More specifically, deaths (with one known exception) have resulted from the abuse of Bromochlorodifluoromethane (BCF or Hal on 1211). These are usually recognisable as green extinguishers. Hal on is a vaporising liquid fire-extinguishing agent with a boiling point of 4⁰C. It is particularly effective against burning liquids and electrical fires. It acts in part by forming a blanket of gas, which will not support combustion, and interfacing with the chemical chain reaction taking place in the flames.

Incidence

Fire extinguisher abuse has been a feature of VSA for many years. However, it is only recently that a marked increase in the deaths and incidence has been noticed. A study of deaths resulting from the abuse of volatile substances, 1971 to 1992, identified 54 deaths from the abuse of fire extinguishers in this period. 1990 saw a dramatic increase of incidents reported in the British press, and in that year alone there were 16 deaths. This is a problem that mainly involves young people between 14 and 18, usually male. Inquests often report that it was a group activity and frequently there are indications that death occurred at a first or near first attempt. This indicates the strong involvement of "peer pressure" in these incidents.

A Peckham bus company reported more than 360 fire extinguishers stolen from their premises in five months. Thefts from bus stations and railway depots appear to be the principal source of supply of extinguishers. Schools are another potential source. Missing extinguishers may obviously significantly affect fire safety. The Fire Extinguishers Trades Association states that they are "actively reviewing the ways in which we can assist customers and users so as to reduce the theft of extinguishers which has been associated with the increase of Halon solvent abuse and sniffing".

Effects of abuse

When "sniffed", halon produces a strong narcotic and anaesthetic effect, and can cause hallucinations. Experimental animal studies indicate that high concentrations of halon 1211 (20 to 25 gimI) in the bloodstream, can cause serious cardiac arrhythmia. Sudden death is thought to be caused because BCFs

sensitise the heart to the arrhythmogenic action of adrenaline.

The higher the concentration, the shorter the time required to achieve hazardous bloodstream concentrations. Most deaths appear to occur quickly, unconsciousness occurring within minutes of inhalation.

Halon fire extinguishers

Halon gas extinguishers are designed for fighting electrical fires. They are used in large computer installations, where equipment can be worth millions of pounds. Halon extinguishers are also commonly installed in schools with computer equipment and on public transport. The extinguisher is recommended by fire safety officers as a good agent for putting out fires. Carbon dioxide fire extinguishers are effective, but they are relatively much heavier, as well as more expensive.

Halon is due to be phased out under the Montreal protocol to protect the ozone layer. It has, over recent years, enjoyed some popularity as a substance of abuse, with the majority of the 54 (4%) deaths from fire extinguishers (1971-1992) attributable to it. Little is known about its possible chronic toxicity when abused.

A vital function of a fire extinguisher is safe, effective and reliable operation. The inclusion of 'stenching' agents has been considered, but the reliability of the extinguisher is affected by the purity of the BCF. Such agents obviously must not interfere with the performance or storage of the appliance. Tests have been conducted with mercaptans (sulphur-based stenching agents) and ammonia. Mercaptans are ineffective at high concentrations and ammonia is itself acutely toxic and could seriously compromise the appliance's use by a legitimate user.

The UK Government signed the Montreal Protocol at the United Nations, and it was decreed at a revisionary meeting that the production of BCF for fire extinguishment should be reduced by 50% for environmental reasons by 1995, and completely phased out by the year 2000. Existing BCF fire extinguishers are gradually being replaced by carbon dioxide versions.

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