Personal Protective Equipment (PPE): equipment intended to be worn or carried by personnel working in proximity to a perceived hazard and designed to mitigate or prevent injury in the event of contact.
Originally, in the days of horse power and steam pumps, PPE was intended to protect fire fighters and their draft animals from severe cold, water spray, especially in freezing weather, and, to some extent, radiant heat. In those early days it was common practice to either unhitch the teams and remove them out of harm’s way (and in the process leaving the apparatus without means of movement) or to cover the animals with blankets to protect them from the extreme cold and ice as well as flying embers.
PPE that protected the firefighters was usually a long coat made of rubberized fabric, hip boots and the traditional billed helmet. This ensemble worked fairly well in its day. The helmet could be worn with the bill to the back to prevent water from running down the wearer’s collar or it could be turned around to afford the wearer’s face some protection against radiant heat. The rubber coat kept the wearer relatively dry and to some extent warm, in cold weather and parboiled him in the heat of summer.
That was about it so far as PPE was concerned. Bear in mind that in the horse drawn era coal was king. Hazardous materials, as we define them, were almost unknown save for the barrel of kerosene in the general store used for illumination and, in some cases, cooking. To be sure there were a few installations that contained relatively significant quantities of hazardous or flammable materials such as the local pharmacy and oil refineries (after the discovery of petroleum in 1859) established for the production of kerosene. Various chemical processes such as metallurgy, leather tanning and precious metal recovery were part of the industrial community but these were few in number, relatively small in size and the plants where they were utilized were usually isolated remotely and safely away from centers of population.
Hence, the usual municipal fire department had little, if any, contact with these materials. Coal, of course could become hazardous to some extent if piles became wet, especially if these were contained within a confined space but such incidents could be controlled, usually by dispersing the coal and extinguishing fires with water applied in deluge quantities.
Thus the PPE in the armamentarium of the average Fire Department was minimal, almost to the point of being non existent.
As industrialization of America began to advance during the 19th and early 20th centuries more and more of the “better things for better living through chemistry” became reality. The extent of the hazards inherent in the pursuit of these operations became increasingly obvious and the need to protect firefighters and other emergency response personnel from these hazards rose to preeminence. It can certainly be argued that the need for, and the subsequent development of PPE was a direct result of industrial development and the population growth of the country.
America has always been a nation on the move. We seem have an inborn need to see what’s over the next hill, whether it be on the next block or half a continent away. As a result, America became, in the early 19th century the world leader in rail transportation and this transportation was powered by the steam engine fueled by “King” Coal. “King Coal” does his work well but in the process he produces prodigious quantities of smoke and noxious gasses.
As cities expanded and the need for access to transportation became more and more acute tunnels were constructed in New York and other cities to allow trains to run underground and emerge in the centrally located station. Tunnels were also utilized in mountainous regions to get trains across otherwise impassible ranges. This worked fine so far as the trains were concerned but the engine crews were another matter entirely. The build up of smoke and fumes from the engine exhaust was devastating. Crews were sickened and there are reports of crewmen occasionally losing consciousness due to the effects of the toxic atmosphere.
As usual in such instances necessity was the mother of invention. Numerous schemes put forth to provide a breathable atmosphere for the trainmen. One involved having the engine crew don a mask which was connected to the air-brake system on the engine. This, it was thought, would provide relatively clean air to the train crew while they were in the tunnel since the reservoir would have been filled up outside the tunnel. A great idea if it had worked but the proponents didn’t realize that the compressors that powered the air-brake system were oil lubricated. The air that went to the trainmen was no better (if not worse) than the atmosphere of the tunnel from which they were seeking protection. The idea was sound but the equipment was not up to the task. The problem continued to plague the railroads until the advent of electric locomotives with power enough to move long trains through tunnels and subways. Today, engine crews operating through the long tunnels in the western Rockies are issued SCBA for use in case of emergency.
As America’s industrial capacity and infrastructure grew the need for energy increased and this meant an increase in coal mining activity. Coal mines went ever deeper the danger of caveins and other accidents increased as did the risk of “fire damp” or carbon monoxide (CO), methane (CH4 ). This increased risk brought about the advent of SCBA in coal (and some other) mines. As the 20th century progressed, petroleum supplanted coal as the fuel of choice in many applications and gave birth to the petrochemical industry and its myriad products and intermediates, many of which were in fact hazardous.
As industrial complexes increased in size, complexity and content, emergency responders were forced to recognize hazards these installations provoke and take measures to protect personnel and the local population.
Providing adequate PPE for an emergency response organization can be, and often is, much more difficult than providing it for operating personnel in a plant or storage facility. In the plant we are fortunate in knowing what is present. If it is flammable we protect against fire. If it is caustic we protect against contact. If it is a toxic gas we are pre-warned and know what PPE is needed. Not so with the emergency responders. When the bell rings they go and they may not know what awaits them until they arrive; even if it is their company’s truck or railcar that is involved. They may know what product was shipped but they don’t necessarily know what side reactions may have occurred. For example: the large cloud of carbon dioxide (CO2 ) that will likely be present if that overturned tank of hydrochloric acid (HCL) begins to leak onto a roadbed ballasted with crushed limestone(CaCO3 ). Or the dense cloud of ammonium Nitrate (NH4 CL) that may result if a car load of anhydrous ammonia (NH3 ) leaks into the cloud of (HCL). There is also that nice orange cloud of oxides of nitrogen that shows us that nitric acid (HNO3 ) has reacted with a red Metal (copper and/or brass fittings commonly). The list goes on and the emergency responder must be ready to deal with any of them. Thus PPE has evolved in response to evolving needs, from a bunch of “one size fits all slickers” hung on a hook over the tailboard of the fire engine to a veritable wardrobe of specialized garments and accessory equipment which may occupy a major portion of the response vehicle. Such is the price of “progress”. Personal protection is always a trade off. Surgeons wears rubber gloves to prevent the transfer of infection but in the process lose some touch sensitivity. The “Class A” encapsulating suit is very effective when used to protect personnel from a noxious atmosphere while affecting mobility, increasing the weight carried by the operator and a reduction in the working time due to the need to change air tanks. Very often, there is an increase in the metabolic load imposed by the increased weight and the higher environmental temperature and humidity encountered in the suit. So, protection, while absolutely necessary, is obtained at a cost and this cost is not measured in monetary terms but, rather, in terms of increased stress and reduced working times.
In order to adequately protect response personnel from inherent hazards it is necessary to know we are trying to protect against. Enter the art of monitoring and detection. This phase of PPE also has evolved. In the early days of coal mining in Cornwall it was common for miners to take canaries into the pits with them. This alerts workers to the presence of a toxic atmosphere. Being sensitive to a dangerous environment, canaries would stop singing, appear lethargic and even expire before the poisonous atmosphere incapacitated the miners and thus gave them a chance of escape. From this crude beginning monitoring instrumentation, like other sub-sets of PPE, evolved into very sophisticated “lab in a box” instrumentation commonplace in today’s emergency response protocols. The evolutionary process carries with it the need for extensive training as well as the physical cost of adding more equipment on the operator. Therefore it behooves those in charge of emergency response operations to try to strike a balance between providing protection, the physiological cost and the technical limitations of carrying out monitoring protocols.
Monitoring and detection equipment is, usually, expensive, both to purchase and to maintain. It suffers, all too often, from the “out of sight out of mind” thought pattern and this can be disastrous at the scene of an incident. Early day canaries required care every day; thus the caretaker would notice any that were sick or otherwise unfit for use. Not so with today’s electronic marvels. These can be (and, unfortunately, too often are) set on the shelf for weeks on end and forgotten about. Then the bell rings we wonder why they don’t work. Monitoring instruments should be checked out on a regular and fairly frequent schedule. They should be stored with the batteries removed to prevent damage from corrosion This can occur in spite of the claims of battery manufacturers. A spare set of fresh batteries should always be available and should be exchanged regularly. Components, such as chemical based detection cells, having a shelf life should be checked for adequate activity and a replacement component (in a factory sealed container) should be available. This is particularly true in the case of instruments located in more arid regions. Instrumentation is not, in the usual course of events, an “off-the-shelf ” item; so, order ahead in anticipation of future need. Thismeans that there will be some waste and this is generally unavoidable. A chemical cell will dry out whether it is used or not. When it does it must be replaced.
This leads to another admonition. Do not be afraid to utilize instruments for training. The detector cells will dry out whether the instrument is used frequently or is set unattended on the store room shelf. If the instrument is used in training exercises any sign of malfunction or expiration of components will, or should, be noticed and corrective measures undertaken immediately.
Calibration is another area which often suffers from neglect. In some cases absolute calibration is less important than it is in others. If an instrument tells me that hydrogen cyanide (HCN) is present I’m going to don full protective gear in the event that I absolutely have to enter. This is a case of any being too much. On the other hand, there are instances which may result in litigation. Actual concentration values are important. It behooves the prudent responder to make sure instruments are calibrated in a timely fashion and by a method approved by the manufacturer. Recalibration should be done after each use especially if the instrument has encountered a high concentration of the contaminant.
Know what your instrument is telling you. I attended a training exercise held on a simulated ocean tanker. One of the hatches had been rigged with a blind pipe which had a piece of “dry” ice in the bottom to simulate an anoxic atmosphere. The trainees were using a Davy Safety Lamp. They lower this instrument into the blind pipe to get an indication of the condition of the atmosphere in the tank, which was supposed to be empty or nearly so. A “salty” veteran chief petty officer went up to the hatch, lighted the safety lamp, adjusted the flame to the witness marks and lowered it into the blind pipe. After a few seconds he pulled up the lamp to find that the flame had gone out. He muttered a few words concerning the quality of the equipment and relighted the flame. Again when he pulled out the lamp the flame was out. At this point our CPO said a few words that Mother would not have approved and sent a seaman down to get one that worked. This second lamp also had a flame out and by this time the Chief was livid. The instructor stepped in to and explain that the lamp was indeed functioning as advertised. It told the Chief that the atmosphere in the tank (blind pipe) would not burn; it did not say why it would not burn. The truth was that the flame went out because there was no oxygen to support combustion. Had this been a real tank the fumes would have displaced the air (oxygen) and there would have been no fire or explosion. However when the hatch was opened interchange between the tank and the atmosphere took place and in all probability, the atmosphere would test flammable.
Bottom line, the lamp was telling the Chief that the atmosphere as it existed at the moment was not flammable. It would not burn but the lamp was making no statement about why it wouldn’t burn or what the combustible component might be. All we know for sure is that the atmosphere is not flammable.
A similar situation can exist in the case of the MSA model 2a Explosimeter. This instrument has has rendered yeoman service to the emergency response community, still it is not fool proof. It is calibrated in terms of the LEL (Lower Explosive Limit) of methane (usually, though other calibrating agents may be used for special circumstances) not absolute concentration. An experienced “meter man may test an area and report a reading of “100 and twenty-five”. This doesn’t mean 125 percent of the LEL. It means that as the probe was introduced into the test atmosphere the needle went all the way over to 100 percent and then fell back to 25 percent. What actually happened was that the level of the contaminant was above the LEL and, because of the lack of oxygen the instrument read 25 percent LEL. However as the responder moved around and the entrance was opened, air would be admitted and the atmosphere would test as being flammable. What the operator is trying to communicate is the fact that the meter read 100% and then fell back to 25%, which would indicate a very rich atmosphere indeed rather than starting at 0 and going up to 25% which would indicate an atmosphere well below the LEL and would be relatively safe to enter. Bottom line; know your instrument. How it works and understanding what it is telling you is much more important than knowing which buttons to push to make the lights blink and the hands move. Monitoring and detection has, arguably, evolved more than any other branch of Emergency Response protocol. It began with the canary bird and progressed to the sophisticated “lab in a box” which can be carried easily in one hand and that can deliver accurate results within seconds. Evolution in technology does not guarantee concurrency in the ability of the operator and it is only prudent that those responsible for monitoring an incident site be specially trained for this most important task. It is imperative that this training include actual “hands on” experience with the instrumentation that is expected to be deployed at an actual incident but by no means should the theoretical knowledge requisite to effective monitoring.
Finally one must consider the material from which PPE is constructed. Here again we see a profound instance of evolution. The original rubbberized fabric from which the early slickers and boots were fabricated served its purpose well. It kept the wearer dry, for the most part, and helped to keep him/her warm during cold weather; comfort during the heat of summer was another matter, however. As the petro-chemical industry matured a wider variety of materials was encountered and many of these could degrade and/or penetrate the rubber coats. Thus, evolution in the number of exposure agents necessitated a concurrent evolution in the materials utilized in the construction of PPE. The problem is exacerbated when the responder is confronted by multiple hazards. He may, for example need to be protected from a polar solvent and perhaps toxic fumes. A Class A protective suit with, of course, SCBA would seem to be appropriate protection but wait a minute. If there is fire involved wouldn’t there be a risk of an ember burning a hole in the suit? What is the non polar solvent? Will it degrade the material of the Class A suit? There is no universally resistant suit material. All of them will react with something. This leads to the practice of wearing multiple garments, each offering protection from a specific hazard. The problem is that with each additional garment comes a restriction in movement, additional weight and increased physiological stress.
Another problem with protective clothing is that of decontamination. In the main, the answer to this problem is to deploy single use or “disposable” garments. This leads to the need for a large inventory of suits to enable crews to respond to incidents involving a multiplicity of commodities.
Protective clothing as we know it has a definite shelf life. This means it will be necessary to discard outdated items. This is a good way to get clothing for training purposes.
Read the “fine print” to discover that most hazardous materials will eventually break through any of the commonly used suit materials. This “breakthrough time’ can be important. If the breakthrough time for “tri-methyl-badstuff ” is 12 hours it is a good idea to change clothes after about ten hours.