Every fire officers knows about the effects of an overt terrorist attack - such as happened on 9/11 in New York or the release of Sarin in Tokyo’s Metro system in 1995 or at the multiple bombings in London on July 7th.
However, an attack in a built-up area with high population density involving a car or truck bomb or rail tanker, using readily available industrial chemicals such as chlorine or phosgene would be much more devastating and easier to organise, procure and execute.
The worst possible scenario would involve a thick viscous, tacky material of the consistency of polymerised used cooking oil, contaminated with highly toxic chemicals and radioactive material, dispersed efficiently over a large area by detonation as an aerosol on a windy day. The difficulties in decontaminating any exposed surfaces, including equipment and people, would soon turn the incident into an operational nightmare.
Chemical, biological, radiological, or nuclear have both similarities and differences. Similarities include:
* A need for modified triage procedures which distinguish between people who are externally or internally contaminated. Some of these procedures may go against cultural and professional ethical patterns of behaviour since the most seriously injured may have to be ignored so that paramedic and medical resources can do the greatest good to the greatest number in situations where there are a very large number of casualties, i.e., greater than a few hundred;
* Treatment of contaminated personnel, whether members of the public or first responders, will usually consist of using absorbents, washing-off and, where possible, destruction of the toxic agent, e.g., with hypochlorite, peroxyacetic acid or alkaline solutions - washing-off does, however, generate problems of disposal for the run-off water;
* Scaleability is a very real problem - what you can do effectively for 20 people is almost certainly not applicable to 200 or 2000.
Be aware of the issues: With CBNR or complex HazMat incidents, more than any other type of operational activity, it is essential for senior officers and incident commanders to understand clearly the differences between the various agents involved.
* Chemical substances are often relatively easy to detect quickly and specifically, and chemical inactivation such as neutralisation or hydrolysis may be possible;
* Biological agents again are relatively easy to inactivate but specific detection may take time and spore formation, e.g., with anthrax or clostridia, may present long term problems, as may transmission within the population at large after a lag phase;
* Radioactive isotopes can be detected immediately and identified extremely specifically, although inactivation is not possible and some isotopes are extremely long-lived and are concentrated by specific organs of the body.
Agents used as weapons Whether or not a particular agent counts strictly as a chemical or biological weapon, e.g., sarin, mustard gas, the anthrax bacillus or the smallpox virus, depends on whether it is listed by the United Nations under the relevant conventions. Many highly toxic industrial chemicals or biological agents can also be used as weapons.
Some are listed in international agreements or national legislation such as the UK Chemical Weapons Act 1996, others are not. Of particular interest here are the Schedule 3 materials in the Chemical Weapons Convention (CWC), so-called ‘dual use’ materials such as phosgene, hydrogen cyanide or phosphorus oxychloride.
Materials like these have a perfectly legitimate civilian use in the chemical process industry but may also be used as precursors for chemical weapons or as weapons in their own right.
Unfortunately many of the materials required for pesticide manufacture are the same as those required for the production of organophosphorus nerve gases.
Many radioisotopes are chemically toxic in their own right, and there are some 800-900 listed in the UK Ionising Radiations Regulations 1999. They may also be radiotoxic, causing severe tissue damage if ingested or absorbed.
Lethal exposure and severe skin radiation burns are caused by high activity beta emitters, as happened with Russian firefighters at Chernobyl. Radioisotopes cannot generally be destroyed like many other chemicals and some are very longlived, having half-lives of the same order of magnitude as the age of the Earth.
In many respects the distinction between radiological (R) and nuclear (N) categories is artificial. Both involve materials producing ionising radiation with its attendant dangers of internal and external exposure, contamination of the environment and difficulties in decontaminating people and equipment. The nuclear power industry handles very high levels of radioactivity whereas nuclear weapons possess the additionalrisks of blast, thermal radiation and wide dispersal. Some countries, such as Germany, use highly specialised small, mobile, state-of-the-art laboratory vehicles as part of the initial fire service response but detection facilities vary widely from brigade to brigade and country to country. Vehicles may be equipped with a variety of sampling equipment such as Draeger(tm) detection tubes, a gas chromatograph-mass spectrometer, or an infrared spectrometer, for the rapid and quantitative detection of hazardous materials. Other fire services, especially in the UK, may rely on external commercial scientific advisers who have to be mobilised and travel to the incident.
Biological agents are a relatively new hazard for fire service incident commanders. These materials may be classified broadly as infectious agents, for example, anthrax bacilli or smallpox viruses, or as biological toxins such as ricin or botulinum toxin.
Biological agents, although often active in submicrogram amounts, are relatively easy to protect against in terms of PPE but easily dispersed so that spread is a problem. Destruction of biological agents is frequently easier than for other hazardous materials unless the agent, such as the anthrax bacillus, is able to produce hardy, longlived spores which may survive in the environment for decades - for example, the contaminated island off the Scottish coast.
Disinfection with suitable chemicals, including hypochlorite (bleach) or peroxyacetic acid may be effective. Some of the most effective nerve agents are destroyed relatively quickly by alkaline solutions.
Decontamination is a serious operational problem. Although current procedures may be limited to dealing with a couple of dozen contaminated first responders or members of the public, with very large numbers such as might be encountered in an inner-city terrorist CBRN attack, i.e., 1,000 - 10,000 people, the way in which decontamination is carried out or even whether it is carried out, will have to be rethought.
The fire service may take a ‘strip, bag and burn’ approach as a means of saving resources and the only way of dealing with a huge number of civilian casualties. It may be impossible to decontaminate PPE effectively enough so that it can be reused safely and doing so may put other personnel at risk. A risk reduction strategy of immediate disposal may be considered cost-effective and one that also avoids the risk of further contaminating the environment with run-off water.

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