Air Raid Precautions Handbook No. 3, 1st Edition

MEDICAL TREATMENT OF GAS CASUALTIES

HMSO. London 1937

CHAPTER I.

GENERAL DESCRIPTION OF WAR GASES.

1. Meaning of "Gas" in Chemical Warfare.

The term "gas," in connection with warfare, is used in a very general sense, to include any chemical substance, whether solid, liquid or true gas, employed for its poisonous or i-tant effects on the human body.

Such substances are, generally speaking, dispersed in the air as vapours or as poisonous smokes, and exert their action on persons breathing the air thus contaminated. Some of them, however, such as the blister gases, whether in the form of liquid or vapour, have also the power of acting directly on the skin.

Gases are generally classified in two main categories.

(a) Non-persistent substances which, when liberated, are rapidly converted into gas or smoke.

Clouds of gas so produced continue to be effective only until dissipated by dilution with the surrounding air.

(b) Persistent substances, which are generally liquids.

These liquids contaminate the objects with which theycome in contact, and continue to give off vapour for a considerable period; mustard gas, lewisite and most tear gases are typical examples. Both the liquid qnd the vapour are poisonous.

2. Notes on the Use of Gas in the last War.

Chemical warfare in the modern sense was first introduced by the Germans in April, 1915, on the Western Front, chlorine gas being used by them in successive attacks until May of the same year, when tear gases also were used. These attacks found the Allies not only unprepared, but also inexperienced in the effects that chlorine produces on its victims. The casualties sustained during this period of ignorance and unpreparedness cannot be estimated accurately, but they were very heavy, and improvised means of protection had to be adopted at once.

The first official respirator (a cotton pad soaked in thiosulphate of soda, glycerine and sodium carbonate) was issued in May, 1915, and after that date defence, on the whole, kept ahead of attack-so much so that phosgene gas, first used by the Germans in December, 1915, found the Allies relatively well protected against its effects.

With a view to overcoming this protection the Germans introduced the arsenicals (or "nasal irritants") and mustard gas. The former were intended to penetrate the box respirator which was then in use by the Allies, while the latter, having a very faint smell and causing no immediate irritation, might be expected to take effect before the need for putting on a respirator was realised. Comparative failure attended the use of the arsenicals; mustard gas, on the other hand, was only too successful, for, in addition to its insidious latency, the gas possessed the power to attack all parts of the body not protected by the respirator and had, in addition, the great offensive value of persistency.

The success secured by the use of mustard gas in the last war was chiefly due to the action of the vapour alone-vapour emitted from persistent deposits of the liquid. Mustard gas was then only used in shells; but there is no practical difficulty in using it in bombs or in the form of spray discharged by aircraft, when contamination of the hare skin and of clothing by the liquid might cause casualties over wide areas, if no precautions were taken.

In view of the properties of blister gases, however, which are capable of attacking other parts of the body which the respirator cannot protect, advice is being given to the public, to remain indoors in a gas-protected room during an air raid. Essential air raid personnel who might have to be exposed to risk of contamination in performing public services will be supplied by the Government with the necessary protective clothing.

3. Factors governing the Use of Gas.

It is evident that the higher the concentration of the gar. the shorter will be the period of exposure required to produce pathological damage; and the converse also holds good.

The effective use of gas may be markedly influenced by meteorological conditions as well as by topographical features in the area aflected.

A strong wind will rapidly dilute and disperse all concentrations of non-persistent gases, while in the case of a persistent gas the rate of evaporation of the liquid will he increased, thus tending to clear the area more rapidly. With a low wind velocity, on the other hand, a high local concentration may be obtained with both types of gases, and the persistency of such liquids as mustard gas will be markedly lengthened, in the absence of other adverse factors.

Temperature plays an important role, both by influencing the diffusion of the gas by convection currents and by affecting the persistence of such liquids as mustard gas; hence warm sunny weather is inimical to the most effective use of gas. On the other hand, very cold weather has its disadvantages too, as it very markedly reduces the immediate value of persistent gases - in the case of mustard gas, for example, evaporation will be very greatly reduced as this liquid freezes at comparatively high winter temperatures. Mustard gas in the frozen state, however, is not by any means inert, as contact with it under there conditions will still produce a burn. If the frozen mustard gas contamination is carried (e.g., on boots) to warmer surroundings it will soon liberate an effective vapour concentration.

Conditions of excessive moisture are also unfavourable to the effective use of persistent gases, as rain tends slowly to destroy them or to wash them away.

The most favourable meteorological conditions for the employment of the two main types of gases are the following:

Non-Persistent gases.

(a) A low wind velocity.

(b), Clear nights (cloudy days and nights are slightly less favourable, while clear sunny days are the least favourable).

Persistent gases.

(a) A low wind velocity.

(b) A high ground temperature.

(c) Absence of heavy rain.

Generally speaking, a clear, still night offers the most favourable conditions for the use of non-persistent gas. At such times the absence of air movements causes the gas to dissipate very slowly with the result that a high concentration is maintained for a long time.

In the case of persistent gases, a high ground temperature is usually the most important consideration, since this will induce rapid evaporation of the gas and the formation of a high local concentration of the vapour.

4. Medical Classification of Gases.

The gases which, so far as can be anticipated, might be used in time of war may be classified as follows:

GROUP 1. Gases which may produce disablement or death.

(a) Vesicants (or "Blister Gases"), such as mustard gas and lewisite. These are substances which, whether in the liquid, solid or' vapour state, will damage any part of the body with which they come in contact. Typical effects of the vapour are acute conjunctivitis, inflammation of the mucous membrane lining the respiratory tract, and burning of the skin varying from erythema to vesication. The effect of the liquid on the skin is severe vesication.

When death occurs after the inhalation of mustard gas, it is usually from a complicating septic bronchitis with bronchopneumonia, while as a result of very extensive skin vesication death may. result from secondary shock or sepsis.

(b) Asphyxiants (or "Lung Irritant Gases"). These gases, which include chlorine, phosgene, di-phosgene and chloropicrin, are essentially lung irritants exerting their main action on the pulmonary alveoli although the upper respiratory passages are effected in addition. They are used primarily as lethal agents, and, in the absence of an efficient respirator, their action usually results in a pulmonary oedema which may be fatal.

(c) Paralysants, such as hydrocyanic acid and hydrogen sulphide. These highly toxic gases were used, but did not prove a success in the last war. More effective methods of liberating them may, however, he found, and knowledge of them from the medical aspect is desirable. In high concentration, both these gases can produce death rapidly through paralysis of the respiratory centre.

GROUP II. Gases used primarily as harassing agents. (These gases may not produce casualties, but they cause temporary distress and compel the wearing of a respirator.)

(a) Lachrymators (or "Tear Gases"), such as chloracetophenone (C.A.P.), ethyl-iodio-acetate (K.SX.) and bromo. benzyl-cyanide (B.B.C.). Even low concentrations of gas given off by these compounds will immediately irritate the eyes, causing profuse lachrymation and intense spasm of the eyelids -symptoms, however, which disappear on leaving the contaminated area. In very high concentrations they may act as acute lung irritants.

(b) Nasal Irritants (or "Nose Irritant Gases"). These are organic arsenical compounds such as di-phenyl-chlor-arsine (DA.), di-phenyl-amine-chlor-arsine (DX) and di-phenylcyano-arsine (D.C.). These solid arsenicals, when suitably dispersed, produce clouds of minute particles which, if inhaled even in low concentrations, will produce symptoms of acute physical distress. These symptoms are distressing gnawing pain in the nose and chest, with lachrymation, salivation and even vomiting. Inferior respirators are penetrated by these fine particles. The symptoms, however, are temporary, and, although alarining at the time, usually subside within an hour after removal from the affected area.

GROUP III. Gases liable to be encountered under war conditions.

(a) Carbon monoxide . This dangerous gas, though not used oflensively as a war gas, is frequently met with in the course of mining and tunnelling operations, in the interior of burning buildings, , and generally wherever combustion occurs in the absence of an adequate supply of oxygen. Typical instances occur in confined spaces following the burst of a high explosive shell, or from the use of slow combustion stoves, charcoal braziers, or internal combustion engines in such spaces. It is a constituent of ordinary illuminating gas, leakage of which may cause serious poisoning. The gas produces its insidious effects through its well known interference with the respiratory functions of the blood. Ordinary respirators give no protection.

(b) Nitrous fumes. These gases are given off by burning cordite, or when detonation of nitro-explosives is incomplete. They act as powerful and very insidious lung irritants, with delayed symptoms resembling those of phosgene poisoning, and it is important to remember that they are often accompanied by carbon monoxide. Respirators generally afford partial protection against nitrous fumes, but none against the carbon monoxide.

(c) Screening smokes. Various chemicals may be used to provide smoke screens for concealing important areas or buildings. Such substances as phosphorus, chlorosulphonic acid, titanium-tetrachloride, and a number of the chlorinatedhydrocarbon series are utilised for this object, while phosphorus may also be used in bombs for incendiary purposes. These smokes are non-toxic in the open, but serious effects may follow the bursting of the bombs at close quarters.

(d) Fumes which may be encountered in fire-fighting. Apart from the risk of encountering carbon monoxide, and possibly nitrous fumes, when fighting fires in 'confined spaces in wartime, an additional danger may arise through toxic gases evolved by fire-extinguishing chemicals. Apart from its possible toxicity, such an atmosphere may be seriously deficient in oxygen.

The order in which these gases are described in the subsequent chapters is that adopted in other A.R.P. Handbooks as being the most convenient for purposes of teaching.

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