Stress: The Silent Killer

Photo found on Wikimedia Commons courtesy of Magmer  


By George H. Potter

Firefighters and other emergency responders are exposed to an infinite number of hazards during their responses and interventions in fires, road traffic accidents, hazmat incidents, urban search and rescue, high-angle rescue, and many other types of incidents. Each response exposes the responders to a few or many physical and mental hazards, all of which may or will directly expose the responders to a very specific and extremely dangerous pathology: stress.

Stress can be defined as physical and or psychological fatigue produced by excessive physical activity and which produces a significant increase of body temperature during the realization of that activity. This stress can be physical, mental, and/or psychological and must be detected and treated immediately and adequately. If not treated, or if treatment is overly delayed, it will be a significant contributing factor to serious injury or possibly death.

Emergency responders are always exposed to stress provoking situations: intense fires, complicated rescue operations, or prolonged hazmat incidents. All require a physical exertion far superior to that normally experienced in day-to-day activities, except possibly training exercises and drills. Mental or psychological stress may be the result of injuries to or the death of companions or victims in incidents. This is often referred to as posttraumatic shock. It is far too well known that some members of the Fire Department of New York are still psycologically affected by September 11.

This article will cover heat stress and how to recognize it, treat it, and control it. This is probably one of the most important functions of the safety officer during and after strenuous interventions.

Heat stress can be caused by an almost infinite number situations and conditions. Even during a “normal” duty tour during which no emergency response actions are being undertaken, personnel serving in stations situated in hot climate regions can be exposed to the phenomena, while performing possibly strenuous actions such as station or vehicle cleanup, physical fitness activities and even prolonged exposure to direct sunlight.

However, the most common situations that can subject emergency responders to heat stress are precisely that—responses to and operations in and around emergency incidents. The following are a brief selection of those innumerable scenarios.

EMERGENCY 1: Confined fire in an average single family residence in a small/medium residential community

The emergency response team consists of an engine with a crew of three (driver/operator + two firefighters), a ladder with a crew of three (driver/operator + 2 firefighters), a tanker manned by the driver/operator + 1 firefighter, an ambulance with a two-person crew, and the incident commander (IC). Total staffing = 11.  

The fire spreads rapidly throughout the building. Standard operating procedures (SOPs) will typically call for size-up by the IC, the water supply from the tanker to the engine, a ladder crew to prepare for entry-search-rescue-vent, the engine crew to advance attack hoseline(s), and the ambulance to prepare to assist possible victims. The town’s single fire department does not have resources for establishing rapid intervention team (RIT), so everyone on scene has his work cut out for him. The town may have a mutual-aid agreement with nearby municipalities that could or could not place similar resources on scene within a reasonable time frame.  If this incident takes place in a hot climate area in mid-summer, and backup resources are not immediately available and may well take at least a half-hour to enter, search, locate the fire and possible occupants, attack the fire, extinguish it, perform overhaul, and recover material, it is quite likely that at least four team members may become exposed to heat stress. This would be because of the following:

  • Heat generated by the fire itself, possibly up to or exceeding 700°F.
  • Heat retained inside the firefighters’ (certified) personal protective equipment (PPE).
  • Physical exertion in the performance of assigned firefighting actions.
  • If the incident occurs during the early morning hours, certain physiological stress may affect some members because of the almost instantaneous change from the physical mode of “deep” sleep to that of total mental and physical awareness and state of alert.


EMERGENCY 2: A confined fire in a large office space on the 25th floor of a high-rise, multiuse building in a medium/large municipality.

The “typical” response team to this incident would probably be three engines with crews of four each (driver/operator + 3 firefighters), two ladders with crews of four (driver/operator + 3 firefighters), one rescue squad with four members, one self-contained breathing apparatus (SCBA) air resupply unit with two more people, an IC with an aid who acts as safety supervisor, and at least one ambulance with two emergency medical technicians (EMTs).

The city’s fire department has sufficient resources to dispatch at least one four-person RIT and, if needed by the IC, two, four, or more fully staffed engines and a couple of additional ladders. So, the composition of the initial on-scene first response resources includes 3 engines, 2 ladders, 1 squad, and the air unit manned by some 30 fire/rescue personnel with the possibility of anywhere from four to 16 or more additional firefighters, which totals nearly 50 persons immediately on scene . A large city fire department would be able to place double that number on scene during the initial minutes of the incident.

This incident would last several hours and would be exceedingly demanding physically. The SOPs for this kind of fire would call for simultaneous enter-search-rescue-vent; locate, attack, contain, control, and extinguish the fire; overhaul; and material recovery. A large number of these responders would be susceptible to heat stress because of the following:

  • Physical exertion by climbing stairs from ground up to advanced command point (floor 23 or 24) carrying SCBA, hoselines, and other equipment.
  • Heat generated by the fire, again possibly exceeding 700°F.
  • Heat retained inside (certified) PPE.
  • Physical exertion in the performance of firefighting actions.
  • Possible physiological stress if the incident occurs at night.


EMERGENCY 3: A major hazmat incident involving the failure of piping in an elevated process unit of a chemical manufacturing plant on the outskirts of a medium-sized municipality.

The chemicals involved present multiple hazards such as flammability, toxicity, and violent reactions if mixed with other substances present in the facility. The plant has a small, full-time industrial emergency response team, and the municipality’s fire department has a specialized hazmat response unit. The initial response to this emergency would likely be the in-plant team (3 responders trained in fire and hazmat incident response), the city’s hazmat unit, a truck staffed by 3 persons), two engines each crewed by four (all personnel with hazmat response training), one ambulance with two EMTs, one SCBA air re-supply unit with two persons, one IC with an aid acting as safety supervisor, which comes to six vehicles staffed by 20 qualified hazmat responders including the in-plant team. If necessary, the fire department could dispatch more qualified personnel, and the plant’s emergency response manager could mobilize more in-plant personnel. The engine companies initially responding to this incident would possibly have multiple assignments such as possibility of fire, intervention substitution, decontamination, and other possible actions.

In this incident, the in-plant response team would have to be prepared for the possibility of a fire and the actions required to locate and isolate the source of the leak; contain, control, and stop-off the leak; and contain, recover and dispose of the spilled substances and absorbent materials employed all while aided by the fire department’s hazmat team and all responders working in the hot and warm zones wearing full Level A PPE.

An incident of this nature could take several hours to resolve, meaning that personnel turnover—maximum of 30 minutes in the hot and warm zones—would be extensive; up to 12 persons per hour rotating plus backups. It could possibly require up to 30 or even more hazmat qualified responders as well as standby crews for possible fire intervention, decontamination, personnel, and other secondary personnel.

In this incident, heat stress would happen principally because of the following:

  • Body heat retained within the Level A PPE.
  • Physical exertion during the spill control activities.
  • Rapid rotation of intervening teams.
  • Possible physiological effects if the incident occurred at night.

Other types of incidents that would most likely provoke heat stress include wildland fires, multiple motor vehicle accidents, complex urban search and rescue operations, or aviation accidents. The list could go on and on.

Now, how can heat stress be identified; possibly prevented; or at the least reduced, controlled and treated? The safety officer or supervisor should be trained in heat stress treatment. This begins with recognizing certain tell-tale indications, sometimes very evident, but under various conditions very difficult to observe or diagnose.

Symptoms include (but may not be limited to) the following:

  • Profuse sweating.
  • Rapid breathing.
  • Dizziness.
  • Disorientation.
  • Increase of body temperature—up to 105°F.
  • Discoordination.
  • Thirst.
  • Muscle cramps.
  • Irritability.
  • Possible loss of consciousness.

If untreated, the heat stress could contribute to heat stroke which, in turn, could provoke serious physical problems, and could possibly even be fatal.



  • Affected person(s) should sit or lie down.
  • Elevate feet 10 to 12 inches.
  • Remove helmet and gloves.
  • Open his jacket.
  • Provide a refreshment; cool/chilled drinks, NOT ice-cold.

            – isotonic drinks

            – water

  • AVOID Alcoholic beverages – beer, wines, and so on.


If necessary, transport seriously affected person(s) to appropriate hospital for proper medical treatment. Complete information on the patient’s condition must be communicated to the hospital emergency reception.


  • Reduce unnecessary physical exertion, especially in warm/hot environments.
  • Drink water frequently.
  • Use loose-fitting, lightweight clothing.

There are other, similar measures that can be applied as preventive or during incidents. Department safety officers must become familiar with the symptoms of heat stress, how to recognize them, how to prevent heat stress, and how to treat it if it affects any of the department’s personnel, either during in station activities or during interventions.

Author’s Note:The information in this article is based on a document produced in Spain several years ago as a Procedure of Good Practice for the use of PPE by Spanish emergency responders. The document is still used as a reference and a training aid.    


George H. Potter is a practicing fire protection specialist who has lived in Spain for the past 45 years. He served as an Anne Arundel County, Maryland, volunteer firefighter with the Riva Volunteer Fire Department and the Independent Hose Company in Annapolis and as an ambulance driver with the Wheaton (MD) Rescue Squad. He served six years in the United States Air Force as a firefighter, an apparatus driver/operator, and a crew chief. He has been involved in fire protection system installation, mobile fire apparatus design, and construction and fire safety training. He is a Spain-certified fire service instructor and a hazmat specialist, and is a member of the Board of Governors of the Spanish Firefighters‘ Association (ASELF).



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