Now that we have addressed the new title, let us now take a look at two topics — the first being the concept of getting “back to the basics” of hazmat and the second being an emerging threat in hazmat that bears discussion for all levels of hazmat responders, and emergency response personnel in general.
In the emergency services arena, there exists a continual cycle of branching into new areas or embodying new response techniques and/or equipment leading to a cry of “We need to get back to the basics!” While I personally advocate the employment of the latest and greatest high-technology equipment for hazardous materials response (e.g. polymerase chain reaction (PCR) technology, the use of infra-red technology to perform stand-off sampling, electronic hazmat research software, etc.), I also believe that we should not forget “from whence we came” in terms of the continual honing of our basic hazmat response skills.
One area in which we can get back to the basics is by revisiting the foundation of our air monitoring efforts — the four-gas meter in general, and specifically the oxygen sensor therein. Our standard four-gas meter allows us to measure toxicity in terms of carbon monoxide (CO) and hydrogen sulfide (H2S) concentrations in parts per million (ppm). In addition, we can monitor for flammability in terms of the percentage of the lower explosive limit (% LEL). We do have to remember, however, that the combustible gas indicator (CGI) sensor utilized to monitor for flammability exhibits relative response — meaning if you are monitoring for any gas or vapor different than that which the CGI sensor is calibrated to, the user will need to multiply the meter units displayed on the CGI sensor by the appropriate relative response correction factor provided by the manufacturer.
If the four-gas meter is the foundation of our air monitoring efforts, the fourth sensor — the oxygen (O2) sensor — can be thought of as the keystone of that foundation. As one of the founding fathers of hazmat response in the Southeastern U.S. — the late Capt. Shelton T. Eudy — would regularly state, “Give me a meter with an O2 sensor and I can work almost any hazmat call.”
Our O2 sensor will not only enable us to determine if we have an oxygen deficient (less than 19.5 percent O2) or oxygen enriched (greater than 23.5 percent O2) atmosphere, it will also allow us to determine the relative concentration of a contaminant or contaminants by noting the level of oxygen displacement. A detailed description of such calculations can be found in the previous Carolina Fire Rescue EMS Journal article “From Damage Control to MacGyver — Hazmat Tricks of the Trade.”
Another area in which we can get back to the basics is through the use of chemical classification systems that are not high-technology in nature, but are proven and reliable. An example of this type of equipment is the HazCat® chemical classification system. Such systems allow users to classify chemical samples through the employment of specific tests at specified points of a flow chart.
By following the proper flow chart, hazmat responders can proceed through a process of deductive reasoning to determine the product or products involved, or at least narrow down the possible product or products present. Such classifications are independent of external infrastructure needs such as electrical power or internet access.
An additional “tried and true” piece of equipment that is of a basic nature is the coliwasa tube utilized for liquid product sampling. “Coliwasa” stands for COmposite LIquid WAste SAmpling, and refers to a tube that usually has an internal rod running the length of the tube (and projecting a distance from each end) with tapered stoppers on the top and bottom. To collect a sample, the stopper at the top end is slid up the rod to allow the rod to be depressed. The rod is then depressed to open the bottom orifice of the tube and the tube is inserted into a liquid column. The rod is raised to trap the liquid inside the tube, and the tube is then withdrawn from the liquid column. The liquid sample can then be transferred to smaller containers, and stratified samples can also be segregated.
In terms of air monitoring, a “back to the basics” type of equipment that can be utilized in a qualitative and quantitative manner to detect and measure the concentration of gases or vapors is the colorimetric tube sampler. Although multiple manufacturers make such air monitoring equipment, the basic operational characteristics remain the same. The colorimetric tube itself is product-specific and consists of a glass tube containing a reagent that will change color in a specified manner when exposed to the target gas or vapor. The glass tube is also normally provided with a graduated scale, in which the color change of the reagent indicates the concentration of the target product.
A hand pump (either bellows or piston type) containing a counter system that indicates the total number of pump strokes is provided to draw atmospheric samples through the tube. To use a colorimetric tube sampler, the ends of the glass tube are broken off, the tube is inserted into the hand pump, and the hand pump is activated a given number of times as per the manufacturer’s instructions for the specified tube.
The color change (again as per the instructions for the specified tube) is then viewed, denoting the presence of the target product and the concentration of said product. The colorimetric tube sampler operates — like the chemical classification systems previously discussed — independently of external infrastructure needs.
The final “back to the basics” pieces of equipment that we will discuss are hard-copy hazmat research resources. While there are many excellent electronic hazmat research programs and databases that can either be downloaded for free or purchased from various vendors and that can greatly enhance our research capabilities, hazmat responders need to retain the hard-copy resources and the prerequisite skills to utilize them in case research computers go off-line, batteries run out in the field, etc. Such resources may include the NIOSH Pocket Guide, Hawley’s Condensed Chemical Dictionary, The Handbook of Compressed Gases, hazmat personal protective equipment compatibility data, and others.
In summation of the “back to the basics” approach to hazardous materials response, I am not suggesting that we turn our backs on the high-technology equipment available to us, but that we simply retain our skills and abilities in the utilization of equipment that is known to reliably perform and oftentimes requires no external infrastructure support. Such equipment and the related techniques utilized should serve as tools to choose from in our “hazmat toolbox.”
We will now briefly touch on an emerging threat for hazmat responders (and emergency responders in general). There have been two recent incidents in which leaks from cryogenic carbon dioxide systems in fast-food restaurants have led to injuries and even a fatality.
For many years, carbon dioxide stored as a compressed gas has been used in beverage dispensing systems. Recently, the prevalence of storing carbon dioxide as a cryogenic (gas liquefied through cooling) for beverage dispensing has greatly increased due to the efficiency and capacity of such systems.
As we know, carbon dioxide displaces oxygen and a carbon dioxide leak can result in an oxygen deficient atmosphere. One of the two aforementioned incidents occurred in Phoenix, Arizona, where a call to a local fast-food restaurant to a worker that had fallen in the basement resulted in a full hazmat dispatch to a carbon dioxide leak in a cryogenic system. During the response, two fire department personnel also presented symptoms of exposure to an oxygen deficient atmosphere.
The second recent incident underscoring the hazards of a carbon dioxide leak in a cryogenic system occurred in Pooler, Georgia. A patron of a fast-food restaurant entered the restroom of the restaurant and unknowingly entered an oxygen deficient environment due to a carbon dioxide leak in a line closely proximate to the restroom, resulting in the death of the patron.
The lessons learned from the two incidents include the fact that fast-food restaurants may contain basements, that responders should always be cognizant of the mechanism of injury presented on a medical call and the possibility of a hazardous environment existing therein, and that (in the Phoenix incident) some combustible gas indicators may exhibit a cross-sensitivity to carbon dioxide. Phoenix Fire Department responders encountered a reading approaching 100 percent LEL when in reality the environment was not flammable.
In short, we should remain aware of the prevalence of carbon dioxide in cryogenic storage in our response territory, its hazards, and the need for noting the existence of such systems in our pre-planning activities. A “lessons learned” report on the Phoenix incident can be found at: http://phoenix.gov/webcms/groups/internet/@inter/@dept/@fire/documents/web_content/065464.pdf
As always, be safe out there and be sure to visit the North Carolina Association of Hazardous Materials Responders’ Website at www.nchazmat.com.
Glenn Clapp is President of the North Carolina Association of Hazardous Materials Responders and is a Fire Training Commander (Special Operations) for the High Point Fire Department. He is a Technician-Level Hazmat Instructor, a Law Enforcement Hazmat Instructor, and is a Certified Hazardous Materials Manager and Certified Fire Protection Specialist.