You are here

Gas! Gas! Gas!

Article, 13 November 2007
Domestic Security, Technology, Terrorism
This article examines how training for one high-consequence scenario, an incident involving a weapon of mass effect, can be enhanced through the use of a Chemical Agent Monitor (CAM) simulator.

How Realistic is Realistic?

There have always been problems associated with making the training for high-risk scenarios too realistic. Within the military, for example, small arms training involving live ammunition is carefully managed and only introduced when recruits have attained a minimum skill level in the 'dry' environment. Similarly, within the bomb disposal fraternity, on the job training is not generally considered a reasonable option. For those who regularly travel across the North Sea in helicopters, practical Helicopter Underwater Escape Training (HUWET) became a statutory requirement when, in tragic circumstances, the limitations of relying on plasticards and videos became all too apparent. In each of these examples, the consequences of the trainee getting it wrong (through ignorance, poorly learned drills or being unfamiliar with equipment, for example) are likely to outweigh savings in time or money obtained through sub-standard training.

In terms of preparing for a chemical attack scenario, the problems of training in a highly realistic environment are compounded because of the magnitude of the risks if a live chemical material was to be used. That is not to say realistic practical training is not possible at all. The wearing of personal protective equipment (PPE) can be simulated almost anywhere - a knockabout on a football pitch involving opposing teams clad in full PPE is but one example of how to simulate a sweat bath. The CS confidence chamber is also invaluable for proving two things: (a) that the service respirator works against CS, if worn correctly; and (b) the student has indeed learned to wear the respirator and perform the associated drills correctly. The highly visible consequences of the student getting it wrong in the CS chamber are rarely more serious than vomiting and humiliation - usually in that order. However, any difficulties presented in terms of PPE rapidly pale to near insignificance when the issue of training realistically with chemical monitoring or detection equipment is considered.

Chemical Agent Monitor (CAM) Training and Exercise'itis

The military (the driver in terms of chemical detection and protective equipment training) traditionally use two techniques to simulate the initial detection of, and down-wind hazard associated with, a chemical material. The first involves deploying a range of relatively benign simulants, from the aforementioned CS for human systems, to DPM; a chemical sometimes used to replicate a nerve agent alarm in electronic monitoring equipment. The second, and less sophisticated approach, involves an NBC instructor shouting 'Gas! Gas! Gas!' and abusing anyone who, in his opinion, fails to react appropriately. The said instructor then approaches a hapless student and tells them what (again, in his opinion) the equipment has just 'done', demanding, in return, a rundown of the immediate actions. ("Come along now. I know the display is blank and the wind is blowing away from you, but use your imagination. Eight bars of 'G'. What are you going to do? Eh? Eh? Eh?"). A spectacle that is frequently entertaining but rarely instructive in terms of measurable results.

The chief drawback with both of these approaches, even if conducted with greater diligence than that alluded to above, is: do they teach the right lessons? Chemical simulants (DPM or MS), for example, are notorious for being waffted away at just the wrong moment or, if actually detected, for producing readings that are too high/not high enough. While this is clearly realistic in terms of the behaviour of volatile chemical compounds, it is also frustrating when the exercise scenario requires a positive detection, at a certain equipment reading, at a certain point in time and space. There is also a potential problem when the same training venue is used regularly. The unexpected detection of residual vapour from a simulant laid down during previous scenarios does little to enhance the credibility of the trainer or the exercise.

For those who take the issue of training seriously, the solution to these problems is often: (a) to use instructors that know the subject inside out (and are therefore well placed to manage the 'unexpected' in a realistic way); and (b) to have an instructor/student ratio approaching 1:1. Neither option is necessarily easily achievable and both are associated primarily with measuring a student's performance against subjective criteria. In addition to the issue of subjectivity, such close supervision can have a distracting effect on the trainee. For instance, when being observed so closely, it cannot be certain whether the student is playing the exercise game (i.e., trying to please the instructor), or doing what they would do operationally if left to their own devices. This dilemma is an area of research that has long interested psychologists, particularly in relation to how instructions are followed when a subject knows their behaviour is under close scrutiny. (For example, during the 'Blitz' of the Second World War, windows that could not be seen easily - except by the Lufftwaffe of course - were sometimes less well blacked-out than those readily visible to ARP Wardens.) Within the military, the phenomenon of developing expedient shortcuts when not being supervised is sometimes referred to as D.S. watching (i.e., concentrating only on those things the Directing Staff [D.S.] can see - and only when the D.S. are watching!) At best, this is just lazy; at worst, risks to which the student (and their colleagues) may be exposed in an unsupervised operational setting are magnified greatly.

Simulating the Detection of a Chemical Material

Whether simulating conditions on the battlefield or in urban terrorism scenarios, the problem is how to ensure training:

  • is realistic;
  • provides measurable results (ideally, with a high degree of objectivity);
  • does not intimidate or otherwise affect adversely the student; and
  • does not teach the wrong lessons.

Within the British Transport Police these issues were first identified in relation to chemical monitoring equipment following the Aum Shinrikyo (ASK) sarin attack against the Teito Rapid Transit Authority (TRTA) in Japan, in March 1995. In that incident, the police response was hindered both by the inability of the emergency services to determine rapidly what caused the casualties and, once a chemical attack was suspected (approximately sixty minutes after the release), how far it had spread. Part of the solution adopted to protect the rail network in general and the London Underground in particular, was the introduction into police service of a Chemical Agent Monitor - CAM - produced by Smiths Detection.

From the outset, it was clear that the limitations sometimes associated with military training (the application of overactive / underactive imaginations and/or chemical simulants) applied equally to the police environment. The partial solution was identified in the form of a CAM simulator that utilized the properties of ultrasound and magnetic fields - rather than chemical simulants - to replicate the characteristics of volatile gases (the Argon Electronics CAMSIM). The properties that make this type of simulator particularly useful in the police environment can be summarized as:

  • Automatic Recording of Errors. Because errors are logged automatically - from failure to set-up correctly, through monitoring procedures, to failure to shut down correctly - the instructor can stand back, yet measure a student's performance against objective criteria.
  • Reliability. Once a scenario has been set-up using the ultrasound or magnetic sources, each student will encounter a near identical scenario. When in range, the CAMSIM alarms; however, if the 'vapour' sources are turned-off, or are out of range, there is no residual vapour to confuse the scenario.
  • Credibility. The appearance and performance of the simulator realistically mirrors that of CAM itself. For example, if a student uses CAMSIM too quickly, the contamination source may well be missed; if used too slowly or allowed to touch the source, the simulator will respond as if it has become contaminated.
  • Ease of use. Using the instructor-only controls, CAMSIM can be interrogated for errors, reset and re-deployed rapidly. The remote control feature is particularly useful in simulating the success (or otherwise) of decontamination procedures.
  • Health and safety. The use of non-chemical sources avoids the inevitable debate about the possible hazards posed by chemical simulants - both in relation to use and storage.
  • In terms of limitations, there is no doubt that cost is an issue for many potential users. However, the CAMSIM is unique and adds a dimension to training that could not be otherwise simulated. Indeed, in many respects, and notwithstanding the observations made in this article already, it is difficult to see how organizations with CAM, but without CAMSIM, are able to train in depth at all. Another criticism sometimes levelled is that the confidence test device (a means introducing a small amount of simulant into the CAM to produce a reference peak) is of a pattern supplied in the US and is not identical to the UK design. This is a valid point, but one that does not detract in any significant way from the overall performance of the simulator itself.


    The technology used in CAMSIM will always attract criticism from those who believe a gas detector simulator should detect any sort of gas, rather than a form of stimulus over which a trainer or exercise setter has an element of control. Through the use of ultrasound and magnetic fields, CAMSIM does provide both realism and measurable results in a form that would not otherwise be possible. From the perspective of the British Transport Police, its use has improved both the confidence and capability of CAM operators and, despite the high initial outlay, the equipment has proved cost-effective. At a time when the operational readiness of safety-critical monitoring equipment is of concern to many people, the process of active training must seek to prove more than that a 'gas detector' can 'detect' gas.

    Adrian Dwyer is Counter-Terrorism Advisor, British Transport Police

    Support Rusi Research

    Subscribe to our Newsletter