The Chemical Suicide Phenomenon


Chemical suicides have plagued the United States since 2008 and continue to be on the rise. This method of suicide originated in Japan in 2007, where authorities have seen more than 2,000 such cases. Chemical suicide, sometimes called detergent suicide, involves mixing common household chemicals to create deadly hydrogen sulfide (H2S) gas, which can quickly reach lethal concentrations in confined spaces. In 2008, first responders in the United States responded to three incidents; in 2009, there were nine incidents; in 2010, there were more than 30 incidents. It is important to realize that analysts suspect these numbers are likely considerably higher because of underreporting in the United States.

H2S is a colorless gas with an associated strong odor of rotten eggs or sulfur. It is produced naturally by biological decay of sulfur-containing goods such as fish, sewage, and manure and is a by-product of industrial chemical processes such as petroleum refineries, mines, and hot asphalt fumes. H2S is also produced naturally in sulfur hot springs and in underground natural gas collections.

In concentrated forms mixed for use in chemical suicides, H2S is extremely toxic when inhaled, posing a significant risk to first responders without proper respiratory protection who encounter a chemical suicide victim or who are unaware of its presence. H2S is a chemical asphyxiant and a chemical irritant. As an asphyxiant, it kills by rendering cells in the body unable to use oxygen, effectively suffocating its victim at the cellular level much like hydrogen cyanide (HCN), a major killer of fire victims.

As a chemical irritant, H2S irritates the eyes and upper airway. At high concentrations, it can cause death after just a few breaths. H2S is also an olfactory nerve paralyzer, meaning it will rapidly deaden the sense of smell, even when present in low concentrations. Overall, 25 percent of deaths associated with hydrogen sulfide gas occur in rescuers, first responders, bystanders, and professionals who handle H2S on a regular or routine basis. To date, there have been no deaths to first responders involving chemical suicides.


H2S has a vapor density of 1.19, making it heavier than air. First responders monitoring the atmosphere while approaching the scene of a suspected chemical suicide can expect to find vapors lower to the ground. However, once they enter the space or initiate air monitoring within the space, it can be expected that diffusion will have occurred, completely filling the space with vapors. Vapors may be knocked down with a water spray if that course of action is best for the incident; however, contain all runoff and properly dispose of it, as it is toxic and corrosive. If released in an enclosed space (such as a vehicle), H2S may be absorbed into interior surfaces. Venting a vehicle or other enclosed space may not necessarily reduce atmospheric levels below an immediately dangerous to life and health (IDLH) atmosphere; H2S will continue to off-gas from surfaces where it has been absorbed.

Hydrogen sulfide is made by mixing hydrochloric acid with a sulfur-containing compound (in high enough concentration to react with the hydrochloric acid). In many of the cases we have seen, the two chemicals mixed were hydrochloric acid and lime sulfur. Lime sulfur (Bonide®) is a 28-percent solution of calcium polysulfide. Both products are easily obtained at local hardware, grocery, or big box stores. Approximately one-half cup of each product will produce about 1,000 parts per million (ppm) H2S inside the passenger compartment of an average-sized vehicle or other small confined space (approximately 3,500 cubic feet). Individuals attempting chemical suicide often mix several containers of each product, increasing the volume of gas produced without increasing its concentration. Since one of the chemicals is an acid and the other is a base, expect a mildly exothermic and somewhat violent reaction. Because of this, evidence of the chemical reaction may be visible from outside of the confined space. H2S also causes the surfaces of copper and silver coins as well as jewelry to darken or turn black.

Personal protective equipment (PPE) for chemical suicide incidents involving hydrogen sulfide should be adequate and appropriate for the degree and type of contamination encountered. Each incident will be slightly different, and PPE needs will vary accordingly. The IDLH threshold set by the Centers for Disease Control and Prevention (CDC)/National Institute for Occupational Safety and Health (NIOSH) for hydrogen sulfide is 100 ppm; above this level, self-contained breathing apparatus must be used. Chemical protective clothing is not necessary and generally is not recommended for response to H2S gas incidents. H2S poses a minimal risk of cutaneous (skin) absorption and minimal risk of secondary contamination of first responders except when resuscitating a victim. Even with victim decontamination, unprotected exposure of rescuers to vomit, lung, and other body fluids can be harmful to EMS providers. Structural firefighting turnout gear or Tyvek® suits provide adequate skin protection.

Atmospheric monitoring is imperative when approaching the scene and throughout the duration of the incident to protect responders’ health and safety. Trained personnel using a standard fire service four-gas monitor that includes H2S can readily perform the monitoring.

H2S, by Department of Transportation definition, meets the criteria for a flammable gas. It has a flammability range of 4.3 percent to 45 percent. The autoignition temperature is 500°F. However, in these particular situations, the flammability risk is fairly low. To ensure first responder safety, eliminate all ignition to reduce the flammability risk. Have a charged handline ready in case an ignition source is found. Properly ventilate the vapors in the space once all precautions have been taken to accomplish this safely.


Set up appropriate decontamination for first responders for the degree of contamination encountered. A full technical decontamination setup may not be necessary, or appropriate, for the incident. At minimum, wash the skin with water for three to five minutes. If eyes or skin appear to be irritated, continue to flush with water during medical observation and transport to a nearby medical facility

Contamination for victims of chemical suicides will be more acute, and decontamination will require more time and attention. Remove and double-bag clothing. Decontaminate the body as dictated by normal standard operating procedures or guidelines. Victims may off-gas from their lungs after they have been deceased for a significant time. This may pose a risk for those transporting victims and performing autopsies. Body bags are recommended for transporting victims only if victims must be transported in an enclosed vehicle in which they will be occupying the same space as the driver. The best option for moving a victim of chemical suicide would be to wrap him in sheets and tarps and transport him in an “open” vehicle such as an official pickup truck (i.e., one belonging to the local police/sheriff’s department or fire department vehicle).

Establish protocols in a preplan prior to the occurrence of an incident. The county coroner’s office, the local hospital to which a contaminated victim may be transported, and local transporting agencies should be involved in the writing of these protocols.


H2S will act as a mucous membrane and respiratory tract irritant. In extremely high concentrations, it may also act as a skin irritant. Low concentrations include anything below 50 ppm. Symptoms associated with exposure to low concentrations of H2S include irritation to the eyes, nose, throat, and upper airways. Higher concentrations result in more significant symptoms, including central nervous system stimulation (excitability, tachycardia, tachypnea, and significant headache), which precede central nervous system depression (dyspnea, impaired gait, dizziness, bradycardia, syncope, respiratory failure, and death).

Immediate or delayed (up to 72 hours) pulmonary edema is also associated with exposure to high concentrations of H2S. Other symptoms associated with H2S exposure may include photophobia (abnormal sensitivity or intolerance to light) and a taste of garlic in the mouth.

Treatment for H2S exposures involves supporting cardiovascular and respiratory function. Nitrites are recommended: Give amyl nitrite by inhalation for 15 to 30 seconds every minute until intravenous access can be obtained. After this, administer intravenous sodium nitrite, 300 milligrams over two to four minutes (for adults) or more slowly if hypotension ensues. This may aid recovery by forming sulfmethemoglobin, thus removing sulfide from combination in tissue. This treatment is most effective if started shortly after exposure. Treat seizures with benzodiazepines and hypotension with fluids and pressors if needed.


H2S has a rate of decay ranging from 12 to 37 hours, depending on the ambient air temperature. The colder the ambient air, the longer the rate of decay. The warmer the ambient air, the shorter the rate of decay.

Instructions for chemical suicides are readily available on the Internet. Most sites encourage anyone planning to use this method to appropriately warn people who might respond to the suicide of the presence of the deadly gas. Newer versions of Internet instructions provide very explicit information on how to make and generate H2S gas. Premade signs continue to be available as well. The easily recognizable incidents will have signs posted in the vehicle windows or inside the structure, as is the case 90 percent of the time. There are, however, the not so easily recognizable incidents where no signs are present and there is little in the way of clues. That is why we need to have a heightened sense of awareness.

In several incidents, individuals manufactured HCN instead of H2S. The finding of HCN is rare because the chemicals needed for the reaction are not as readily available as the chemicals used to make H2S. It is important that you differentiate between H2S and HCN. Atmospheric monitoring coupled with obvious signs and evidence of chemical reactions will ordinarily point to H2S. Some EMS providers have mistakenly believed that H2S chemical suicide victims can be treated with hydroxycobalamin (Cyanokit®), the preferred cyanide antidote for resuscitating smoke-inhalation victims. Other cyanide antidote kits (CAK) contain amyl nitrite, sodium nitrite, and sodium thiosulfate, which, in combination, are used to treat cyanide poisoning. The nitrite components of a CAK are useful for treatment of H2S poisoning. Do not give sodium thiosulfate. Hydroxocobalamin, while incredibly effective in reversing the effects of cyanide poisoning found in fire victims, has no utility in H2S chemical suicides.

Thoroughly check the scene before attempting to enter or open a vehicle with unresponsive patients inside. Observe a “10 seconds to save your life” rule: Take an extra 10 seconds during size-up to peer into the vehicle and look for pails, buckets, or other mixing vessels in the front or rear seats; containers of acids and pesticides; a yellow or green residue in the vehicle; and vents that may be taped off. If the incident occurs in a structure, such as an outbuilding or other contained area, no written warnings may be present. Be extremely cautious when investigating suspicious odor calls inside a structure.

Currently, in the United States, the use of hydrogen sulfide or hydrogen cyanide has been limited to individual suicides. Approximately a half a cup of an acid-containing product and a half a cup of a sulfur-containing product will generate enough gas to fill a standard four-door sedan with more than 1,000 ppm of H2S gas. Most individuals mix several gallons inside their vehicles, generating in seconds an incredibly lethal atmosphere that will linger for several hours.

There is the potential for chemical suicide incidents to occur at middle and high schools. Intelligence obtained from Internet chat sites indicates a shift to younger and younger individuals interested in information on this method of committing suicide. There is concern that there will be a shift to the “suicide pact” method, as has been seen in the United Kingdom. Two or three students may make their way to the school parking lot and commit suicide using the H2S method.


The National HazMat Fusion Center has established best practice guidelines for a response to a chemical suicide incident. The information is available in a flowchart and may be downloaded from its Web site, Laminate the flowchart, and place it in all response vehicles. You can also obtain a copy of this chart at the Fire Engineering Web site at

If you have not been called to a chemical suicide, you will be. It is essential that you recognize the clues of H2S, maintain a safe distance, and approach only with appropriate PPE and proper atmospheric monitoring. If treatment is needed, EMS providers should be prepared to deliver care while protecting themselves from exposures. As noted, all department response apparatus should have a readily accessible copy of the best practice guidelines for response to chemical suicide incidents from the National HazMat Fusion Center. It is inexcusable for any responder to be exposed during a response to a chemical suicide.


MICROMEDEX® Healthcare Series: Thomson Micromedex, Greenwood Village, Colorado (accessed July 2011).

Genium’s Handbook of Safety, Health and Environmental Data for Common Hazardous Substances. New York: McGraw-Hill, 1999.

Chemical Hazard Response Information System (CHRIS) Manual. Washington DC: U.S. Coast Guard, 2006.>

NIOSH Pocket Guide to Chemical Hazards. Cincinnati: NIOSH Publications, 2011.

Currance P, Clements B. and Bronstein A. Emergency Care for Hazardous Materials Exposure (3e). St. Louis: Mosby/JEMS, 2007.

Fire Protection Guide to Hazardous Materials. Quincy: National Fire Protection Association, 2010.

Agency for Toxic Substances and Disease Registry. Centers for Disease Control:

JACOB ORESHAN III is a deputy chief with the New York State Office of Fire Prevention & Control. He has been in the fire service for 24 years and volunteers with the Boght Community Fire Department in Colonie, New York.

TERESA STEVENS is a fire protection specialist with the New York State Fire Office of Fire Prevention & Control. She has an A.A.S. in fire protection technology.

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