identify the exact identity of the agent. Knowing the class of agent allows you to begin an effective evacuation process, detain potential casualties, begin mass de-contamination, and initiate medical treatment. Identifying the exact identity of an agent can take a long time. This is especially true when responders are only equipped with field detection equipment and must send samples to a lab for final identification. I am, of course, aware that this approach is not foolproof, and that there are certain agents that must be absolutely identified before medical treatment can begin. These agents however, are typically very hard to get hold of, or relatively ineffective as CBRN agents. This idea, like many CBRN response protocols, does not ideally cater for biological threats. This is due to the undetectable incubation period of biological agents and the need for extensive laboratory testing.
Certainty
A fundamental question asked during this study was ‘do responders ever need to be 100% certain of agent identity?’ The answer to this, perhaps predictably, was no. At no point in any of the scenarios posed to the volunteers did they require 100% certainty of agent identity. This study suggests that not only do protected first responders not require 100% certainty of agent identity before making urgent decisions, but that the vast majority will make these decisions at around 50% certainty. The psychological and emotional justifications for this were not in the scope of this study, but would no doubt make interesting reading.
One scenario posed to the volunteers in this study asked how they would respond to a CBRN scene with 50% certainty of a nerve agent being present. The results suggested the majority of responders (89%) would evacuate and cordon the area, in other words they would, at least, begin the decision- making process. It is worth noting that few responders would re-test the area using detection equipment. In contrast to this, when an indentical scenario was presented to volunteers, but instead of 50% certainty
of a chemical agent there was 20% certainty, less than half of the volunteers were prepared to make any major decisions and the overall consensus was to test again using DIM, to get a higher degree of certainty.
This tendency of responders to make urgent decisions at around 50% certainty of agent identity led to the idea of a ‘50% threshold of response’. This idea simply suggests that once protected responders reach 50% certainty of agent identity, a series of critical decisions can be made - some of which have been mentioned previously. It is also worth noting that if responders are 50% certain of the identity of the agent they will be far more than 50% certain of the class of agent. This reverts back to what I discussed earlier and may allow for a more rapid response.
Don’t ask what it is, ask what it does On first meeting a senior CBRN responder one of the first things he made clear was that, in his words, “The [detection] equipment is there to assist our decision making, not dictate it”. This is an important point, and one that I feel may have been forgotten. After all, detection equipment is only as good as the interpretation of its data. The number of detectors available on the market for each discipline of CBR is immense. Even so, all detectors have their limitations. False positives and even false negatives are issues responders must be constantly aware of. Most chemical detectors, for example, use a technology called ion-mobility spectrometry (IMS). IMS works by separating and identifying molecules based on their mobility through a drift tube. A determining factor in IMS detection is the length of the drift tube: the shorter the drift tube, the less time the molecules have to separate - so (in general) these detectors are more susceptible to false positives. This is particularly noticeable in confined spaces where concentrations of inert contaminants are high. Another type of detector used by responders is the gas chromatography/mass spectrometry (GCMS) unit. Interpretation of data from GCMS is not always easy – it would be a brave individual that would want this
responsibility at a CBRN incident scene with no scientific background. Without a good understanding of the detection processes it is far more difficult to appreciate the limitations of a detector and may have the effect of making someone too dependent on that detector and not on other signifiers [Mark One Eyeball is an under-rated detector Ed.].
I am, of course, not suggesting that responders do away with detection equipment. I am simply suggesting that there is a disproportionate emphasis and/or reliance on detectors. Instead of trying to establish exactly what the agent is, a more relevant question would be: what does this agent do? More specifically, how does this agent affect the human body? Symptoms can tell you as much about an agent as detection equipment, and the risk of false positives are arguably lower. It is clear from the questionnaire that many of the volunteers were aware of this. One volunteer even stated “No casualties, no response”. There are many cases where a positive ID from a detector will be dismissed as a false positive, but responders are less likely to dismiss symptoms presented by a casualty. In the 1953 ‘Detection and Identification of War Gases,’ published by the Home Office, it states under ‘Classification’ that “War gases differ considerably in physical properties and chemical nature, and the only reasonably satisfactory way of classifying them is according to the effects which they produce on the human body.” So the argument of ‘don’t ask what it is, ask what it does’ seems to have been very much accepted at that time. There is no doubt that detection technology has vastly improved since 1953, however I feel that this message is still relevant today and may have been somewhat forgotten in the race to find more accurate, faster detector technology.
A Suggested Model of Response The data obtained from the volunteers in this study allowed me to develop a suggested model of response to CBRN incidents. This model, shown below, is based on how volunteers reacted to varying levels of certainty and their
www.cbrneworld.com CBRNe South America 2012, 13-14 March, Rio De Janeiro, Brazil. More information on
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February 2012 CBRNe WORLD
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