The fire service has long been aware that hydrogen cyanide is one of the many products of combustion to which firefighters are potentially exposed. What the Providence (RI) Fire Department learned in March 2006 was that not only is hydrogen cyanide a product of combustion but it may also very well be the most deadly product of combustion and the one firefighters should be concerned with above all others when fighting fires.

Is this news? Is cyanide more of a problem than carbon monoxide? If cyanide poisoning among firefighters were really such a huge problem, why wasn’t it discovered long before this?

On March 23, 2006, after a fire in a fast-food restaurant at 1197 Broad Street, a Providence firefighter began experiencing symptoms that included headache, weakness, fatigue, shortness of breath, and a cough. After the fire, while cleaning up back at the station, several other firefighters observed that the member was talking incoherently.

The member was reluctant to seek medical attention but eventually was transported to Rhode Island Hospital, a Level I trauma center and teaching hospital affiliated with Brown University Medical School. While he was being treated in the emergency room for smoke inhalation, Dr. Kenneth Williams, MD, FACEP, an associate professor at Brown Medical School, happened to walk past. On seeing the member’s condition, Dr. Williams instructed the attending physicians to test for cyanide poisoning in addition to carbon monoxide. When the results came back, they showed that the member indeed had toxic levels of cyanide in his blood. He was then given a cyanide antidote.

On learning of the cyanide poisoning, the initial belief among our department members was that the firefighter’s condition was an isolated and highly unusual case. As a precaution, all members who operated at 1197 Broad Street and experienced any symptoms associated with cyanide poisoning were instructed to go to Rhode Island Hospital to have their blood tested. Sixteen members went for testing, and three additional members were found to have toxic levels of cyanide. The assumption among firefighters then became that there was something unusual about the Broad Street fire that led to the cyanide poisonings.

After two more fires over the next 14 hours resulted in four more members being found to have toxic levels of cyanide, including one who suffered a heart attack, the magnitude of what had happened began to dawn on firefighters and doctors alike.

After a thorough investigation into what occurred in Providence, it appears that cyanide poisoning is neither unusual nor uncommon among firefighters. In fact, research increasingly is pointing to the fact that hydrogen cyanide commonly is present in high quantities at fires. Cyanide poisoning may be responsible for a variety of symptoms and medical problems commonly experienced by firefighters.

How did this go unnoticed for so long? Why is it becoming an issue now? To understand the answers to these questions, we need to look at two entirely different pieces of a complex puzzle. The first involves understanding cyanide and how it comes to be found in fire smoke. The second involves the medical aspects of cyanide and how we measure cyanide poisoning.


Cyanides are a group of chemical compounds that contain an atom of carbon triple bonded to an atom of nitrogen. Some cyanides are manmade; others occur naturally. Cyanides may be solids, liquids, or gases. They are present in the environment around us at all times in small quantities. They may be found in the water we drink, the air we breathe, and the foods we eat.

A cyanide molecule has a strong tendency to bind with other atoms or compounds, yielding a variety of different products. The type of atom or compound to which the cyanide molecule bonds determines the properties and toxicity of the resulting product. Examples of the various types of cyanide include hydrogen cyanide (HCN-cyanide bonded to hydrogen), thiocyanates (cyanides with a sulfur molecule attached), sodium cyanide (NaCN), and potassium cyanide (KCN), to name a few.

The ingredients of cyanide, carbon, and nitrogen are abundantly present around us. Most combustible fuels contain carbon, and the atmosphere is 79 percent nitrogen. However, carbon and nitrogen cannot combine under fire conditions to form cyanide. Combustion does not provide the proper conditions for the triple bond between carbon and nitrogen to form. Rather, any cyanide generated from a fire must have come from the release of cyanide already present in the fuel. Once formed, the triple bond between the carbon atom and the nitrogen atom is quite stable and unlikely to break during combustion of a cyanide-containing fuel.

Cyanide is present in wood, paper, wool, and other natural products in varying levels. However, modern materials such as plastics, polyurethane, various types of foam, synthetic fibers, and pesticides contain significantly higher quantities of cyanide than equivalent amounts of wood, paper, or wool. Cyanide is used in a number of manufacturing processes, including electroplating, pharmaceutical, cosmetic, computer electronics, photographic developing, and metallurgy. It is found in more than 2,650 plant species, including many fruits, nuts, and beans. Not all cyanide-containing substances are harmful. For example, Vitamin B-12 contains cyanide, and it is essential to our health.


Hydrogen cyanide is colorless or pale blue liquid or gas with a faint bitter almond odor. It has an immediately dangerous to life and health (IDLH) level of 50 ppm, a vapor density of 0.94, a flashpoint of 0oF, and a flammable range of between 5.6 and 40 percent. When released into the environment, hydrogen cyanide dissipates, but it may remain in the environment for years. Because hydrogen cyanide is so lethal, it has been used as a chemical agent in gas chambers and as a chemical warfare agent. Concerns also exist about the use of hydrogen cyanide by terrorists.

Hydrogen cyanide is generated when a fuel that contains cyanide burns. The amount of hydrogen cyanide generated in a fire depends on a number of factors including the amount of cyanide in the material burning, the chemical composition of the material burning, the oxygen content in the room, and the temperature of the fire.


Modern materials such as plastics, nitriles, polyacrylonitriles, rubber, polyurethane, and asphalt all contain significant quantities of cyanide and are known to yield large quantities of hydrogen cyanide as they burn. The prevalence of such materials throughout our homes and businesses results in a much higher likelihood that today’s firefighters will be exposed to cyanide in fire smoke than ever before.

Little is known about how hydrogen cyanide travels through fire smoke. Most of the research that has been done to date focuses on measuring the presence of cyanide in fire smoke, not on determining if cyanide remains in the visible smoke or even if it remains localized around the burning item that is off-gassing the cyanide. Some authorities believe hydrogen cyanide is most likely to be present during the free-burning phase of a fire; others suggest it is a bigger problem during overhaul.

In her book In the Mouth of the Dragon: Toxic Fires in the Age of Plastics, Dr. Deborah Wallace discusses the fact that plastics can off-gas hydrogen cyanide at temperatures considerably lower than their ignition temperature through a process known as “quantitative decomposition.”1 As a result of quantitative decomposition, hydrogen cyanide may occur outside the area firefighters normally associate with fire smoke.


A recent research article published in March 2006 by Marc Eckstein, MD, and Paul M. Maniscalco looked at several major fires in which cyanide was found to be the leading cause of death.2

The first incident cited was a prison fire in Argentina where 35 inmates died from the smoke produced by burning polyurethane mattresses. The evidence indicated that inmates were exposed to smoke only for three to five minutes and none had lethal levels of carbon monoxide. However, more than 90 percent of the dead inmates had lethal levels of cyanide.

The second incident was an aircraft fire in Manchester, England, that killed 54 people, all of whom were found to have toxic to lethal levels of cyanide and nontoxic levels of carbon monoxide.

The third incident was the Happy Land Social Club fire in New York, where nearly 90 percent of the 87 fatalities were found to have toxic to lethal levels of cyanide. A high proportion of the victims of the Happy Land Social Club fire had high levels of carbon monoxide as well.

Eckstein and Maniscalco also discussed a comprehensive study conducted by the Paris Fire Brigade in1988-1989 that concluded that cyanide levels were a better predictor of lethality in smoke inhalation victims than carbon monoxide. The Paris Fire Brigade now treats smoke inhalation victims with a cyanide antidote, hydroxocobalamin, in the street, with remarkable results.


Cyanide is a potent poison with a complex mechanism for causing injury. It inhibits aerobic respiration at the sub-cellular (mitochondria) level. Cyanide interferes with an important enzyme in the aerobic pathway, cytochrome c oxidase. In sufficient quantities cyanide will shut down the aerobic pathway, leaving cells to rely solely on less efficient anaerobic respiration. Anaerobic respiration results in a buildup of lactic acid and other toxic substances in tissues and organs. This anaerobic pathway soon becomes incapable of providing the energy the body cells need to sustain life, and cellular damage or death occurs.

Cyanide can also bind with hemoglobin, which in turn reduces the oxygen-carrying capacity of the blood. In addition, cyanide can inhibit approximately 40 other enzymes, which contribute to its toxicity. Some have theorized that cyanide may work synergistically with other fire gases, such as carbon monoxide, to incapacitate and suffocate those exposed to fire smoke. Research in this area is ongoing.

Organs that are heavily dependent on oxygen are particularly susceptible to cyanide poisoning. These organs include the heart, brain, and central nervous system.

Symptoms of acute cyanide poisoning include rapid pulse, difficulty in breathing, general weakness, headache, excitement, giddiness, vertigo, and confusion.3 As the exposure continues signs of cyanide toxicity may be nausea, hypotension, tremors, cardiac arrhythmias, coma, and noncardiac pulmonary edema.4

The signs and symptoms of cyanide poisoning resemble those of carbon monoxide poisoning and oxygen deprivation, leading to difficulties in accurately determining whether smoke inhalation victims are suffering from carbon monoxide or cyanide in the absence of blood tests. (2)


A variety of blood tests can be performed for cyanide, including whole blood cyanide, plasma cyanide, and serum cyanide. What all of these tests have in common is the length of time it takes to analyze the blood sample. The fastest cyanide test available is a complex test that takes approximately two hours to complete. Other cyanide tests take up to five days to complete. Obviously, a test that takes two hours to process has limited usefulness when a physician is treating a suspected case of cyanide poisoning. Doctors treating a critically ill patient cannot wait for two hours to determine a course of treatment. To compound the matter even further, the presently available cyanide antidote can be lethal if improperly administered to a patient suffering from carbon monoxide poisoning and not cyanide poisoning.

Furthermore, most hospitals do not perform blood cyanide tests in-house; they must send the cyanide samples out for analysis. According to information obtained during the Providence cyanide investigation, Rhode Island Hospital was the only hospital in New England that performed cyanide testing in-house and is one of only eight laboratories in the country that perform such tests. Tests that must be sent out may take anywhere from one day to one week to come back. What diagnostic value does a test that takes one day or one week to come back have for a doctor trying to treat a critically ill patient? The apparent result is that emergency room doctors do not regularly test smoke-inhalation victims for cyanide. In the absence of this information, we do not have a good picture of the role that cyanide is playing in smoke-inhalation cases for firefighters or civilians.


Whole-blood cyanide may be measured in grams per liter, milligrams per liter, milligrams per milliliter, micrograms per milliliter, micrograms per 100 milliliters, micrograms per deciliter, and moles. For the sanity of all concerned, the microgram per deciliter (mcg/dL) scale will be used as the scale of reference in this article.

Not surprisingly, not all experts agree on the interpretation of the results of whole-blood cyanide levels. As a general rule, 0 to 20 mcg/dL of cyanide in whole blood is considered normal. Some authorities consider anything above 20 mcg/dL to be toxic; others claim that anything over 50 mcg/dL is toxic. Most authorities agree that levels between 250 mcg/dL and 300 mcg/dL are lethal, although there have been cases where victims have died with levels as low as 100 mcg/dL.


The complexity of the cyanide problem becomes even more apparent when it comes to interpreting the results of the blood tests. Cyanide has a half-life of approximately one hour in the blood. Thus, if a firefighter has a whole-blood cyanide level of 100 mcg/dL immediately after exiting a fire building, the level will be 50 mcg/dL one hour later, 25 mcg/dL two hours later, and 12.5 mcg/dL three hours later. A relatively brief delay in a member’s testing will result in the test’s underestimating the member’s peak exposure level. A delay of an hour to two hours between the exposure and drawing of the blood for testing can result in the cyanide levels’ returning to normal in firefighters who had elevated cyanide levels immediately after the fire.


When a person takes a breath, 58 percent of any hydrogen cyanide in the inhaled air will rapidly be absorbed into the body. In a matter of seconds, hydrogen cyanide will enter the bloodstream, and the body will begin a complex process of attempting to detoxify the cyanide before it can cause damage. The main pathway for detoxification involves the cyanide molecule’s binding to thiosulfate, creating thiocyanate. Once the cyanide is bound as thiocyanate, it is no longer toxic and cannot interfere with aerobic respiration.

Approximately 80 percent of the cyanide that gets into a person’s blood stream will be detoxified by thiocyanate, which eventually is excreted in urine. However, the half-life of thiocyanate in the body is 30 hours compared with a one hour half-life for cyanide.

Another mechanism for detoxification of cyanide involves the binding of cyanide to methemoglobin. Cyanide bound to methemoglobin is nontoxic and eventually will be excreted through the thiocyanate pathway. Several other detoxification pathways also exist.

Unfortunately, the whole-blood cyanide test does not differentiate between the toxic forms of cyanide in the blood and some of the detoxified forms of cyanide such as thiocyanate or cyanomethemoglobin. The result is that firefighters exposed to cyanide at a fire may test high for cyanide many hours after an exposure even though the level of toxic cyanide has decreased. In Providence, one member was found to have a whole-blood cyanide level of 72 mcg/dL some 27 hours after a fire. The member was highly symptomatic after the fire and probably had a very high level of cyanide in his body at one time. However, over the course of the 27 hours, much of the cyanide was converted to thiocyanate or methemoglobin, resulting in the high readings without toxicity. Doctors are trained to consider a patient’s lactic acid level in conjunction with cyanide to make a proper evaluation.5


When you consider the complexity of the cyanide issue-cyanide’s short half-life, the length of time it takes for the cyanide test to be performed, the few laboratories that do cyanide testing, and the difficulty in understanding the test results-it is no wonder that the pieces to this puzzle have not been assembled. Had Dr. Williams not ordered the cyanide test on one of our firefighters on March 23, 2006, and had one of our members not had a heart attack on March 24, 2006, the Providence Fire Department would not have been prompted to investigate this matter fully. Had Rhode Island Hospital not had the capabilities to perform in-house cyanide testing, Dr. Williams may never have ordered the test, or, at best, the test results of the first member would not have been returned until days later. The member suffering from smoke inhalation would have been treated as if he had carbon monoxide poisoning and would have felt better in a few days. The heart attack on March 24, 2006, would have been attributed to the stress of fighting the fire, and no one would have made the connection between cyanide and fire smoke.


On March 24, 2006, one of our firefighters, Kenneth Baker, suffered a heart attack while operating at the scene of a fire. He was promptly attended to by members of the Providence Fire Department. CPR was initiated and advanced life support measures were taken, including intubation, defibrillation, and the administration of intravenous cardiac medications. Ken Baker survived but continues a long road to recovery.

The connection between Baker’s cyanide level and his heart attack are subject to evaluation and debate among doctors and toxicologists, but several very important issues were raised. First, cyanide can cause heart arrhythmias.6 According to Dr. Stephen Borron, a noted expert in the medical toxicology of cyanide, cyanide can cause tachycardia, bradycardia, sinoventricular tachyarrhythmia (SVT), atrioventricular (AV) blocks, ventricular arrhythmias, ischemic ECG changes, and eventual asystole.7 Other experts have concluded that cyanide can cause also atrial fibrillation, ectopic ventricular beats, abnormal QRS complex, and sinus bradycardia.8

Furthermore, researchers Baskan and Brewer have concluded that death from cyanide may be delayed up to eight days after the exposure.9 The National Institutes for Occupational Safety and Health (NIOSH) has recognized that electrocardiogram changes can be observed two to three weeks after a fire-related cyanide exposure.10 Although it may never be possible to prove that a cyanide-related heart arrhythmia led to Baker’s heart attack, one indisputable truth is that Baker had elevated levels of cyanide in his blood at the time he suffered the heart attack.

Second, heart attack deaths account for between 40 and 50 firefighter fatalities each year.11 Fortunately, Baker will not be counted as one of those firefighters for 2006, but he very well could have been had it not been for the outstanding prehospital care he received on the scene from members of the Providence Fire Department and then at the Rhode Island Hospital Trauma Center.

According to the National Fire Protection Association, between 200 and 300 firefighters a year suffer nonfatal heart attacks at fire scenes.12 During the course of the investigation into the cyanide poisonings, the committee members reflected on these numbers repeatedly. The committee wrote in its report:

How many of these 200 to 300 fire-scene heart attacks remain non-fatal due to the outstanding ALS care provided by firefighters and paramedics at fire scenes, combined with outstanding treatment in our nation’s trauma centers? Very few professions operate with ALS units standing by when they work. Had 200 to 300 workplace heart attacks per year been occurring among miners while they are in mines, among commercial fisherman while they are at sea, or timber loggers while in the woods, a significant number of those heart attacks could be expected to be fatal due to the lag time of securing ALS care.

This reality strikes the committee: is the fire service severely under-estimating the gravity of the risk of heart attack by focusing only on fatalities? Could the presence and outstanding ability of these on-scene ALS units be masking a problem that is much more serious than the currently cited statistic of 50 heart-related firefighter fatalities per year would otherwise reflect? And what role does cyanide play in these heart attacks? 13


To many, the simple solution to the cyanide problem is to require members to be more diligent in wearing their SCBA. Some have said it’s time for disciplinary action against those who refuse to comply with mandatory mask regulations. However, when you consider all of the issues associated with cyanide, together with the complexity of effectively managing the air supply of all responding personnel, it becomes apparent that there will be no simple solutions to this very complex problem.

Part of the problem with hydrogen cyanide is that we are not sure when and where the hydrogen cyanide is being produced. The experts do not agree if it is limited to the visible fire smoke or if it exists outside the visible fire smoke. We are not sure if it is concentrated around a fuel that is off-gassing cyanide or it is distributed throughout the scene. Experts disagree about whether hydrogen cyanide is a bigger problem during the incipient stage, the free-burning stage, or during overhaul.

The potential sources of cyanide are everywhere in modern society. Is hydrogen cyanide released when a piece of electronic equipment in a plastic housing (a computer, laser printer, or fax machine) overheats and firefighters are called to check for the source of an unusual odor? Can the plastic handle of a pan on a stove release toxic amounts of cyanide at what otherwise might be considered a “food on the stove” fire? Is it realistic to mandate that firefighters wear SCBA any time they are potentially exposed to any type of visible smoke or unusual odor?

Shortly after the cyanide poisonings occurred in March 2006, I was working a night shift. One of the members was celebrating his birthday, and, following a tradition at my station, we had a birthday cake with candles. We sang a sloppy version of “Happy Birthday.” As the members sang and the candles burned, a small cloud of smoke formed. As I watched the cloud grow larger, it dawned on me that strict adherence to a mandatory mask regulation would require that every member present have on their mask. Then my mind flashed to a children’s birthday party and the absurdity of prohibiting candles on a birthday cake. How do we draw the line when mandating that firefighters wear SCBA whenever exposed to smoke? Do we treat grown men and women like children? Do we make an exception for birthday parties?

The following day, we had a house fire. As I approached the scene, my vehicle was engulfed in smoke more than two blocks from the house on fire. Should I have backed up, turned around, and gone in from a different route (which might have had smoke that was just as bad)? Should I have stopped the vehicle, donned my SCBA to drive the remaining two blocks, and worn my SCBA at the command post? Should I have set up my command post three blocks from the fire scene?

At the core of the SCBA compliance problem is recognizing when an atmosphere is safe and when it is not. Is visible smoke an adequate indicator of a hazardous atmosphere? How visible is visible? What if there is an odor in the air but no smoke is visible? Does a small cloud of smoke at the end of a hallway require all members to don their SCBAs? Do we allow firefighters to use their experience and judgment in making the decision to wear their SCBA? Do we seriously expect firefighters to don their SCBA at the slightest indication of smoke? By mandating enhanced compliance with SCBA regulations, aren’t we asking firefighters to do a better job of guessing when the atmosphere is safe or not safe?

No firefighter believes it prudent to use SCBA unnecessarily in a noncontaminated atmosphere. A firefighter’s air supply is a very precious resource. Accountability requirements dictate that a company withdraw from a contaminated atmosphere when any of its members have a low air supply. The ability of a company to accomplish a tactical objective is thereby limited by the air consumption of the member who uses up his air first. For a variety of reasons, firefighters are culturally conditioned to go on air as late as possible to maximize the length of time they have to operate in the contaminated area. Firefighters are also prone to remain in a contaminated environment once they have exhausted their air supply if the area is tolerable.

Addressing the enhanced use of SCBA will take more than well-intentioned admonitions to wear face masks more frequently. It will require fundamental changes at the firefighter, company officer, and command levels, as well as budgetary and administrative changes. Firefighters donning their face masks sooner at a fire and exiting the building with enough reserve air left to make it out of the contaminated environment before removing their masks will require more frequent rotations of personnel into and out of a building. More frequent crew rotations will have ramifications on staffing levels, the number of companies needed to effectively extinguish fires, accountability, resource tracking, increased radio communication, and command and control. It also raises questions about where air supply and entry times should be managed: at the company level or at the command post.

Among the most important operational recommendations that came from the Providence cyanide investigation was that firefighters need awareness training on cyanide, combined with cyanide detection equipment for use at fires. Instrumentation capable of detecting cyanide is available. Although no cyanide detectors have yet been designed to function in a fire environment, the Providence Fire Department is working with a company to develop such a device. Cyanide is by no means the only fire gas about which firefighters need to be concerned. Ultimately, a multigas meter capable of monitoring all of the important fire gases may be the solution.

Providing firefighters with proper instrumentation will eliminate the need to guess when an environment is toxic. Experience has shown that when expected to guess if the environment is toxic, firefighters are prone to guess in favor of getting to spend more time attacking the fire. Whether it is smoke from birthday candles, from food on the stove, or from a building fire, instrumentation can provide the answers to the unknown questions about hydrogen cyanide.

Among the other important recommendations of the Providence Fire Department cyanide investigation was that the fire department review its operational procedures for structure fires to take into account the need for more frequent crew rotation. Some of the sub-issues related to structure fire operations under consideration include the following:

  • Ensuring that a second engine company is assigned to each hoseline stretched, to allow for rotation of the first engine when its air supply is exhausted.
  • Ensuring the incident commander has enough command support to effectively manage the communication and accountability associated with more frequent crew rotations.
  • Determining where air management should be tracked: at the command post, at the division/group/sector level, at the company level, or by a designated air management officer.
  • Considering whether the added weight of 45-minute SCBA bottles will be justified because they decrease the frequency of mandatory crew rotations.

• • •

It is too early to know what the full ramifications of the Providence Fire Department cyanide investigation will be. Right now, we have generated more questions than we have found answers. Hopefully in a short time, the information in this article will seem relatively superficial to the average firefighter as our overall understanding of cyanide in fire smoke increases. However, we all need to bring ourselves and our departments up to speed on the hazards posed by cyanide in fire smoke.


1. Wallace, Deborah, “In the Mouth of the Dragon: Toxic Fires in the Age of Plastics,” 1990. (Garden City Park, NY: Avery Publishing Group, 1990).

2. Eckstein, M. and P.M. Maniscalco, “Focus on Smoke Inhalation-The Most Common Cause of Acute Cyanide Poisoning,” Prehospital and Disaster Medicine, (Mar-Apr 2006),, 21:2,

3. Alcorta, R, “Smoke Inhalation & Acute Cyanide Poisoning,” JEMS Summer 2004; Eckstein and Maniscalco, 2006.

4. Stephen W. Borron,.

5. Lactic acid is used as a measure of anaerobic respiration in the body. In a smoke-inhalation victim, high levels of lactic acid can be caused by carbon monoxide as well as cyanide. A high lactic acid level in conjunction with low carboxyhemoglobin levels indicates possible cyanide poisoning. However, a high lactic acid level in conjunction with a high carboxyhemoglobin level can mask the presence of cyanide.

6.; Baskan S.L.; CK Zoltani, GE Platoff, “Simulation Studies of Cyanide-Caused Cardiac Toxicity,” ARL-TR-3443 March 2005; ATSDR, 2004, 20, 39, 104.

7. Borron, Stephen W., article on, available at


9. Baskin and Brewer, 1997, 276, citing Paulet G, R. Chary, P. Bocquet, “The comparative value of sodium nitrite and cobalt chelates in the treatment of cyanide intoxication in non-anesthetized animals,” Arch Int Pharmacodyn 1969;127:104-117; and Haymaker W., AM Ginzler, RL Ferguson, “Residual neuropathological effects of cyanide poisoning in dogs: A study of the central nervous system of 23 dogs exposed to cyanide compounds,” Mil Surg.1952;3:231-246.

10. NIOSH Health Hazard Evaluation Report, HETA 81-276-1100, 1981.

11. “Fatalities among volunteer and career firefighters, United States 1994-2004,” CDC, MMWR, According to data at the U.S. Fire Administration Web site, an average of 12 firefighters per year die from heart attacks at fire scenes. See

12. Karter, MJ, JL Molis, “2004 U.S. Firefighter Injuries,” NFPA Journal, National Fire Protection Association, Nov. 2006.

13. “Report of the Investigation Committee into the Cyanide Poisonings of Providence Firefighters,” Providence (RI) Fire Department, May 30, 2006.

Hydroxocobalamin: A Possible Prehospital Antidote to Cyanide Poisoning from Smoke Inhalation



Based on the route of exposure, the duration, and concentrations, exposure to moderate or high levels of hydrogen cyanide can cause victims to become incapacitated within seconds to minutes. Without any treatment, death can occur within minutes to hours. Because of the toxic nature of hydrogen cyanide, the treatment of acute cyanide poisoning has to be based on a “presumptive diagnosis.” For successful intervention in smoke-inhalation patients with acute cyanide poisoning, treatment must be administered quickly-the closer to the time of exposure, the more successful the intervention will be.

In the United States, the prehospital treatment of acute cyanide poisoning from smoke inhalation consists of removing the patient from the source of cyanide and implementing supportive measures such as maintaining a patent airway, administering 100 percent oxygen, establishing an IV, and cardiac monitoring.

Effective cyanide antidotes exist in the United States, but their administration to patients is reserved for the hospital setting. The complexity of administering the antidote and managing the life-threatening complications prevent the use of the antidote at the fire scene. The antidotes include the Cyanide Antidote Kit (CAK), the Taylor kit, the Lilly kit, and the Pasadena kit. These treatments, however, can be dangerous for smoke-inhalation victims with concomitant carbon-monoxide poisoning.1 Therefore, the typical practice of administering antidotal treatment on the basis of a presumptive diagnosis of cyanide poisoning in the prehospital setting is discouraged in smoke-inhalation victims. (1) The CAK antidote involves a three-step administration of amyl nitrite, sodium nitrite, and sodium thiosulfate. Like carbon monoxide, the nitrites in the antidote reduce the oxygen-carrying capacity of hemoglobin, resulting in potentially lethal implications. The sodium nitrite can cause life-threatening hypotension when administered too rapidly.

In 1996 a cyanide poisoning antidote known as “hydroxocobalamin” received regulatory approval in France. Since that time, the Paris Fire Brigade has used it for victims of smoke inhalation, with documented success.

Hydroxocobalamin is a manmade “precursor” to Vitamin B-12. It can be administered in the prehospital setting to fire victims with suspected acute cyanide poisoning. It binds to the cyanide directly, creating cyanocobalamin, a natural form of vitamin B-12. The formed vitamin B-12 is then excreted from the body in urine.

The advantage of this approach is that methemoglobin is not produced and the oxygen-carrying capacity of the victim’s blood is not lowered.2 Hydroxocobalamin detoxifies cyanide without compromising the oxygen-carrying capacity of the blood or causing hypotension. Therefore, it is suitable for use in smoke-inhalation victims who may also have been exposed to carbon monoxide.

Also, administration of hydroxocobalamin based on “presumptive diagnosis” will not have any adverse effects on the patient if the degree of cyanide poisoning is not life threatening. It is believed that hydroxocobalamin offers a favorable risk-benefit ratio that allows for its use in the prehospital setting. (1)

The most common side effect of hydroxocobalamin is temporary pink discoloration of the skin, urine, and mucous membranes. (2) It is currently under FDA review as an antidote for acute cyanide poisoning. Its approval is expected to increase survival rates of smoke-inhalation victims.


1. Eckstein M, Maniscalco, PM: Focus on Smoke Inhalation-The Most Common Cause of Acute Cyanide Poisoning. Pre-hospital Disaster Med 2005;(2):49-55.


KEVIN JUTRAS, a 24-year veteran of the fire service, has served the past 17 years in the Providence (RI) Fire Department, where he is a lieutenant. He has a B.S. in natural resources as well as in fire science.

The Three Fires



On Thursday, March 23, 2006, at 1031 hours, the Providence (RI) Fire Department responded to a building fire at El Fogon Restaurant, a fast food restaurant at 1197 Broad Street. The building was a one-story structure with a mansard-like, wood-frame façade roof. The fire began in the ductwork above the restaurant’s frying equipment and extended quickly into the roof and void space within the façade. Most of the firefighting was done from the exterior because the void space was not accessible from inside the restaurant. The soffits beneath the façade were opened from below with plaster poles, exposing the fire in the voids.

(1-4) The fires discussed in this article were not major fires. They were very much run-of-the-mill fires that occur every day in every city and town. (1) Broad Street fire building, front.

After the fire, a member of Engine 3’s crew began to experience symptoms including headache, dizziness, difficulty breathing, and a cough. Members also reported that at times he was talking incoherently. At 1415 hours, the member was transported to Rhode Island Hospital, a Level I Trauma Center and teaching hospital affiliated with Brown University Medical School.

(2) Broad Street fire building, rear.

In the emergency room, Dr. Kenneth A. Williams, MD, FACEP, clinical associate professor of emergency medicine at Brown University Medical School, happened to walk past the firefighter and instructed the attending physicians to check the member for cyanide poisoning in addition to carbon monoxide poisoning.

When the member’s blood tests came back, his whole blood cyanide was 57 mcg/dL. Rhode Island Hospital considers any level higher than 20 mcg/dL as toxic. The member was treated for cyanide poisoning and given antidote therapy. The department informed all of the members who responded to the Broad Street fire and recommended that if any were experiencing symptoms of cyanide poisoning they should go to Rhode Island Hospital to be examined. Sixteen members sought medical attention; 14 went to Rhode Island Hospital. Of these 14, three were found to have whole-blood cyanide levels above 20 mcg/dL.

At 1735 hours on March 23, 2006, the Providence Fire Department responded to a fire in a three-story, wood-frame, six-unit apartment building at 125 Knight Street. Because of the extended time of the Knight Street fire, most of the personnel who had been working at the Broad Street fire had been relieved and a different shift was working. Because the fire occurred in a different part of the city, many of the units that responded to the Knight Street fire had not responded to the Broad Street fire. The Knight Street fire was uneventful. The fire was confined to one apartment on the first floor and was determined to have been caused by the careless disposal of smoking materials. No injuries were reported.

(3) Knight Street fire building.

At 0207 hours on March 24, 2006, the Providence Fire Department responded to a house fire at 70 Ralph Street. All of the units that responded to the Ralph Street fire had previously responded to the Knight Street fire. The fire was confined to a bathroom and was determined to be accidental. At approximately 0223 hours, just after the Ralph Street fire was placed under control, the driver of the first-in engine, Firefighter Kenneth Baker, collapsed at the scene, suffering a heart attack. Baker was immediately attended to by emergency medical personnel, provided with advanced life support on-scene, and promptly transported to Rhode Island Hospital, where he was successfully resuscitated. In light of the cyanide poisoning cases from the previous day, Baker was tested for cyanide. The lab results showed that he had a whole-blood cyanide level of 66 mcg/dL.

(4) Ralph Street fire building. (Photos by author.)

After consulting with doctors at Rhode Island Hospital, all members who responded to any of the three fires were instructed to go to Rhode Island Hospital if they experienced any symptoms that could be related to cyanide poisoning. Twenty-eight sought medical care; 27 had their cyanide levels tested. Eight members tested high (above 20 mcg/dL) for cyanide.

Providence Fire Chief David D. Costa immediately appointed a five-person team to investigate the cyanide-poisoning cases. After two months of work, the investigation committee concluded that Baker’s cyanide exposure occurred at the Knight Street fire. His company officer at the Knight Street fire was found to have had a whole-blood cyanide level of 72 mcg/dL, compared with Baker’s 66 mcg/dL. The two members operated side-by-side throughout the Knight Street fire. Neither member responded to the Broad Street fire. This officer was relieved shortly after the Knight Street fire and did not respond to the Ralph Street fire.

The investigation uncovered cyanide-containing fuels at all three fire scenes. At the Broad Street fire, foam insulation, rubber roof membrane, tar, and fiber-reinforced plastic were involved. At the Knight Street fire there were a crib mattress, plastic bags of clothing, plastic toys, electronic devices (television, stereo, the exterior of which were made of plastic), a mattress, a box spring, and wall-to-wall acrylic carpeting with foam padding underneath. At the Ralph Street fire, the fire melted a fiberglass tub and burned numerous plastic items. As is evident from the post-fire photos, none of the three fires was a spectacular fire. They were relatively ordinary fires, the types that occur hundreds of times a year in Providence and thousands of times a year across the United States.

No posts to display