Prevention of Inhalation Injuries

In the emergency response professions there are many examples of inhalation exposures to combustion gases and even chemicals. Most of these exposures are preventable but some may not be especially with chemicals that have poor or even non-existent warning properties. Consequently, responders need to be constantly vigilant so they may avoid needless inhalation exposures.

To become more aware of the dangers of inhalation exposures consider the following case studies;

New York
On a cold December day two state troopers were overcome by toluene diisocyanate vapors after being involved in a spill on a highway. These law enforcers walked in the spilled material during the incident and when they returned to their own cruisers the heat in their vehicles warmed the material on their shoes and caused it to vaporize. The vapors were concentrated enough to make both of them pull over to the side of the road a short time later and radio for help. The arriving medical personnel found both troopers unconscious in their cruisers, removed them, and transported them to the hospital. Both troopers retired on disability and one died from complications a short time later.

In a September incident a refinery worker slipped and fell into a vat of hexane on a warm evening. The vat was four feet deep and the worker managed to keep his head above the liquid. An ambulance crew treated the worker at the scene by removing all the patient's clothing and giving high concentrations of oxygen. Despite these actions, the patient's condition deteriorated rapidly and a nearby medical transport helicopter was called for transport to a major area hospital. The patient arrived at the hospital alive, was treated and kept for observation for two days. The original ambulance and its crew, the medical helicopter and its crew, and the hospital emergency room became contaminated in the patient care efforts. Additionally, all emergency workers experienced temporary headaches, dizziness, and nausea from their exposure to the hexane vapors.

One January day in Broward County, Florida an engine company responded to a report of an odor of smoke at an apartment complex. Upon arrival there were no signs of fire or smoke but an employee directed the crew to a back bedroom of an apartment where smoke had been seen. The crew felt the door and found it to be cool to the touch and they did not observe any smoke. When they opened the door chemical vapors hit them and they were immediately overcome. It was found that the room contained concentrated vapors of sodium hydroxide, a white powder that had gotten wet and reacted. There were other chemicals present in the bedroom, which had been a storeroom for the apartment complex. One firefighter's blood tested immediately after the incident revealed high levels of chloroform and PCB's (polychlorinated biphenyls). All three firefighters suffered disabilities from the incident.

Inhalation Physiology

Inhalation is the number exposure route for unprotected responders because of the necessity of breathing to survive and also because of the exposure area within the lungs. There are millions of alveoli where oxygen is absorbed from the lungs into the bloodstream and unfortunately other gases can enter the blood through this 2 or 3-cell thick interface. If the surface area of these alveoli were laid out on a flat surface the average adult's lung tissue would cover approximately the size of a single tennis court. This massive surface area provides a toxic gas or vapors a great opportunity to cause harm. Magnify this area with the number of times per minute that a person inhales and exhales, especially while exerting effort, and it is easy to see why inhalation injuries often have immediate (acute) effects. Additionally, when the chemical agent enters the bloodstream more harm can occur.

Structure Fire Inhalation

Excellent examples of the dangers of inhalation exposures to combustion gases are numerous. The February 27, 1975 fire in New York City at a New York Telephone Company is noteworthy because of the approximately 239 firefighters who required medical treatment on the day of the fire many of them developed chronic health problems in the ensuing months and years. Soon after the fire dozens of those firefighters developed several types of cancer including throat and larynx cancers. Many of those firefighter victims met a premature death as a result of the acute exposure at the fire to gases emanating from burning plastics and wire insulation.

It is also a well-known fact that many fire victims die as a result of inhaling toxic gases such as carbon monoxide and even hydrogen cyanide. In the average structure fire smoke many toxic compounds are generated with poisonous and carcinogenic qualities. In addition to those poisonous and chemical asphyxiants listed above the following gases are also evolved at nearly every fire as a result of our chemical world;

Hydrogen Chloride
Hydrogen Fluoride
Nitrogen oxides
Strong irritant
Poison, irritant, carcinogenic
Poisonous and asphxiant
Poisonous, caused by decomposing refrigerants
Poison, cause lung edema
Poison, irritant, caused by burning plastics

Chemical Fires

Chemical fires are equally as dangerous. A 1969 fire at a Fort Lauderdale, Florida fertilizer facility also has destroyed the lives of numerous firefighters and their families. Many forms of cancer started showing up in the firefighters several years after their exposures at this fire. The 1960's were the days when self-contained breathing apparatus were not used very often even if they were available. The firefighters did not wear any scba's the day of the fire and now their cancers can be traced to the incident at the fertilizer company. Through research by the local union it was found that the company had 39 compounds in which a dozen could be linked to cancer. Not surprisingly, the group of firefighters who fought the toxic fire has a rate of cancer that is 15%, nearly 6 times the normal cancer rate.

In a recent local fire that involved the combustion of the metal zinc at a casting company two firefighters developed metal fume sickness as a result of their inhalation to the zinc fumes. Despite several warnings to "mask-up" two of the three firefighters who entered the smoke-charged building did so without the protection their scba's afford. The third firefighter masked-up immediately upon entering the building and consequently did not develop any symptoms. Even though the exposed firefighters went to the hospital for an evaluation after the fire, later in the day they developed the symptoms of headaches, metallic taste in their mouths, and elevated body temperature, which is consistent with metal fume fever. This type of illness is usually transient (symptoms generally pass within 2 or 3 days) but can be life threatening if the exposure is great enough.

What do all of these inhalation exposures have in common? They were all preventable! Adequate use of scba's may have prevented the dire consequences that followed these incidents. Many departments stress the dangers of smoke and hazardous atmospheres and the use of protective equipment and even have standard operating guidelines or procedures in place to prevent responders from becoming victims yet these exposures continue to happen. As an industry, we have to change our approach to these situations. Prevention is the key!

Odor Investigations

Generally speaking, no exposure to combustion products is safe but when we respond to odor investigations we confront a dilemma; if we mask-up we will not be able to "sniff-out" the source of the odor and if we do sniff-out the source we may become over-exposed. Over-exposure is likely especially on investigations involving the toxic products of combustion and also with chemicals.

Odor investigations are common responses and in an article by FDNY's Battalion Chief Frank C. Montagna it is stressed that they should be investigated fully. Chief Montagna states that the common causes for odor investigations are;

  • food on the stove or in the oven
  • combustion materials in wastebaskets or even in bathtubs, sinks, or toilets
  • faulty flues
  • clothes dryers, washers, dishwashers
  • light ballasts
  • combustion materials that were placed in closets or too close to other materials

Chief Montagna stresses to use our educated noses when we search for the source and to become good detectives. Interview appropriate people that can assist with the identity of the odor's source. Also, return to fresh air periodically to freshen your sense of smell. Remember too, to utilize thermal imaging cameras to assist with finding hot spots that may be sources for odors. Finally, Chief Montagna warns to not give up when looking for smoke or electrical odors; your efforts may save lives. With all of these investigations be wary of any and all inhalation exposure!

Anhydrous Ammonia
Butyric Acid
Carbon Disulphide
Hydrogen Cyanide
Toluene Diisocyanate
Rotten Cabbage
Bitter almonds
Moth balls
New mown hay
Solvent, rubbery
Medicinal, pungent

Chemical Odors

One warning of chemical exposure we can use is the sense of smell. Many chemicals do have strong odors but be cautious because awareness of their presence may cause over-exposure. Some well-known chemicals with distinct odors are listed below;

Also, it is important to keep in mind that some chemicals do not have detectable odors or may have poor warning properties. These materials are very dangerous to unprotected responders because over-exposure may not be noticed until toxic effects become apparent. Effects include dizziness, confusion, slurred speech, and nausea. Some of those materials are listed below;

Carbon monoxide
Hydrogen sulfide
Methylene chloride
Ammonia odor, poor warning properties
Rotten eggs, cautious of olfactory fatigue
None, odorant added for detection
Sharp, ether smell, poor warning properties
None, odorant added for detection

Additionally, some chemicals may be detected through the sense of smell only to "disappear" a short time later. This happens because of olfactory fatigue. The chemical may still be present it just cannot be detected by smell. Chemicals that cause olfactory fatigue and those that cannot be detected by smell must be regarded as serious threats to responder health and safety. The only method of reliably detecting the presence of such chemicals is with properly selected and maintained monitoring instruments.

Odor Thresholds

Many of the chemicals that have odors possess what is called "odor thresholds" or a range in which the average person can detect their presence through the sense of smell. There are many sources of this information but one source that has spent millions of dollars researching and developing a respirator guide is from the 3M Company. The alphabetical listing of chemicals in the guide was developed to assist respirator users in selecting the proper respirator for use in specific chemical environments.

Up until 1998 it was permissible to use odor thresholds to indicate when cartridge type respirators had reached the end of their service life. It is called "breakthrough" when the wearer can detect the chemical odor inside the respirator. An exit of the area and a cartridge change would be in order. A rule change by OSHA in 1998 now prohibits using breakthrough as the end of service life indicator because it has been found the odor threshold range was not reliable. One worker may smell the chemical breakthrough much sooner than another worker so this individual difference may lead to over-exposure. Obviously, breakthrough is not a concern for responders who wear scba's.

Odors and odor thresholds for specific chemicals may also be found in MSDS's. As for investigations particular odors may assist responders in quickly identifying the source and hazard in order to avoid exposures. Some private industries even have their employees sniff samples of chemicals in order to better detect them in the event of a release. The table below lists many chemicals, their odor, and both the pre-1998 odor threshold range along with the post-1998 odor threshold that can now only be used as a reference.


Anhydrous Ammonia
Carbon Disulphide
Hydrogen Cyanide*
Hydrogen Sulfide

Solvent, aromatic
Rotten Cabbage
Bitter almonds
Rotten eggs
Poor warning
Moth balls
New mown hay
Solvent, rubbery
Medicinal, pungent
Only half of the population can detect the odor of HCN because of genetic reasons.
Source; 3M Respirator Selection Guide
Available through Occupational Health & Environmental Safety Division at 800-243-4630

Firefighters and Sense of Smell

A November 9, 1999 article by Marilyn Elias in USA Today entitled "Firefighters risk losing sense of smell" revealed that testing by the Smell and Taste Treatment and Research Foundation found firefighters to be at risk of losing their sense of smell. Neurologist Alan Hirsch tested 102 Chicago firefighters and found that 48% had a compromised sense of smell despite the use of scba's during their careers. It was also found that these firefighters could not disseminate natural gas or smoke odors from perfume or soap bubbles. One theory for the findings may be that firefighters take their scba's off after the fire is extinguished. This action may compromise the sense of smell. This study should send a red flag up that indicates responders should not rely on their sense of smell as much as in the past.

Terrorism and Sense of Smell

Many chemical weapons of mass destruction also exhibit an odor, especially with impurities. The following table indicates the odors that are commonly associated with these chemical agents.

New mown hay
Bleach or swimming pool
None to Fruity
None to Fruity, (Juicy Fruit gum)
N series
Phosgene Oxide/CX
Garlic odor
Fish odor
Irritating, disagreeable
Hydrogen Cyanide/AC
Cyanogen Chloride/CK
Bitter almonds or peach kernels
Source; Domestic Preparedness Training by Department of Defense

Clandestine Drug Laboratories

One last site in which responders may confront odors that could lead to over-exposure of the respiratory system is at illegal or clandestine drug laboratories. Irritating and toxic odors abound in and around these sites. Be aware of these odors with their potential sources and hazards;

Hydrochloric acid
Sodium hydroxide
Sulfuric acid
Fingernail polish remover
Pungent or "cat urine"
Sharp, sweet
Benzene like, aromatic
flammable, narcotic
flammable, anesthetic
corrosive, irritant
caustic, toxic if airborne
corrosive, toxic if airborne
toxic, flammable

Response Actions

Nearly every fire and every odor complaint we respond to have the potential to cause harm because of the chemical world we live in. Knowledge and recognition of what we may be exposed to at these emergencies can prevent needless exposures. It is far better to don our scba's and prevent problems than to expose us to a toxic, dangerous environment. Even though effects may not be apparent at the time of the exposure many small exposures can cause delayed or latent effects. It is in the best interest of all to avoid those problems. When in doubt wear your scba; it less expensive than health problems later in life!

A simple acronym to keep in mind at all incidents is "ASAP" and it stands for "Always Suspicious-Always Prepared". This acronym can become a defensive philosophy in which all responders should subscribe to prevent injuries. At every incident ask yourself "what could harm me in this present circumstance" and then act appropriately. Don your scba facepiece if in doubt, stay out of known and visible vapor clouds and smoke unless adequately protected, use available monitoring instruments to detect contaminants, and seek medical advice or care if you have been exposed. Remember what the wise, old Father of the fire service, Benjamin Franklin, once said; "An ounce of prevention is worth a pound of cure". It is as true today as it was in the 1700's.