Sometime in the primordial past primitive man discovered fire and concurrently the fact that it could cause him injury. He also discovered that certain rather elementary precautions could, if taken or observed, protect him from harm. So, when that first caveman figured out that wrapping a bit of animal skin around the end of a hot object would keep his fingers from being burned, personal protective equipment was born. The procedure has changed little from the day of the caveman to the present as any homemaker demonstrates when she grabs a couple of "potholders" to insulate her hands as she removes the Christmas turkey from the oven.
During the early days of the twentieth century my maternal grandfather was a railroad boilermaker. He used to tell me how, when he and his crew needed to enter a hot firebox, they dressed in a number of layers of long underwear. As a young child this practice really did not make sense to me. One normally wore long underwear in the winter to keep warm. In a boiler Grandpa was already warm; why the "long-handles?" Wouldn't that just make the situation worse? It was only after the principle of insulation to prevent heat transfer had been explained to me that I began to understand. Ice blocks were buried in sawdust to keep heat out, not to keep cold in. Grandpa wore long-handles in the wintertime to keep the heat in and then wore them again in a boiler to keep it out. Early day firefighters encountered similar problems when they attempted to approach close enough to a conflagration to apply effective suppressive measures. Necessity is the mother of invention. The firefighter's need for thermal protection led, eventually, to the development of specialized protective clothing which eventually evolved into modern turnout gear.
The two most obvious hazards from which firefighters need to be protected are smoke and heat. Breathing apparatus should take care of the smoke and heavy, fire resistant or retardant clothing should provide thermal protection. One would think that the problem was now solved but this is a gross over-simplification. One dousing with water and the insulative properties of the protective garment are gone. If the water is hot from contact with the fire or objects involved in the fire, scalds can result. If it is cold, freezing or frost bite could be a potential hazard. In either case, the comfort and effectiveness of the firefighter is compromised. One answer to this problem has been to incorporate a covering of waterproof material known as the "vapor barrier" into the protective garment. This layer kept the wearer dry and the insulative properties of the garment in tact. Again it was thought that the problems with protective clothing were solved.
However, the "law of unintended consequences" intervened and the solution to one problem became the genesis of another. Since no one has yet developed a practical "one way" fabric, vapor barriers work in both directions, in and out. By limiting contact with the atmosphere they retard the cooling effect of perspiration and thus increase the risk of overheating and the effects of heat exhaustion or heat stroke.
There is also the possibility of a firefighter being enveloped in a cloud of steam or hazardous vapor (toxic, corrosive or flammable) which could rise under the skirt of a turnout coat, making the garment into a trap which actually works against the purpose for which it was originally designed. This hazard was one of the factors considered in the decision to eliminate the traditional long coats and high boots as meeting the standard for personal protective clothing even though these garments were very convenient, especially for volunteers or off-duty personnel who often had to quickly don turnout gear at the scene of a fire. The possibility of vapor incursion has also led to the practice by some hazmat responders of sealing pant legs, coat sleeves and waistband with duct tape. While not something that one would recommend as "best practice," this technique can in some instances be effective.
While turnouts or bunker gear have been around in some form almost as long as there have been firefighters, they are not a panacea for all of the hazards that an emergency responder is likely to encounter; particularly those associated with hazardous chemicals. These materials are hazardous because of their chemical properties, not their physical characteristics. Therefore the only effective method of protecting those engaged in hazmat emergency response is to prevent contacting the hazardous substance. Depending upon the nature of the material in question, this may mean nothing more than wearing an air purifying respirator (APR) or it may mean a positive pressure Self Contained Breathing Apparatus (SCBA) worn under a sealed, totally encapsulating positive pressure suit which, in turn, may be covered by some sort of work garment to prevent a breach in the integrity of the suit due to burns, tears, abrasions or punctures. The variety of materials from which these protective garments are made is as diverse as the materials from which they offer protection, and there simply is no such thing as "one size fits all." Therefore the task of selecting the most effective suit material to use for a particular incident can become daunting.
In the first place, it is of the utmost importance that the identity of the material be known. Unfortunately this is not always possible in an emergency response situation, and there is always the possibility that a reaction between two or more materials may result in the creation of a third, heretofore unknown, entity. For example, consider a train derailment involving a car containing hydrogen chloride (HCl) and another loaded with anhydrous ammonia (NH3), both are gasses and would, if their containers were breached, combine to produce a third compound, ammonium chloride (NH4Cl), which is a very soluble white solid. In the presence of water, HCl dissolves and dissociates to form hydrochloric acid (sometimes known in the trade as muriatic acid), and NHdissolves in water to form a solution of ammonium hydroxide (NH4OH), a base.
Thus we must contend with four components in the derailment instead of the original two, and the difference in state (NHand HCl are gasses under ordinary conditions, NH4Cl is a solid, hydrochloric acid is a liquid and NH4OH exists only in an aqueous solution) adds to the difficulty of selecting appropriate protective clothing. HCl (in aqueous solution) is a strong (very highly ionized) acid. NH4OH, in solution, is a moderately strong base and NH4Cl is a particulate, thus responders must be protected from all three hazards.
In rookie school, fledgling student firefighters are constantly admonished to don their turnout gear before actual fire fighting. There can be no question that this is usually a good and wise practice - especially in the case of common structure fires - but there are exceptions.
Ordinary turnout gear is designed to repel water and other polar liquids. Should it come in contact with non-polar materials such as fuels, other petroleum products or coal tar derivatives such as benzene, these can be absorbed into the fabric and actually increase the danger to the wearer, especially if the contaminating substances are flammable or combustible.
This is also true of various poisonous substances, some of which may even linger in the fabric of the turnout gear after use and require that the contaminated garment be thoroughly cleaned or replaced, lest they pose an additional danger of re-exposure to the next wearer or spreading contamination to the surrounding environment.
Response personnel must be made fully aware of these dangers and be prepared to remove contaminated turnout gear immediately in the event that such contamination does occur. They should be vigilant in recognizing signs of a reaction between various commodities present at an incident. They should certainly know where and how to find all available information as to the identity of all materials present in an incident, but when they pull up to a burning eighteen wheeler on the side of the highway thirty miles from the nearest town they may have nothing to go on but their own eyes. Manifests and bills of lading may not be available, the driver may not be able to talk and the nearest dispatcher or other knowledgeable party may be hundreds of miles away. In the case of an independent trucker, he might be the only person who knows what is on that truck, and he may not be able, or willing, to communicate. These are the cases that keep hazmat responders awake at night. When push comes to shove in cases like these the best course of action is often to rescue, if possible, any persons trapped in the vehicle, evacuate anyone in harm's way? and then let the situation stabilize itself. There probably would not be much, if anything to salvage anyway.
Of course, if the responders have credible knowledge of the materials involved and the equipment and expertise to attempt to remediate the incident, by all means they should do so. But in the absence of knowing the risks, they all too often out weigh any possible gains. After all, if you do not know what you are dealing with, how do you know what hazards you should be protecting against and what sort of protective equipment will be effective against it?
Protective headgear is another factor that must be considered. The traditional firefighter's helmet is one of the best pieces of equipment available for the prevention of head injuries. The long bill can prevent injuries from burning embers or streams of water going down the back under the turnout coat; turned around, it can shield the wearer's face from much of the heat and/or steam encountered in a close attack.
The traditional leather used in the construction of these helmets, as well as more modern composite materials, is an electrical insulator and can protect against electrical shock from dangling overhead wires, particularly in a structure fire. The devices also protect against injuries caused by blows from falling objects, low door jambs or other pathway obstructions that may escape notice under fire ground conditions.
Unfortunately encapsulating suits do not usually accommodate the traditional firefighter's helmet, but head protection must never be ignored and any such equipment must be equipped with an alternate helmet to protect the wearer from head injuries. The typical construction worker's headgear is usually a good compromise but only those made of non-conducting material and containing a separate suspension harness should be considered. We have a trade-off - the advantages of the firefighter's helmet versus an encapsulated hazmat suit.
The main point to be considered in the selection of personal protective equipment for emergency response personnel is what are we trying to protect against? If it is thermal injury, then the traditional turnout gear is certainly the best choice. If an inhalation hazard is in the mix, respiratory protection is mandatory. If chemicals or other hazardous materials are involved, then appropriate protective gear must be added.
While any and all possible hazards need to be considered in the selection of protective equipment, the risks involved need to be considered along with the possible consequences. Encasing a firefighter in turnout gear to protect against thermal injury, adding self contained breathing apparatus (SCBA) to protect against inhalation hazards, following up with an encapsulating suit complete with specialized boots and two or three layers of gloves to prevent chemical exposure, and adding the necessary tools and equipment requisite to the task at hand will, at some point, overload him so that he cannot even walk to the fire ground, let alone accomplish any meaningful work. We have to make choices.
If there is no fire and no likelihood of any, eliminate the turnout gear. If the chemicals present are not ones that can be absorbed through the skin, omit the encapsulating suit. If there is an adequate supply of oxygen and the identity of the air contaminant is known, replace the SCBA with an Air Purifying Respirator (APR).
All of these factors enter into what we finally decide upon as adequate personal protection for a particular situation. We need to provide adequate protection against whatever hazards exist, but anything extra adds weight and impairs vision, movement and balance, increasing the chances of injury. We must not enhance the chance of one type of injury by protecting from another.