Decontamination Considerations in Dealing With A Chemical Agent Mass-Casualty Incident

Decontamination is a common activity at hazardous materials (hazmat) incidents of all types. Ideally, members of well trained hazmat response teams routinely set up, manage, and coordinate decontamination operations – and in most situations it is only the members of the hazmat response team themselves who need decontamination.  But the release of a chemical agent in a populated area can quickly create a mass-casualty incident that requires a much larger-scale operation – involving, in most if not all cases, the decontamination of not only the hazmat team members and other emergency responders but also hundreds or possibly thousands of other people. Such operations almost always need more resources than those dispatched after the first alarm.  

A major challenge facing emergency responders is to quickly find out which and how many casualties need immediate decontamination. Ideally, all casualties should be prioritized for decontamination in accordance with certain well-defined guidelines (discussed below).  However, when there are large numbers of victims who may have been contaminated, the challenge becomes much more difficult – so much so that it is frequently impossible for firefighters to prioritize them in a timely way. Nonetheless, decontamination is still needed for those who have been exposed to a chemical-agent aerosol or liquid and/or who show symptoms of exposure. That is the most pressing current decontamination issue, regardless of other factors, including the number of firefighters available at the scene of the incident.

Time is crucial to the success of decontamination operations. The shorter the time is between casualties’ exposure to a chemical agent aerosol or liquid and the time when they have been decontaminated, the more successful the decontamination should be.  Depending on the chemical agent involved – for example, the nerve agent Sarin, which can be lethal after only a short exposure – the decontamination efforts by firefighters may serve primarily, or only, to remove residual liquid and to prevent secondary contamination.

A cautionary note: Although most people who are in the exposure area may not have had direct or even indirect physical contact with the chemical agent, they still should be considered for decontamination, if only as a precautionary measure.  

Training, Exercises, and Protective Equipment

Preparatory training, combined with tabletop drills and full-scale exercises, for a mass-casualty decontamination operation will help firefighters develop a better understanding of and appreciation for When there are large numbers of victims who may have been contaminated it is frequently impossible for firefighters to prioritize them in a timely way the physical resources and logistics planning needed, along with the close coordination also required, to decontaminate large numbers of victims. The success of these exercises depends on, among other factors, the realism of the scenarios, the number and interest of participants, and the setting of reasonable goals for the exercise. As a rule of thumb it is safe to assume that the more artificiality that is added to the exercises the less unrealistic the outcome will be.

As firefighters know, their customary turnout gear does not give them the same or as much personal protection as that provided by protective ensembles specifically designed for use in chemical-agent environments. When the latter (i.e., the protective ensembles) are not available, the incident commander must decide – taking into consideration the conditions at the scene of the incident and, if possible, input from the hazmat team commander – whether firefighters should participate in the rescue operations needed to remove casualties from the contaminated area. Except in rare situations, it usually would be impractical for hazmat team members wearing encapsulating protective ensembles to engage in the rescue and decontamination of scores or hundreds of casualties.

Dealing With Decontamination Water

Although water runoff from decontamination operations (deconwater) can have harmful environmental consequences, firefighters should not delay the decontamination of casualties simply to control runoff.  In 2000, the U.S. Environmental Protection Agency dealt with this matter by issuing a Chemical Safety Alert titled First Responders’ Environmental Liability Due to Mass Decontamination Runoff.  Following is an excerpt from that report: “During a hazardous materials incident (including a chemical/biological agent terrorist event), first responders should undertake any necessary emergency actions to save lives and protect the public and themselves. Once any imminent threats to human health and lives are addressed, first responders should immediately take all reasonable efforts to contain the contamination and avoid or mitigate environmental consequences.”

Decontamination Prioritization

According to another report – Guidelines for Mass Casualty Decontamination During a Terrorist Chemical Agent Incident, prepared by the U.S. Army Soldier and Biological Chemical Command – decontamination operations should be carried out in accordance with a pre-established level of priorities, as follows:

1. The highest priority for ambulatory decontamination is reserved for those casualties who were closest to the point of release and report that they were exposed to an aerosol or mist, who have some evidence of liquid deposition on their clothing or skin, and/or who have serious medical symptoms (for example, shortness of breath, chest tightness, etc).
2. The next priority is ambulatory casualties who were not as close to the point of release, and who may not have evidence of liquid deposition on clothing or skin, but are clinically symptomatic.
3. Casualties suffering from conventional injuries, especially open wounds, should be the third priority.
4. The lowest decontamination priority is reserved for ambulatory casualties who were some distance away from the point of release and who are asymptomatic.

Here, another cautionary note: Although a prioritization of the decontamination process is always desired, it may not always be finished quickly enough to justify the benefits achieved. The critical factor here is the number of casualties at the scene of the incident compared with the number of first responders immediately available to triage and prioritize them. The greater the number of casualties identified for decontamination, the greater will be the workload for the firefighters assigned to carry out the decontamination. In addition, of course, the longer the time between chemical agent exposure and decontamination, the less beneficial decontamination is likely to be.  However, to totally ignore decontamination is not a viable option.  

Another rule to remember is that firefighters should not transport casualties who need medical attention to a hospital or other medical facility without first decontaminating them. This rule is required not only for the safety of the casualties themselves but also for the safety of emergency medical technicians and hospital personnel as well.

The various recommendations mentioned above (and in the references below) are intended not only to stimulate interest but also, and of greater importance, to evoke action by firefighters, and incident commanders, to develop and disseminate written guidelines for the decontamination of casualties as soon as possible after a chemical agent mass-casualty incident has occurred.  The decontamination of a relative handful of casualties is not considered by most fire departments to be a particularly difficult task – but the decontamination of hundreds of casualties could and would be a major challenge to even the largest and best equipped municipal and county fire departments.

Prioritizing casualties for decontamination, protecting firefighters, selecting the most efficient methods of decontamination, and addressing the problems caused by deconwater runoff are only some of the key issues that need attention when planning for and managing a terrorist chemical agent mass-casualty incident.  Without a comprehensive mass-casualty incident management plan in place ahead of time, the nation’s firefighters are likely to dissipate much of their time in on-scene remedial operations that fall far short of the real goal – namely, the timely and efficient decontamination of a large number of casualties. 

Fire chiefs are encouraged to read the following report:
Risk Assessment of Using Firefighter Protective Ensemble (FFPE) with Self-Contained Breathing Apparatus (SCBA) for Rescue Operations During a Terrorist Chemical Agent Incident.

The following reports are recommended for additional information:
Guidelines for Mass Casualty Decontamination During a Terrorist Chemical Agent Incident (January 2000)
Guidelines for Cold Weather Mass Decontamination During a Terrorist Chemical Agent Incident (January 2002, revision 1, August 2003)