing. In some reported incidents … acute symptoms similar to those experienced with RFNA exposure were associated with reported SCUD attacks.[14]

While the possibility exists that IRFNA caused the reported symptoms, troops observing these clouds and symptoms were not equipped with monitoring devices designed to detect the presence of IRFNA. They had no way to determine whether these exposures involved IRFNA. The chemical warfare agent equipment used by servicemembers in the Gulf War was designed to detect very specific chemical warfare agents.

In January 1997, the Office of the Special Assistant for Gulf War Illnesses began its investigation into the hazards associated with the Scud missile and its fuel. On a liaison and research trip to the Middle East in the fall of 1997, investigators from the Office of the Special Assistant gathered information regarding the Israeli Scud Recovery Unit’s experience with Iraqi Scud missiles during the Gulf War. The Scud Recovery Unit confirmed prior reports that "… in-air hits destroyed the Scuds’ booster rocket, not the warhead."[15] Because every warhead recovered by the Israeli Scud Recovery Unit was conventional, the colored mist or clouds seen after the intercept of some Scuds could not be attributed to the presence of chemical or biological warfare components. The director of the Israeli Scud Recovery Unit reported that generally when a Scud was shot down, "a yellow cloud of mist was produced by the release of red fuming nitric acid.… People exposed to the mist at the time of impact did experience burning sensations on their exposed skin."[16]


A.  Basic Properties of IRFNA and Rocket Fuel

The combination of rocket fuel and rocket fuel oxidizer is called rocket propellant.[17] When combined under controlled conditions with a fuel, such as kerosene or unsymmetrical dimethylhydrazine (UDMH), the oxidizer causes the fuel to burn and to create the thrust needed to propel or launch a rocket or missile.

During the Gulf War, Iraq used IRFNA as the oxidizer in several missiles discussed later in this paper. Iraq stored IRFNA in aluminum or stainless steel tanks—like the one in Figure 1, which was found in 1991 at the Al Badawiyah Girls’ Sciences School (also known as the Kuwaiti Girls’ School) in Kuwait City.[18] IRFNA also has been used as a decontamination substance in facilities producing mustard agent.[19] Whether Iraq used IRFNA as a decontaminant in its mustard agent production facilities is unknown.

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Figure 1.  Stainless steel storage tank with IRFNA venting through a bullet hole

B.  Iraqi Missile Fuels

In addition to IRFNA, missile fuels were also potential battlefield hazards to Coalition forces. The missile fuel that Iraq used in its older Soviet systems was a specially refined kerosene-like substance (called kerosene in the literature).[20] Some improved missiles used UDMH in combination with IRFNA. The Soviet Union used UDMH in their Scuds,[21] but we have no evidence that Iraq used UDMH.

C. Iraqi Weapon Systems Known to Use IRFNA

Coalition forces knew of at least four Iraqi weapon systems that used IRFNA in the Gulf War: the Scud, Guideline, Silkworm, and Kyle missiles. A brief description of each weapon system follows.

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