In a practical sense, what is decontamination — often referred to as decon? While many civilians and even emergency response personnel view decon as the complete removal of a contaminant or contaminants from persons or objects, decon can more properly be viewed as product reduction. Product reduction refers to the reduction in the amount of contamination present to an acceptable level. The actual process of decontamination can take several different forms.
Dry decontamination may be performed by brushing any contamination off of the surface of the object being deconned — oftentimes utilized when the contaminant is a water-reactive substance — or even simply by carefully rolling contaminated PPE downwards upon itself and discarding it in a proper container for disposal. This is often seen in laboratory settings when dealing with limited quantities of contaminants at relatively low toxicological levels.
Absorbent materials can also be used in the decontamination arena to “soak up” contaminants, as can adsorbent materials. The major difference between the two similar-sounding methods is that an absorbent material increases in volume in its interaction with the material being absorbed, while an adsorbent material does not increase in volume in the chemical-adsorbent interaction.
Think of an absorbent sponge that has soaked up a liquid, then no matter to what extent it is wrung out some amount of the liquid remains trapped in the sponge. With an adsorbent, the liquid can be completely extracted from the sorbent.
Additional decontamination processes consist of:
- Chemical degradation — the natural breakdown of a contaminant
- Evaporation — natural degradation through the vaporization of a contaminant
- Dilution — the reduction in concentration of a contaminant through the application of a substance such as water
- Disposal — directly removing a contaminant
- Neutralization — reducing the level of harm of a contaminant through a chemical reaction)
- Solidification — converting a liquid to a more easily disposed of solid,
- Vacuuming of a contaminant into a container.
The most often utilized process, however, is that of washing the contaminant off of the surface being deconned with water — if the contaminant is water-soluble — or water and detergent — if the contaminant is not water-soluble — to lift the contaminant off the surface being deconned, allowing it to be rinsed away. In instances involving a biological contaminant, bleach may be utilized as a decon agent in the proper concentration.
Many hazardous materials responders often inquire as to what level of training is required of personnel performing decontamination efforts. While it would be tremendous if we could train all personnel performing decon actions to the Technician level, the reality of the matter is that hazardous materials responses of magnitude are personnel-intensive operations in which we must augment our Technician-level resources with Operations-level personnel in areas of performance where such actions are practically and statutorily feasible.
As a “Group” in the ICS scheme of things, decontamination efforts are led by a Decon Group Supervisor, who should be certified to the Technician level. Operations level personnel can, however, be utilized to perform decon activities if properly trained in decon measures and in the proper use of PPE utilized. The preceding theory is exemplified in the revision of the Hazardous Materials Operations level certification program by the North Carolina Fire and Rescue Commission to reflect the recent changes in NFPA 472, in that one of the mission-specific competency areas in which Operations level personnel can gain certification is mass and technical decontamination.
I have encountered examples of such joint efforts in which Operations level responders performed decon actions on multiple occasions; however one example stands out above the rest, if nothing else but for the timing factor.
The particular incident involved a response to a chlorine leak at a municipal facility by a Technician level hazmat team within the county to assist the fire department having jurisdiction, whose personnel were trained to the Operations level. It just so happened that the same hazmat team had provided training to the local responders in their decontamination procedures the night before, so at the scene those same responders were called upon to help staff Decon Group positions in order to free up Technician level responders for other needed tasks. Decon operations were performed seamlessly that day, as the old piece of firehouse logic states — if you train in a certain topical area or on a new piece of equipment, one of the next calls will usually involve just that.
Now on to PPE, in terms of what level of PPE should be utilized by Decon Group personnel. The choice of PPE should be made by the Decon Group Supervisor, in concert with the Hazmat Branch Director, Safety Officer (or Assistant Safety Officer for Hazmat if applicable), and the Research Group Supervisor. The rule of thumb for decon of emergency responders exiting a hot zone is that Decon Group personnel may utilize PPE of one level lower than that used by the Entry Group. This is not to say that Decon Group personnel should reduce their PPE selection by one level, but that simply it is an option.
If the Entry Group is wearing Level A chemical protective clothing ensembles (vapor-protective suit with SCBA), then the Decon Group Supervisor may stipulate that Decon Group personnel wear Level B chemical protective clothing (splash-protective suit with SCBA) if the contaminant is not highly persistent, does not present a great vapor hazard, and the use of Level B PPE is consistent with contaminant concentrations and conditions in the Decon Area. If the contaminant in the above example does, however, present a vapor hazard or conditions warrant, the Decon Group Supervisor can require Decon Group personnel to wear Level A PPE.
In such circumstances, we need to remember the tenets of risk-based response, in that Decon Group personnel should wear the level off PPE that provides an acceptable level of protection for the contaminant or contaminants encountered while not physically overtaxing personnel. The use of Level C PPE (splash-protective suit with an air purifying respirator [APR] or powered air purifying respirator [PAPR]) is often overlooked by hazmat teams when conditions warrant, as we are so accustomed as firefighters to using SCBAs on an almost daily basis, while it has been proven by personnel in hospital settings that APRs or PAPRs can be a viable choice of respiratory protection that will be less taxing upon the wearer than SCBA’s.
In incidents involving the technical or mass decontamination of civilians, the hazards presented by the contaminant or contaminants will dictate the level of PPE needed for personnel performing decon measures.
As we are taught from the genesis of our hazmat training, decon operations should be located in the warm zone, or area linking the hot zone (area of contamination) with the cold zone (area of no contamination). Several factors may influence our choice of Decon Area location.
Terrain is one such factor, as we should locate the Decon Area so that the terrain slopes downwards toward the hot zone (if any slope exists) so that any runoff not captured will drain back toward the hot zone. Likewise, wind can be a factor in the location of the Decon Area. When setting up decon measures, any wind present should be blowing down the axis of the Decon Area towards the hot zone so that any contamination will be blown back towards the area of contamination.
As we all know, perfect conditions seldom exist at incident scenes, as sometimes the wind and terrain will be “working in opposition” towards each other, necessitating a judgment call by the Decon Group Supervisor and others in charge. We also should pay close attention to not only the current conditions, but also the forecasted conditions to avoid being surprised by sudden wind shifts. In addition, the Decon Area should be established at a location that (ideally) is close to a reliable water source.
Let us now take a look at the four general types of decontamination setups. Although the terminology may differ from location to location, these categories are:
- Emergency Responder Decon
- Technical Responder Decon
- Emergency Mass Decon
- Technical Mass Decon
We will first examine the category of emergency responder decon. In any instance in which we are sending personnel into an area of contamination or suspected contamination, some form of decontamination should be in place so that we can rapidly decontaminate personnel that may have to quickly exit the hot zone due to equipment malfunctions, changes in incident conditions, etc. In the early phases of an incident, emergency responder decon can be as simple as pulling a booster line — or any other appropriate hose line — off of an engine and placing a collapsible catch basin on the ground to catch runoff.
And speaking of runoff, should we be concerned with the by-products of decontamination? The Environmental Protection Agency takes the stance that the runoff from decon operations should not be neglected, but in the same vain life safety should not be hampered by runoff containment efforts.
The second category of decontamination-technical responder decon-is the type of decon most familiar to hazmat teams. While emergency responder decon is set up as a stopgap measure to allow personnel to enter the hot zone, technical responder decon is just that — a more technical, in-depth set-up to perform decon on emergency responders (and even small numbers of civilians) exiting the hot zone. As for the physical layout of technical responder decon, there are about as many iterations as there are hazmat teams. Some teams prefer to use commercially available catch basins and even entire decon set-ups, while other teams utilize plastic kids’ play pools (a relatively inexpensive option often seen in the 1980s and early 1990s), and still others utilize a large sheet of durable plastic rolled out on the ground, with interlocking pieces of lumber assembled on top of the plastic to form squares and the plastic then folded over the top of the aforementioned squares to form decon pools.
While the actual layout of technical responder decon may change, the sequence of events is very similar. Traffic cones are utilized to guide responders in, where they will encounter a tool and equipment drop. The responders will then proceed to a gross rinse area, where the gross contamination will be rinsed off. The responders will then proceed to the next station, at which they will be thoroughly scrubbed with the appropriate decon solution and then rinsed.
Walkers or large traffic cones may be provided to ease the transition of the responders off of each of the previously mentioned stations. The responders will then proceed to a station at which they will be assisted with removing their PPE, which will be placed in appropriate containers.
The last element of PPE that is removed is the SCBA — or other respiratory protection — facepiece. The responders will then rinse their hands in a handwash bucket and will transition to medical monitoring. In some instances, the removal of the clothing of responders may be necessary if a suit malfunction has occurred.
It is imperative for Decon Group personnel to communicate effectively with personnel proceeding through decon to ascertain their air supply level and/or any equipment malfunctions; and also to ensure that easily understood commands are given to the responders — e.g. “turn around,” “raise your arms,” etc. Personnel proceeding through decon should also advise Decon Group personnel as to the areas of greatest potential contamination.
The extent of technical responder decon should coincide with the nature of the contaminant. For example, a thick, sticky, persistent liquid should call for very thorough decon procedures, while in dealing with a vapor contaminant the bulk of the contamination will sometimes diffuse in the relative airflow while walking from the hot zone to the Decon Area. In addition, the areas usually presenting the greatest threat for harboring contaminants include the soles of boots, gloves, any fold or crease in the PPE, and in Level B PPE the area between the SCBA and the splash-protective suit.
The equipment utilized in decon operations should also be selected to minimize the potential for contamination for Decon Group personnel. Long-handled brushes should be used, and the long-handled spray wands sold to water plants serve as an inexpensive and useful rinse tool. When all responders have exited technical responder decon, the Decon Group personnel then proceed to “collapse in” from the hot zone end to the cold zone end, deconning themselves in the process.
The two categories of mass decontamination — emergency and technical mass decon — are employed when large numbers of civilians have been contaminated. In emergency mass decon, a water supply is secured and fire apparatus are placed with their pump panels to the outside of the Decon Area, forming a corridor. Fog nozzles are placed on the 2 ½” discharge ports (angled towards the hot zone) and deck guns with fog nozzles may also be utilized. The nozzles are set on a medium to wide fog pattern and pumped at low pressures to provide for a gross rinse of contaminants.
An aerial ladder or tower can also be set up to serve as an overhead shower, and a handline flowing a low-pressure fog stream may also be used. A key item to remember is that if the clothing of a contaminated civilian is removed, up to eighty percent of the contamination is removed also. We as responders attempt to provide measures for modesty in such situations, however such measures may take a back seat when massive numbers of civilians are involved.
Technical mass decon is — as the name implies — a more thorough version of emergency mass decon. Commercially available tents with integrated showers are often used for ambulatory civilians, while roller systems are utilized for the decontamination of non-ambulatory citizens. The advent of decon trailers for both technical responder and technical mass decon has been a fairly recent and welcome innovation that makes life easier for Decon Group personnel, offering a very easy and timely setup.
Another thought that bears remembering in terms of technical mass decon is that we should remember the outside resources available to us. Some hospitals can provide deployable decon capabilities, and the State Medical Assistance Teams can also be relied upon for decon operations.
In summation, although the Decon Group is not often viewed as the most “desirable” assignment on the hazmat scene and decon operations in general are not usually the portions of a hazmat response shown in the movies, the process of decontamination is an essential part of hazardous materials response that demands a thorough knowledge of the procedures and has a direct impact on the safety and well-being of responders and citizens. As always, stay 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.