Heat stress: additional considerations
Eric. S. Lamar
Health and Safety Advocate
Fairfax County (VA) Professional Fire Fighters
IAFF Local 2068
This is in response to “Physiological Responses to Working in Bunker Gear: A Comparative Study” (November 1994). While informative, the article did not address a number of areas of concern when dealing with the problem of heat stress in the fire service. NFPA 1500-compliant turnout clothing provides the wearer with a significantly higher level of protection than 34 boots. Other factors are far more likely to lead to heat stroke and heart attacks on the fireground than the study in the article acknowledges. The study`s design does not take into consideration actual fireground activities and procedures required under NFPA 1500, such as physical rehabilitation.
The study was very pointed in that the majority of physical stress-related heart attacks experienced by firefighters may be solely attributed to wearing NFPA 1500-compliant turnout gear and asserted that the higher level of protection provided by NFPA 1500-complaint gear from burns and other factors present at the fireground is not a reasonable trade-off for the dangers of heat stress…and went on to claim that by wearing 34 boots and a long coat firefighters will be safer at the fireground. These oversights may…give birth to “perceived” dangers associated with wearing NFPA 1500-compliant clothing that are not valid concerns.
The article states that NFPA 1500-compliant gear is the result of “Project FIRES.” This is inaccurate. Project FIRES clearly demonstrated that wearing bunker pants affords a greater level of burn protection over 34 boots based on real fire evolutions and real-world experience through evaluation by professional firefighters throughout the United States. The NFPA standard relating to structural firefighting (NFPA 1971) has evolved in its own pathway, independent of Project FIRES. However, the International Association of Fire Fighters (IAFF) has gladly made Project FIRES` data and information available to the NFPA 1971 subcommittee for its review and evaluation….The NFPA 1971 subcommittee`s decision to require bunker pants was the natural evolution for firefighting protective clothing, as firefighters today must face greater heat and increasingly unstable environments in the workplace. Project data showed that the majority of burns experienced by firefighters occurred to the thigh-buttock and groin regions of the body. As a result of the direction in concept design of turnout clothing pointed out by Project FIRES and acted on by the NFPA 1971 subcommittee in 1988, this situation has changed dramatically. The number of burns to these body areas are no longer the leading areas for injury, and the total of burns experienced in departments wearing NFPA 1500 gear has dropped significantly. A decrease in the severity of those burns has also been demonstrated to be a direct result of wearing NFPA 1500-compliant protective clothing….
The study states that “it is possible that turnout clothing (specifically bunker pants) is more cumbersome and thereby decreased the mechanical efficiency of the individual when performing the task.” Project FIRES reported that “Firefighters found that the leg protection system (bunker pants) provided superior protection from heat, water, steam and embers, while providing greater freedom of motion than standard 34 boots” based on real environment and application evaluations. In addition, the study utilized an 8.5-oz./square yard garment. Project FIRES specifications call for a 7.5 oz./square yard material, and fabrics as light as 6.0 oz./square yard will meet the current NFPA 1971 requirements.
In the professional fire service, burn injury rates and heart/stroke-related injuries have continuously decreased since 1968. This reduction in injury rates may be attributed to the advances made in protective clothing and equipment and their usage–mainly SCBA and improved turnout clothing. If NFPA 1500-compliant turnout clothing was a significant contributing factor in the heat stress experienced by firefighters, we would see an increasing number of heart attack/stroke-related injuries since the inception of NFPA 1500….
Subjects in the study walked on a treadmill at 3.5 km/hr. (2.175 miles/hr.) at a 10- percent grade for 15 minutes, followed by a 10-minute period of passive recovery. The physiological stress data presented in the article are reflective of what they are–the physiological responses of firefighters to a laboratory experiment that does not in any way reflect a “real” fire or training evolution. In an actual fire evolution where (NFPA 1500 is implemented in the department), firefighters are medically monitored before, during, and after an evolution. The monitoring is designed to identify personnel experiencing heat stress. Personnel go through this monitoring process after each air bottle, and they are required to go through a rehabilitation process immediately upon exiting the structure or when their vital signs indicate they may be experiencing the effects of heat stress….These considerations were not discussed in the study.
The article puts an interesting idea forward, and one that needs to be addressed. It states that “It can be argued that most of the deaths due to heart attacks and stroke are related to heat stress and physical exertion….” This is clearly backed up in the NFPA firefighter fatality survey for 1993. The NFPA states that “the number of heart attacks reported in 1993 is the same as the number reported in 1992–again, the lowest in the 17 years we have collected these data.” From this year`s data, as well as from previous years, we can ascertain that there is a definite correlation between heart attacks and physical stress.
What is this stress? We can assume that all firefighters wear protective clothing, so that makes turnout gear a consistent factor throughout the NFPA`s data. Of the 39 heart attack victims in 1993, 16 were known to have had heart problems–either previous heart attacks or bypass surgery, five were known to have had severe atherosclerotic heart disease, and one was a diabetic. One of the most significant factors that must be noted is age. Sixty-four percent of heart attacks were experienced by firefighters over the age of 50, and 84 percent of those heart attacks were experienced by firefighters over the age of 55. The NFPA`s report goes on to state that “37 of the 39 heart attacks were due to stress and overexertion, and the remaining two were from smoke inhalation (carbon monoxide poisoning). Based on these data, we can agree that physical condition plays an important role in determining the amount of physical stress a firefighter can take before experiencing a heart attack, not to mention that many people have a genetic predisposition toward heart disease.
There is a significant correlation between personnel levels and overexertion. The Austin Fire Department Staffing Study (March 1993) and others have found there is a direct correlation between staffing levels and cardiovascular stress levels….
One would have to agree that the burn and chemical protection provided by NFPA 1500-compliant turnout clothing exceeds the limited contribution to heat stress that it may add to the firefighter while at the fireground. The level of protection provided by NFPA 1500-compliant turnout clothing is required in today`s fire environment…. The most important factors to consider when attempting to reduce fireground heart attacks are the age and physical condition of personnel and the staffing levels present at the fireground….
