Decon is the hazardous materials equivalent of catching the hydrant on a structure fire. Everyone wants to be on the nozzle, but if no one is securing the water supply not much is going to get done on a structure fire. On a hazardous materials response, the entry teams cannot be deployed into the Hot Zone until the decon corridor has been established and staffed. The supervision of the decon corridor and all thing pertaining to decon are the responsibility of the Decon Officer.
The Decon Officer must know the four main categories of decon. They are emergency decon, gross decon, technical decon and mass decon. Emergency decon is used in potentially life-threatening situations, regardless of whether a formal decontamination corridor has been established. Emergency decon is used when an operator in the Hot Zone suffers a medical emergency while wearing chemical PPE and must be removed as soon as possible so that medical intervention can take place. Simply stated, if one of our members suffers cardiac arrest while wearing Level A, we don’t have the time to run that person through the formal decon corridor. It may take five to 10 minutes to completely decon someone and get them out of the suit.
If brain tissue starts to die after four to six minutes without oxygen, you can see why emergency decon is the method of choice here. If the victim is one of our own, we douse them with water to get as much contamination off of them as possible. We then remove the PPE from them and get them the treatment that they need. If the victim is a civilian, we remove contaminated clothing and douse the victim with water. In either event, formal decon may be instituted once the medical emergency has been treated, Gross decon and technical decon are both used in the decon corridor that is established within the Warm Zone. In some literature you may see the entire decon corridor referred to as “technical decon.” Gross decon is usually done in the first pool in the decon corridor. This station is simply a rough wash to remove most of the contamination from the operator or victim. Technical decon is performed in the second pool in the decon corridor where much closer attention is paid to removing contamination. Technical decon pays special attention to the major joints of the body where contamination may hide in the folds of the suit. These joints include the elbows, armpits, knees and crotch. Technical decon also applies to areas of the body that see the most contamination such as the hands and the bottoms of the feet. Any areas of the suit that contain large folds where contamination may hide are also addressed here.
Mass decon is the type of decon that no one wants to think about, but we must be ready to implement. Technical decon is used for our entry teams and a few contaminated victims. Mass decon is used during mass casualty incidents where we may have to decon dozens, hundreds or even thousands of victims that have been exposed to a chemical. This would more than likely be a terrorism scenario where are large group of people was targeted in a shopping mall, sporting event, etc. During mass decon, we utilize a corridor built with our apparatus and run the victims through the corridor under a continuous shower of water. There is no right or wrong answer as to how to build your corridor. It all depends on your apparatus fleet. The possibilities are endless with some combinations including two engines, four engines, two engines and two ladders, four ladders, etc.
Now that we have discussed the four categories of decon, the biggest question is a rather simple one. Do we use a “wet” decon or a “dry” decon? Wet decon is the most common and our standby. Water is cheap, effective, readily available and relatively stable. The only thing that water cannot and must not be used on is Class 4.3 Flammable Solids and other materials that are water reactive. On incidents where we are dealing with water reactive chemicals or radioactive materials, a dry decon must be used. Dry decon is used on radioactive materials because water spray may spread the radioactive particles outside of the decon corridor. Water will also not dilute a radioactive material like it will dilute other hazardous materials.
The layout of the decon corridor will vary from team to team based on the needs of the incident and the chemical or chemicals involved. The Decon Officer will decide how many people will staff the corridor and how the corridor will be built. Most corridors will include a tool drop, a gross decon pool, one or two technical decon pools and an undressing station where the team member will have their PPE removed or where the victim will have their clothing removed before they are transferred to EMS for triage, treatment and transport.
We have talked about the categories of decon, wet and dry decon and the decon corridor. The last thing a Decon Officer needs to know is what method of decon to use. This could be much more involved than a simple shower and removal of PPE as there are 10 different methods of decon.
Absorption is where a spongy material is mixed with a liquid hazardous material. The contaminated mixture is then collected for disposal with the rest of the hazardous waste generated during the response. It is used to decontaminate equipment and property. It is most effective only on flat surfaces but is less effective on areas that have void spaces or other nooks and crannies where contamination may hide. If you’ve ever cleaned up a spill at your house with a paper towel, you’ve already practiced absorption.
Adsorption sounds a lot like absorption, but it is completely different. Adsorption is where the contaminant adheres to the surface of an added material such as sand or activated carbon or charcoal. Adsorption is used when a hazardous material is ingested and activated charcoal is administered in order to soak up the material and prevent it from doing further damage to the stomach.
Dilution uses plain water or a soap-and-water mixture. It is fast and economical and used in gross, technical, mass and emergency decon. When using dilution, there are certain factors that must be taken into consideration. Will the contaminant react with water? Is the contaminant soluble in water? Will the contaminant spread to a larger area? How much will the water used increase the hazardous waste generated? All these questions must be answered by the Decon Officer.
Disinfection is a term that we don’t usually associate with hazardous materials response, but it is another method of decon. Commercial disinfectants are available that destroy disease-carrying microorganisms. They are packaged with a detailed brochure that describes the limitations and capabilities of the product. Disinfection is used at facilities that may have biological hazards such as research labs, hospitals, clinics, mortuaries, medical waste disposal facilities, blood banks and universities.
Disposal is a two-step process for items that cannot be properly decontaminated or are considered disposable. The contaminated item is removed and isolated, then packaged and transported to an approved facility. Contaminated disposable coveralls and other PPE items should be collected, bagged, and tagged for proper disposal. Contaminated tools and other equipment should be placed in bags, barrels, or buckets and tagged for proper disposal. Please keep in mind that these materials are considered hazardous waste and must be disposed of as such. They must not be thrown away with the normal trash.
Solidification is a chemical process to turn a hazardous liquid into a solid. It makes the material easier to handle and does not change its inherent chemical properties.
Emulsification is a process that changes the chemical properties of a hazardous material. It neutralizes the material and reduces its harmful effects. Federal, state, and local regulations may apply to the use of emulsification products. There are some limitations to using emulsification. The contaminant still requires proper disposal. The chemicals used in emulsification may be harmful to civilians, emergency responders or clean-up contractors. Time is required to determine which chemicals can be used and to determine their availability.
Vapor dispersion is the process of separating and diminishing harmful vapors. Water spray is commonly used but mechanical or natural ventilation can also be used as methods to disperse vapors. (The process of ventilating a structure during and after a fire is an excellent example here.) Use extreme caution here as a rapid introduction of a large volume of air can create dynamic and harmful results.
Removal is used specifically for dealing with contaminated soil where the toxic materials cannot be rendered harmless and on-site treatment poses high risk. In most cases, it will be more economical to remove and dispose of the contaminated soil as opposed to treating it on site. Removal reduces clean-up time and limits exposure risk to civilians, emergency responders and clean-up contractors.
Vacuuming is the process used during a dry decon. It is very effective in the removal of dusts, particles, and some liquids by sucking them into a container. Filtering systems on the vacuum devices prevents recirculation of contaminated material. (This is a concern when dealing with radioactive materials.) HEPA vacuum cleaners are used to remove contaminants that are 0.3 microns or larger.
Decon is a HazMat Operations level skill. The Decon Officer will usually be either an officer on the HazMat Team or one of the senior technicians or specialists. The Decon Officer will guide you through setting up the corridor, making sure you have the right personal protective equipment and make sure that you accomplish your mission safely in order that you and those that you decon go home safely.
Until next time, make sure that everyone goes home well.