Mustard gas (H.) (the "Lost" or "Yellow Cross" of the Germans and "Yperite" of the French) was by far the most effective chemical agent used in the Great War for the production of casualties.

Lewisite, an arsenical preparation developed towards the end of the Great War, is another powerful blistering agent like mustard gas, but, unlike the latter, it has an immediate irritant action both on the respiratory tract and (in the liquid form) on the skin, and is therefore more easily detected.


8. Physical and chemical properties of mustard gas.

A knowledge of the physical and chemical properties of mustard gas is essential to an understanding of its insidious action on the human body. The outstanding features are the following :

Appearance.- In the pure state mustard gas is a clear, heavy and somewhat oily fluid, straw coloured, but in the crude form it is a heavy, dark-coloured, oily liquid.

Odour.-In the absence of chemical methods for the ready detection of mustard gas, the sense of smell is the most reliable guide to its presence. The mustard-like or garlicky odour, though faint in low concentrations, is characteristic of the gas, and it is most important that the smell should be memorized as part of anti-gas training. It is well to remember that mustard gas may produce casualties in concentrations the smell of which may readily escape notice ; also, that the sense of smell tires quickly, and that after a few minutes in a mustard gas atmosphere the smell of the gas may seem to have disappeared.

Boiling Point and vapour Pressure.-The boiling point of mustard gas (2170 C. or 42.30 F.) is high, and its vapour pressure is correspondingly low (0.05 mm. Hg at 100 C., and 0.45 mm. Hg at 400 C.) - hence its slow vaporization at ordinary temperatures and its consequent quality of persistence.

Freezing Point.-The freezing point of pure mustard gas is 14.40 C. (580 F.), while that of the crude variety is considerably lower, viz. 70 to 80 C. (440 to 45.40 F.) - somewhat high freezing points which limit the usefulness of the gas in cold weather, although contact with the frozen material is still a source of danger. It should also be noted that in these circumstances there will be an almost complete absence of the characteristic odour which is often the only indication of the presence of mustard gas.

Density. - Mustard gas has a high specific gravity (1.28 at 150 C. or 590 F.) and, as it is not miscible with water, it readily sinks to the bottom when added to it.

Solubility. Although mustard gas is only very slightly soluble in water (under 1 per cent.), both the liquid and the vapour are freely soluble in animal oils and fats, and it is because of this lipoid solubility that mustard gas finds an easy entry into the skin. Other substances that readily dissolve mustard gas are alcohol, ether, petrol and kerosene, carbon tetrachloride, acetone, carbon disulphide, and many other organic solvents.

Stability.- Both physically and chemically mustard gas is a stable substance; it is unaffected by normal ranges of atmospheric temperature, though simple heat disperses it by hastening evaporation. It is only very slowly hydrolysed by water ; hot water, however, hastens this decomposition, the products of which (hydrochloric acid and thiodiglycol) in ordinary circumstances are practically harmless. For its chemical neutralization strong reagents axe usually required, such as chlorine (as in bleaching powder), potassium permanganate, or other strong oxidizing agents.

Powers of Penetration. - Liquid mustard gas has great powers of penetration, and will soak into all but the most impervious surfaces such as smooth metals, glass and glazed tiles. Like oil it is readily absorbed by clothing, but when small drops of liquid mustard gas fall on clothing any injury which results is as a rule caused by the passage of vapour of mustard gas rather than by the penetration of actual liquid.

Persistence. - Mustard gas is very persistent. Depending on weather conditions it may remain m a liquid and dangerous state for days or even weeks. It may persist under the surface of the ground which appears free of the liquid. Frozen mustard gas may continue to give off vapour slowly for months. As the temperature rises the quantity of vapour given off will increase. The frozen liquid may therefore be carried by boots, etc., to warmer surroundings where it will melt and vaporize.

9. Toxic properties of mustard gas.

Toxicity.- It has already been remarked that, as a casualty producer, mustard gas was the most effective chemical used in the Great War. It is an extremely dangerous substance both in the liquid and in the vapour state, but its action is essentially local, and no general systemic disturbance usually supervenes in the absence of secondary infection. The gas is not selective in its action and any part of the body exposed to it will suffer.

Vapour concentrations.- Atmospheres which contain low concentrations of mustard gas are particularly dangerous, as the comparative absence of smell in such concentrations renders them particularly insidious since the presence of the poison may escape detection and thus cause the exposure to be unduly prolonged.

Insidious characteristics. - The fact that there is no immediate irritation of the skin on contact with the liquid, nor of the eyes and respiratory tract on entering moderate concentrations of the vapour constitutes one of the more serious dangers of this gas, as contamination may be unsuspected. Even when the gas has been detected by its characteristic odour, the sense of smell is soon dulled, or even lost, and the odour will cease to be appreciated. If, however, the respirator is speedily adjusted the odour will be detected whenever the respirator face-piece is raised to "test for gas." It is important to remember, also, that harmful concentrations of the gas can easily be masked by innocuous smokes or by fumes from high explosive, in which case the gas will exert its effects undetected.

Delayed action. - After exposure to mustard gas vapour or contact with the liquid itself no effects are noticed for some time. Signs and symptoms do not begin to appear until after the lapse of some hours, depending on the concentration of the vapour in the atmosphere and the length of exposure thereto. By this time it is too late to ward off the effects of the gas, and casualties result.

Delayed healing. - It has already been stated that the action of mustard gas is local ; the tissues affected are devitalized, they are easily injured by rubbing or pressure, and they are very prone to secondary infection. Where the gas has penetrated deeply, the healing process, even though sepsis be excluded, is very slow owing to damage to capillaries, veins and lymphatics. It is only when the action of the gas is superficial and localized that the condition clears up rapidly.

Sensitivity. - All persons are sensitive to the action of mustard gas, and so far as is known all who have not previously been exposed to its effects possess approximately the same degree of sensitivity irrespective of race or colour.

Acquired hypersensitivity. - In contrast to normal sensitivity it has been found that persons who have suffered injury as a result of exposure to mustard gas may in some cases become hypersensitive to its effects. The condition may be induced by either the liquid or the vapour of mustard gas. It is not possible to say with certainty whether a similar condition may be induced by other types of blister gas, such as lewisite; there is at present no evidence to suggest that this is so.

10. Methods of dispersion of mustard gas.

Of all the known chemical warfare agents, mustard gas is the most versatile in that it will fulfil three objects of gas attacks, namely : (a) to inflict casualties, (b) to harass troops, and

(c) to render ground dangerous to occupy. The delayed onset of the injuries which it produces, however, is a disadvantage from the point of view that it will not immediately arrest the advance of an attacking force.

The method of dispersion will vary with the tactical object the enemy has in view, but his choice will be extensive. Against columns of troops on the march, or against large concentrations of troops or transport, air spray will be an effective method of inflicting casualties, whereas in position warfare, against personnel manning trenches or other fixed positions, mustard gas shell or other projectiles will probably be chosen, especially if surprise can be coupled with intensity of fire.

In the case of buildings, encampments and industrial centres generally, mustard gas air bombs will be more effective in producing results, especially if supplemented by high explosive or incendiary bombs.

For harassing purposes almost any method of mustard gas contamination may be utilized; similarly, a heavy contamination of an area by means of air bombs, gas containers or shell fire may be successful in rendering such a position untenable or dangerous to occupy. With this object, also, gas "booby traps" may be set by a retreating enemy, while living quarters, dug-outs, trenches, etc., may be heavily contaminated by him before withdrawal by the use of hand contamination bombs, contact or delay action mines, containers fired by time fuses, etc.

11. Dangers to be anticipated from liquid mustard gas.

The great majority of mustard gas casualties in the Great War were caused by exposure to the vapour emanating from collections of the liquid deposited by shell. In the absence of special protective clothing, mustard gas burns are inevitable unless the normal clothing be removed within a matter of minutes. The appearance of these burns will be delayed, and they will be slight or severe, localized or extensive, according to the number and size of the drops of the liquid on the clothing.

Gross contamination of the body with correspondingly severe results may also occur from splashes of liquid mustard gas due to proximity to a bursting mustard gas shell or bomb.

A more insidious danger from the liquid is represented by contaminated material which may require handling where contamination may not be suspected; or, again, when mustard gas in the frozen state is present, and, owing to the reduction of vaporization under such conditions, it is unwittingly handled on contaminated material or otherwise brought into contact with the skin.

A number of casualties have in the past occurred through accidental splashes of, or contact with, the liquid in factories and shell-filling depots.

12. Lesions produced by liquid mustard gas.

(1) Skin burns due to the liquid.

(a) On bare skin.- It must again be emphasized that although liquid mustard gas is a direct irritant to the skin, the sensory irritation is not immediate. Its high lipoid solubility enables it to penetrate tissues rapidly, but hours may elapse before the clinical signs make their appearance.

Penetration is rapid, and this rapidity is enhanced by an elevated temperature of the skin or under hot weather conditions; for this reason persons in the tropics may appear to be hypersensitive to the gas.

The initial signs and symptoms of a typical mustard gas burn are an erythema at the site of contact; the capillaries become engorged, and oedema, with thickening of the skin, supervenes. The erythema deepens, and in severe cases may even assume a livid hue: a pale, parchment-like area makes its appearance in the centre of this erythematous zone, and a vesicle, tensely filled with clear yellow serum, gradually forms. This vesicle is the result of an inflammatory exudation of fluid which may continue for several days, according to the depth of penetration of the liquid gas; the exudate, however, contains no actual mustard gas.

If the liquid contamination of the skin be widespread, as in a smear or splash, the erythema is followed by the appearance of numerous small vesicles which gradually coalesce to form large blebs, the underlying area being raw and oedematous, such blisters may continue to develop in crops for several days after contamination.

There is no evidence that any of the liquid mustard gas finds its way into the general circulation. Apart from the itching - which may be severe where warm, moist parts of the body are affected - there is very little or no irritation except some stinging while vesication is developing, and no pain follows the appearance of the latter. The danger of sepsis following, however, is a real one, especially if the blistered area be extensive, as the tissues affected are devitalized, and the blood supply is impaired.

In the absence of secondary infection no constitutional disturbance is usually noted, and primary shock is absent. Healing, however, is a slow process (partly because the blood supply has been damaged, and partly on account of residual mustard gas or its derivatives in the tissues).

The resulting scar, which is soft and pliable, often assumes a coppery pigmentation which disappears after a time.

(b) On clothed skin. - Drops of liquid mustard gas on clothed areas of the body act by virtue of the high concentration of vapour evolved, the warmth of the underlying skin naturally assisting the process. A gross contamination of the clothing, on the other hand, such as may be produced by splashes or by accidental spilling, may result in actual contact of the liquid with the skin, when the action of the vapour would be superadded to that of the liquid.

All ordinary clothing is pervious to liquid mustard gas ; but it is obvious that penetration will be much more rapid in the case of the single thin cotton garment of tropical and sub-tropical countries than with the multiple layers of woollen clothing worn in temperate climates. If the garments be damp or wet the rate of penetration of small drops of liquid mustard gas is somewhat hastened and skin bums may result.

(2) Eye burns due to the liquid.

Contamination of the eye by spray or splash represents one of the gravest dangers to which the body can be subjected in the presence of liquid mustard gas, as permanent damage will result.

The degree of discomfort which immediately follows contact of the liquid with the eye may be slight, and usually subsides; symptoms often begin within half an hour, however, and within an hour or two the eye is inflamed and the eyelids are swollen and painful.

The clinical signs are ushered in by profuse lachrymation and conjunctivitis, and the condition develops with great rapidity. The eyelids become painful, swollen and greatly thickened by oedema, the palpebral conjunctiva is red and oedematous and the cornea develops opacities, while the ocular conjunctiva becomes congested and shows signs of ulceration. Intra-ocular tension is increased, pain and headache are severe and a muco-purulent secretion exudes from the closed eye. Photophobia and blepharospasm may be extreme, and great difficulty is encountered in examining the swollen and painful eye.

As a result of actual liquid mustard gas contamination of the eye large areas of the conjunctiva may readily be shed, and partial or complete loss of vision may result from the extensive ulceration and scarring.

13. Protection against liquid mustard gas.


In view of the penetrative properties of liquid mustard gas it is necessary, for bodily protection, to adopt materials which are, as far as possible, impervious to the liquid. The choice of such materials is narrow, nor do they conduce to bodily comfort; hence they must take the form of additional equipment for use when necessity arises.

Protection against liquid mustard gas implies special protection for the eyes and general protection for the skin, both bare and clothed. The eyes may be safeguarded by the use of special eye shields or of a suitable respirator, while the skin can be adequately protected by garments, gloves and footwear made of materials of proved resistance to penetration by mustard gas.

It may be necessary to remark here that no wearing material as yet discovered is completely impervious to mustard gas; penetration by the liquid, or by the vapour evolved therefrom, is only a question of time if no steps be taken to neutralize or remove the contaminant. Hence the term "mustard proof" in connection with protective garments is only a relative one, and merely means that protective clothing is more resistant to penetration by mustard gas than ordinary garments.

Once they become contaminated these protective materials are a potential danger, both to the wearer and to his neighbours, until freed from contamination. Special care, therefore, should be taken not to spread contamination by wearing them in enclosed spaces such as dugouts, living-rooms, public conveyances, etc., nor to continue wearing them after the necessity for doing so has disappeared.

An additional protective garment - apron, anti-gas - has been designed for the Auxiliary Services generally, e.g. mustard gas factory workers, undressers in decontamination stations, etc. This resembles an operating gown and consists of an apron with full length sleeves; it covers the front of the body and fastens by tapes at the back.

14. Dangers to be anticipated from mustard gas vapour.

In the absence of visible liquid mustard gas the sense of smell is the most reliable guide to the presence of mustard gas vapour. It must be remembered, however, that this vapour can be harmful in concentrations that may not be readily noticed by the sense of smell; also, that the sense of smell for mustard gas vapour tends to become dulled quickly, when the danger may no longer be appreciated.

The cumulative effect of repeated small doses of the vapour is another insidious danger. A lack of gas discipline, a natural impatience engendered by the prolonged wearing of a respirator, or dire necessity in emergencies may influence men, exposed to mustard gas vapour, to remove their masks occasionally for short periods: on each such exposure they will receive a dose and a series of these may ultimately produce casualties.

The vapour concentration necessary to produce effective results need not be of a high order. When it is realized that one hour's exposure to a concentration of one part of mustard gas vapour in one million parts of air is sufficient to incapacitate an unprotected man for about two weeks through conjunctivitis, it will be seen that a very minute quantity of liquid mustard gas in a closed room may easily produce casualties.

Again, the possibility of the odour of mustard gas being masked by smokes or high explosive, and its lack of immediate sensory irritation in effective concentrations, are additional dangers which well trained personnel will have to bear in mind.

The degree of severity of mustard gas vapour casualties varies with the concentration and the period of exposure. The least severe case may show only light conjunctivitis, with almost no erythema of the skin and only a slight hoarseness of the voice; the most serious, on the other hand, may present a picture of the most profound illness, usually with widespread skin burns, severe eye effects and damage to the respiratory tract. A moderately severe case of exposure to the vapour when quite unprotected will present a typical appearance in 24 hours, with eye symptoms predominating; general reddening of the skin occurs, most marked in the genital region where the excoriation of the skin may cause irritation, while, at about the same time the respiratory begins to show signs of involvement by a partial loss of voice and by a troublesome cough.

In the Great War, the death rate among well disciplined troops who were provided with effective respirators was low, approximately 2 per cent of the mustard gas casualties, but the death rate when respirators were not worn was about 50 per cent. Fatal cases were almost unknown the first 24 hours after exposure. Death occurred at any date from the second or third day in the most severe cases to the third or fourth week in the more lingering ones, the highest death rate being at the end of the third or fourth day after exposure and almost always due to secondary broncho-pneumonia.

The main features of mustard gas vapour casualties may be briefly summarized as follows:

(a) An insidious onset, with a latent period of two to 48 hours according to the concentration of the gas and the duration of exposure.

(b) Injury to the eyes, varying from simple conjunctivitis of a temporary nature to a severe keratitis and grave secondary septic complications.

(c) Laryngitis, involvement of trachea and bronchi, and possibly necrosis of the mucous membrane leading to severe bronchitis or broncho-pneumonia.

(d) Early nausea or persistent vomiting, accompanied by epigastric pain.

(e) Erythema of the skin - early in the case of exposed areas or of hot, moist surfaces-which may proceed to vesication or excoriation, and may be followed by secondary septic infection.

(f) Slow healing of the blistered, devitalized areas and pigmentation of the ensuing scar.

15. Nature of casualties from mustard gas vapour.

(1) Action on the eyes.(See plates on eyes)

On exposure to mustard gas vapour no discomfort is felt, and a latent period, which may be long, intervenes before symptoms appear.

After a short exposure to dilute vapour, soreness of the eyes, slight lachrymation and blepharospasm develop after 5-48 hours. The lid margins become reddened and swollen, and the conjunctiva congested especially in the palpebral aperture (Plate EyeB). The cornea may lack lustre owing to epithelial oedema. The prognosis is good and the condition will clear up in 7-14 days with no complications.

Moderately severe lesions result from longer exposure. Pain, lachrymation and blepharospasm are more severe. The lids are very swollen, the discharge profuse but watery unless secondary infection occurs, and the cornea dull and lustreless (Plate eyeA). Depression and fear of blindness may be a feature. The eye should be open in four to five days, but corneal oedema may persist for a further ten days. The prognosis is good, with gradual recovery in three to five weeks, but a few cases may at a later date develop a "delayed" vascularised keratitis.

Severe lesions are caused by long exposure to more concentrated vapour. The onset of symptoms may occur within two hours, and pain, swelling of the lids, lachrymation and blepharospasm are intense, the latter often making it difficult to examine the eye. If the lids can be separated the palpebral conjunctiva and the non-exposed parts of the bulbar conjunctiva will show marked congestion and oedema, whilst the exposed (interpalpebral) part of the bulbar conjunctiva will appear pale and bloodless (Plate eyeA). The cornea will be hazy and lustreless, and will show obvious desquamation of its epithelium. In addition there will be iritis, with congestion of the iris and contraction of the pupil.

With actual liquid contamination the damage is still more severe addition to the desquamation of the corneal epithelium, large the conjunctiva may be shed.

Should secondary infection occur scarring of the cornea may be the end-result, but even in cases in which this does not occur "delayed" and vascularisation of the cornea may cause the case to drag on for years. Such severe cases may therefore take months to recover, and in some cases symptoms may persist for years.

In the last war eye casualties were caused, more often by vapour than by liquid. Of these, 75 per cent. were mild and recovered on the two weeks; 15 per cent. were of intermediate severity and recovered in four to six weeks; 10 per cent. were severe with corneal changes, requiring two to four months for recovery, though only a small minority sustained total loss or impairment of vision.

(2) Action on the respiratory tract.

The toxic effects of mustard gas vapour on the respiratory tract are shown by an early rhinitis (almost simultaneous with the onset of the discharge of a profuse accompanied by sneezing and the discharge of a profuse watery secretion, soon to become muco-purulent.

The larynx is usually affected early, and hoarseness and aphonia are frequent. The laryngitis may be mild if exposure has been limited to a low concentration, but oedema and even sloughing of the vocal chords may follow exposure to a high concentration.

In a severe case, the laryngeal inflammation tends to be reproduced in the trachea and bronchi, when the dry irritating cough, originally complained of at the onset of the laryngitis, is replaced by the loose cough accompanied by profuse mucopurulent expectoration and pain behind the sternum. A rising temperature and pulse indicate the onset of a severe bronchitis which may be complicated by sloughing of the inflamed tracheal mucous membrane; secondary infection of the latter soon leads to the development of a broncho-pneumonia with cyanosis. Rarely, abscess of the lung, bronchiectasis, or even gangrene of the lung may occur - not as a direct result of the gassing by mustard gas vapour, but of the secondary bacterial invasion which follows.

In the great majority of cases, however, the lesion is confined to a bronchitis which clears up in the course of a month or six weeks, leaving no after-effects.

(3) Action on the skin. (See plates skin 1 and 2.)

Before describing the effects of mustard gas vapour on the skin it may be useful to mention some of the factors that influence the penetration of the gas or modify the severity of its action.

As in the case of liquid mustard gas, the vapour owes its penetrative powers to its ready solubility in the lipoid tissues of the skin. The degree of skin burning which follows is accentuated if the exposed skin area be a highly sensitive and tender region such as the scrotum, or if it be a surface which is subjected to constant friction, as is the case in the neck, the wrist and the ankles.

If the exposed skin surface be bare, the attack of the vapour will be direct, and the result more rapid than if the skin be clothed. This temporary protection of clothed areas is due to the fact that ordinary porous clothing material absorbs the vapour and retards its access to the skin; but if such clothing be worn beyond the period of actual exposure, or if the exposure be prolonged, the vapour retained by the clothing will increase the severity of the resulting skin burns.

This temporary protection varies in duration according to the nature, texture, thickness and degree of humidity of the clothing. Thus, a thin openwork cotton garment in close apposition with the body surface will not greatly retard the access of the vapour to the skin, whereas thick close-woven material, such as serge and woollen clothing generally, will definitely do so, and may even save the area from burns provided that it be discarded on leaving the contaminated area. Again, damp and sweaty clothing will absorb more mustard gas vapour than the same clothing when clean and dry.

After the lapse of the usual latent period, which may vary from two to 48 hours after exposure to the vapour of mustard gas, an erythematous blush appears over the affected area and gradually deepens in intensity until the skin looks scorched.

This redness is not unlike the eruption of scarlet fever, and is usually accompanied by only a slight degree of irritation. The erythema is most marked on the skin areas which are hot and moist ; dense tissues like the scalp, the palm of the hand or the skin of the heel usually escape unless the concentration of the vapour be high and localized to that area, as, for example, from drops of liquid mustard gas on a cloth cap.

The affected area soon begins to show superficial blistering in the form of small vesicles which rapidly coalesce to produce large blisters full of a clear yellow serum; on evacuating this fluid and removing the overlying epithelium, a raw, red, weeping surface is exposed.

As a rule, vesication is complete by the second day, but blisters may appear in crops for days following exposure, even though all contaminated clothing be discarded at an early stage. Systemic disturbance is absent, unless the burns are extensive and severe; interference with sleep, however, may be caused by the distressing itching which may accompany the developing burns.

Very mild cases may show simply erythema, followed later by pigmentation with scurfy desquamation, the "blister" stage being absent.

In severe cases the erythema may deepen to a dusky, almost violet, tint, oedema of the skin is marked, and blisters appear over the dark background overlying a deep red or haemorrhagic base. Such blisters progress slowly, and are very prone to sepsis owing to the serious devitalization of the tissues; ulceration is liable to spread beyond the limits of the blister, and healing is very slow. If sepsis occurs it adds to the severity and duration of all lesions ; the necrosed tissues form an excellent medium for pathogenic organisms, and death may result if extensive or deep burns are thus affected.

The healing of an uncomplicated vapour burn is more rapid than one due to liquid mustard gas, but a common feature of all mustard gas bums is the long time they take to heal. The chemical irritant seriously damages the vitality of the affected tissues, and all processes of skin repair are delayed.

The healed stage is characterized by a brownish or coppery pigmentation of the epithelial layers in the areas previously affected by the erythema. This staining is superficial, and usually disappears with the normal desquamation of the superficial layers of the skin.

As a rule, serious after-effects are absent, and the scars resulting from vapour burns are shallow, but a chronic eczematous condition or a generalized furunculosis may, rarely, follow such burns and prove obstinate to treatment.

(4) Other effects of mustard gas vapour.

Apart from its direct action on the eyes, the respiratory organs and the skin, . and mainly owing to the skin, mustard gas vapour may indirectly, and mainly owing to secondary infection, produce signs and symptoms in more remote organs of the body.

(a) Alimentary tract.- It has already been mentioned that an early nausea, or even vomiting accompanied by epigastric pain, often occurs in poisoning by mustard gas vapour. This effect is due to the swallowing of saliva or nasal secretion impregnated with the gas. Although it may prove obstinate during the first day, it. rarely persists for more than 48 hours; similarly, the accompanying epigastric pain is of short duration, and the intestines are not usually affected. There are no lasting after effects, but a functional condition of persistent nausea or vomiting has been observed occasionally.

(b) Urinary tract.- Traces of albumen have been found in the urine of early fatal cases. most probably due to congestion from circulatory weakness and not as a result of the action of the gas on the kidneys. It is only in the late stages of fatal cases, and particularly in those instances where widespread septic burns have occurred that renal complications have been noticed, such as an acute haemorrhagic nephritis. Pain on micturition, however, and even retention of urine may result from a local oedema and vesication of the penis.

(c) Circulatory system - Blood changes are not met with, and any alteration in the leucocyte count is due either to pulmonary complications or to sepsis of the skin burns. Apart from the effects of the general toxaemias of pneumonia or sepsis, no primary changes occur in the cardiac mechanism, but a functional condition of effort syndrome is not uncommon as a result of the gassing.

16. Protection against mustard gas vapour.

The general remarks on protection against liquid mustard gas apply equally well in the case of mustard gas vapour, except that most goggles afford no protection against the latter, and a respirator must be worn if the eyes are to be safeguarded.

A well fitting respirator will effectively protect the eyes, the respiratory tract and the skin of the face, but, in the absence of other protective equipment, the rest of the body is open to attack.

It has already been mentioned that ordinary porous clothing, especially thick, dry woollen garments, affords some measure of safety if worn only for the period of a short exposure to the vapour. With regard to the complete oilskin outfit employed in decontamination work it has been mentioned that, owing to its stiff and impermeable character, the wearer's movements give it a bellows-like action when bending or doing manual work. Contaminated air is thus sucked inside the garment through any available channel, with the result that, with vigorous work, it is only a matter of time before the atmosphere inside the suit becomes as dangerous as that outside.

Where circumstances permit, the risk of vapour burns under these conditions may be lessened if the impervious garments be freely ventilated at frequent intervals in an atmosphere uncontaminated by the gas. Such favourable opportunities, however, are not likely to be present where the contaminated area is extensive, or when duties of an urgent nature are being carried out.

Protection against mustard gas vapour is, therefore, even more difficult to achieve than protection against the liquid, and all contaminated garments must be rapidly changed and decontaminated.

17. Treatment of personnel contaminated by mustard gas.

In view of the rapid penetration of the skin by mustard gas, it is essential that every person should be familiar with any local measure that may prevent, or at any rate lessen, the lesions produced by the gas, and should have the means at hand for carrying out this preventive treatment himself, as far as it is possible for him to do so. Treatment may therefore be discussed under two headings, namely: (1) Preventive, and (2) Curative.

(1) Preventive treatment.

It has already been seen that the early detection of mustard gas vapour and the rapid adjustment of the respirator will efficiently safeguard the eyes and the respiratory system, leaving, however, the rest of the body open to attack. It has also been noted that the special protective clothing of the oilskin type, together with rubber boots or overboots of oil-dressed fabric will give an adequate means of protection against liquid mustard gas, but will offer only a brief period of safety against the vapour. Similarly, it should be remembered that ordinary garments afford little, if any, protection against either liquid or vapour, and that, after contamination, they are a definite source of danger not only to the wearer but also to others.

Preventive treatment, therefore, consists essentially in the speedy and complete removal of all contaminated clothing and in freeing the skin from the contaminant, whether liquid or vapour. Should a Thomas's splint have to be applied special care will have to be taken not to restrict the circulation through the foot if it is necessary to remove the boot owing to its contamination by liquid mustard gas.

Exceptions to, or modifications of, this general rule may be met with, as, for example, in the case of a small localized liquid contamination of the bare hand, or after exposure to a low concentration of the vapour, when prompt local cleansing of the skin or a change of clothing respectively will suffice. Each case will have to be considered on its merits; but, whatever the type or extent of the contamination, speed is the essence of all preventive treatment. Delay of a minute or two in the case of liquid contamination, or of 10 to 15 minutes following exposure to the vapour, before cleansing of the skin is undertaken may result in definite burns of the affected areas.

When the skin is hot as a result of exercise, and in hot or tropical countries, the results obtained by all preventive methods of decontamination of the skin are inferior to those obtained when the skin is cool and dry so the need for prompt action is even greater under these conditions.

After removal of all contaminated garments, which must not be used again until decontaminated, preventive treatment of the skin should be undertaken without delay. The choice of methods is not large, but one or more of them should be readily available at all times, even under war conditions in the open field, and the best preventive treatment to adopt is the one which is the most readily available.

In the event of liquid mustard gas contamination, cleansing of the skin may be effected by--

(a) Bleach treatment.- Thoroughly rubbing in, for one minute, either bleach ointment (ointment, anti-gas, No. 1), or aqueous bleach paste, over the affected area. This procedure chemically neutralizes the mustard gas.

The ointment is the more portable of the two, and the more readily available to all personnel in the field. As a first step in the prevention of bums, when the contamination is small and localized, thorough rubbing with the ointment is the method of choice. For extensive contamination by the liquid, however, a thorough inunction with aqueous bleach paste will be found more easy of application.

When the operation is completed, the ointment should be wiped off, or, if the aqueous paste was used, the affected part should be flushed with water - the object being, in each case, to remove surplus bleach from a potentially injured area. Bleach will destroy free mustard gas quickly, but it will also irritate the skin if left in contact with it. Care must be taken to prevent access of the bleach to the eyes. Bleach ointment or paste should not be used if an erythema has already developed as it will aggravate the condition.

Actual vesication of the skin by drops from mustard gas spray may be avoided if preventive treatment be undertaken within a minute or two after contamination. Even though the delay be longer, bleach will still be the method of choice so long as liquid mustard gas is visible on the skin, as it will mitigate the severity of the resulting burn.

Bleach ointment (Ointment, anti-gas, No. 1) is made by mixing equal parts, by weight, of "supertropical" bleaching powder (i.e. "Bleaching Powder, 30 per cent.") and white petroleum jelly, while the aqueous bleach paste consists of "supertropical" bleaching powder mixed to a creamy consistency with water - roughly, one part of the powder to one or two parts of water by volume. The ointment keeps well, while the aqueous paste retains its effectiveness in temperate climates for several weeks if it be stored in enamelled containers with well fitting lids. Bleaching Powder is ordinary chloride of lime, while supertropical bleach is ordinary bleaching powder stabilized by the addition of quick-lime and fulfilling certain conditions of stability and chlorine content.

Ordinary bleaching powder is more irritating to the skin than the supertropical variety, but in the absence of the latter it is quite suitable for preventive treatment when made up as an ointment with while petroleum jelly, or into a paste with water, provided prolonged storage is not contemplated.

The use of white petroleum jelly is specified since yellow petroleum jelly ("vaseline") in contact with bleach may generate heat and may even lead to combustion on storage. The latter may, however, be used in emergencies for immediate application.

The mixing of ointments should be thorough and uniform and in the proportion (by weight) of one part of bleach to one of white petroleum jelly. If the mixing is to be carried out in bulk, the employment of a mill is advocated in order to ensure the required uniform consistency.

(b) Ointment, anti-gas, No. 2 is composed of Chloramine-T in a vanishing cream base. It is used like ointment, anti-gas, No. 1, but need not be wiped off. The ointment can be rubbed into the hands as a prophylactic against mustard gas and lewisite, but its use for this purpose on more tender parts of the body is contra-indicated as it has an irritant action on the skin.

(c) Repeated swabbing of the contaminated area with petrol, methylated spirit, kerosene, carbon tetrachloride (Pyrene liquid) or other solvent of liquid mustard gas. It is important to remember that these solvents do not destroy the gas, but merely dissolve it ; hence the swabbing must be confined strictly to the contaminated area, and must be repeated.

This method is effective if carried out by skilled individuals, and solvents are within easy reach; certain precautions, however, are necessary. Oilskin or rubber gloves must be used if available; otherwise, the swab should be only partly moistened with the solvent, and it should be held between finger and thumb by the dry portion or preferably in forceps; the wet portion is then applied to the contaminated skin so as to soak up the liquid contamination, care being taken that none of the solvent runs over the skin of either the subject or operator; the contaminated swab is then discarded and the process is repeated for several minutes with fresh swabs, or as long as the characteristic odour of the gas persists on the skin. Thorough washing with soap and water, if available, will complete the treatment; the contaminated swabs must, of course, be destroyed by burning or burying and the gloves and forceps decontaminated.

One disadvantage of this method in the hands of unskilled persons is that the solvent is apt to "run" on the skin and cause burns on areas comparatively far removed from the original site of contamination; a further disadvantage is the liability of the operating fingers to become contaminated in the absence of gloves. Employed with care and intelligence, however, the method is valuable in emergencies such as may occur in aerodromes, among mechanized transport, and in other situations where mustard gas solvents are readily available.

(d) Scrubbing with soap and water, using hard soap and frequent changes of water. This process does not destroy the mustard gas, but merely removes it in the lather; the scrubbing must, therefore, be confined to the contaminated area, and the operator's hands should be safeguarded, if possible, by suitable gloves.

If the liquid contamination be small, localized and of known situation, this is an effective method of removing it if carried out promptly. In any case, vesication of the skin is usually prevented if the treatment is not delayed beyond five minutes, though an erythema will probably result.

With a gross contamination, or when the drops of liquid mustard gas are multiple, the results of scrubbing with soap and water are unfavourable, as it is difficult to avoid spreading the contaminant in the soapy lather to surrounding areas. In these circumstances bleach treatment is the method to adopt if available.

Where erythema has already begun, washing off with a solvent should be used, as the other methods are themselves somewhat an already inflamed skin.

Should it not be possible, however, to deal with such a contamination until some time has elapsed, thorough washing should still be carried out at the first available opportunity in the hope of mitigating the degree of burning.

After contamination with the vapour of mustard gas, i.e. after exposure to an atmosphere contaminated with the gas, or when the outer clothing has been sprayed, or has otherwise come in contact with the liquid form of the gas, preventive treatment should consist of a rapid removal of all equipment, followed possibly by a thorough washing of the whole body surface with soap and water, preferably under a shower.

Preventive treatment of special areas: apart from the skin surfaces, the only other areas to which preventive treatment can be extended are the eyes and the nasal and pharyngeal mucous membranes.

Contamination of the eye by liquid mustard gas presents a very serious problem. In order to reduce this risk to a minimum eye-shields have been issued as a protection against surprise by aircraft spray. If these eyeshields are properly worn droplets of mustard gas should not gain access to the eyes. If, however, in the absence of an eyeshield, a drop of liquid mustard gas does fall into the eye the resultant injury can be lessened, provided that the drop is small, if the eye can be immediately flushed out thoroughly with water from a water-bottle or any other available source. With a large drop flushing will do some good, but it will probably fail to prevent serious injury to the eye and permanent impairment of vision. The treatment must therefore take precedence over other decontamination measures, e.g. the use of Anti-Gas ointment.

In view of the very serious results that may ensue from the penetration of liquid mustard gas into the eye, and the obvious difficulty of flushing out the eye immediately in the field, too much stress cannot be laid on the importance of wearing eyeshields.

If inflammation of the eyes is caused by prolonged exposure to the vapour of mustard gas emanating from the ground or other contaminated objects, such irrigation cannot be expected to have much effect since the poison has been slowly absorbed over a considerable period of time. Since, however, aircraft spray must be regarded as a potential weapon and there may be uncertainty in any given instance whether exposure has been to spray, vapour or to both, the initial routine treatment should be irrigation with water for three to five minutes. This treatment can do no harm, and in some cases it may help to reduce the subsequent effects: it should, therefore, never be omitted.

(2) Curative treatment.

The first essential in the treatment of mustard gas casualties is the prevention of further infection from contaminated clothing: it will be necessary, therefore, to strip the patient of contaminated clothing and to wash the entire body surface, employing frequent changes of soap and water. This must be done as soon as the eyes have been flushed out with water or saline.

The second essential is to relieve immediate symptoms and to prevent the septic infection of possible lesions. The latter object is very important, for experience has shown that sepsis readily supervenes in areas devitalized by the action of mustard gas.

(a) Treatment of the eyes. - The value of initial flushing out of the eyes with water or saline has already been considered.

By the time the casualty is seen there is sure to be some degree of conjunctivitis, accompanied by swelling of the eyelids, and photophobia. It is important to open the eyelids so as to let the man see that he is not blind. Fear that the sight has been permanently affected can be very real, and reassurance on this point will have an important psychological effect.

After this, instil a few drops of a non-irritating antiseptic and repeat this four times daily. Experiments on animals suggest that ALBUCID SOLUBLE (2.5 per cent. solution) is probably the best drug to use for this purpose. ALBUCID SOLUBLE is one of the sulphonamide derivatives which forms a neutral solution with water. Stronger antiseptics should never be used, as they have been proved to be ineffective and may do harm.

Albucid will be supplied in 5 c.c. ampoules of 30 per cent. solution. The contents of one ampoule diluted to 60 c.c. will give a 2.5 per cent. solution. (Editor's note: Albucid was not available in 1918 - this book was published in 1940.)

Never use repeated irrigation of the eyes, i.e. never irrigate except at the onset unless the discharge is very copious. Experimental work has shown that repeated (e.g. 2 hourly) irrigation is a bad form of treatment and increases the severity of the lesion. If the discharge is very severe, wash it out with normal saline night and morning before instilling Albucid.

If blepharospasm. is sufficient to close the eyelids completely, instil 1 per cent. atropine drops and get the case seen by an ophthalmic surgeon at once for two reasons :

(i) So that mild cases may be diagnosed as such and not transferred as severe casualties. This will lessen the development of "functional"cases and therefore reduce the drain on the fighting troops.

(ii) So that severe cases may be diagnosed as such and thus complications be avoided.

Cocaine should not be used to relieve pain since it has a deleterious effect upon the corneal epithelium which is already damaged by mustard gas.

The eyes should not be bandaged nor closely covered since free drainage of the discharge is essential, but a forehead shade is permissible. Such a shade can be easily improvised from brown paper or other material.

Never instil liquid paraffin (or other oily drops) during the first few hours, but after that it may be used to prevent the lids from becoming adherent.

Many of the casualties caused by exposure to vapour are likely to be mild. None the less such casualties may at first be unable to see owing to the swelling of the eyelids and pain, and the early photophobia, which has a genuine cause, may be succeeded by a functional photophobia which unduly protracts convalescence. If this is to be avoided and the mild cases returned to full duty without avoidable delay, it is essential to remove the eye shade as soon as possible and to make the casualty confident that he need fear no permanent injury to the eye nor impairment of vision. General tonic treatment, and suitable exercise that will keep the casualty from brooding on his condition, will hasten his recovery.

Mustard gas has, as the experience of the last war showed, a very high casualty producing value, and undue wastage of the fighting troops can only be prevented by taking trouble over the treatment of the milder casualties so as to minimize the time spent either in the hospital or the convalescent camp.

It is, of course, the casualties who have been exposed for a considerable time to a heavy concentration of vapour, and in particular those cases in which a drop of liquid mustard gas has entered the eye, that offer the most difficult problem, and it is these cases which demand the most careful attention of the ophthalmic specialist from the start if the effects of the grave injuries which are so likely to result are to be minimized.

(b) Treatment of the respiratory tract.-The early rhinitis is usually overshadowed by the condition of the eyes; should there be pain and distressing discharge, it may be treated with copious warm douches of sodium bicarbonate in 5 per cent. solution several times daily. In the rare cases where a persistent muco-purulent discharge, associated with ulceration and occasionally with epistaxis, is long continued, an astringent lotion containing zinc sulphate gr. 1 with boric lotion oz. 1, will be found helpful.

Laryngitis and tracheitis. - The laryngeal irritation is best dealt with by topical treatment such as laryngeal spraying with medicinal liquid paraffin, or by the inhalation of steam from a pint of boiling water containing a teaspoonful of a mixture of menthol grs. 10 in Tinct. Benzoini Co. oz. 1. The harsh, dry cough may also be eased by breathing through a perforated metal mask (Burney Yeo) containing a pad of gauze moistened hourly with drops of some volatile antiseptic mixture such as:

Menthol . . .. .. gr. 20

Chloroform .. .. min. 60

Creosote .. .. .. ,, 60

01. Eucalypti .. ,, 20

Liq. Iodi. Mitis ,, 30

Sp. Vini. Rect. .. to one ounce.

The menthol in such a solution will help to alleviate the paroxysmal coughing which may otherwise result if such an anaesthetic as simple ether has to be used to allow operative treatment of an accompanying wound.

Broncho-pneumonia. - As the majority of deaths from mustard gas in the Great War were due to secondary infections of the respiratory tract, treatment should be directed, from the outset, towards combating the bacterial invasion of the bronchi.

As a preliminary step against extraneous infection, all cases of mustard gas poisoning in which the respiratory tract is involved must be kept apart from other patients suffering from infective pulmonary disorders; they should, if possible, be segregated in special wards, and the onset of broncho-pneumonia in one of them should entail his isolation.

In the various stages of the broncho-pneumonia, treatment is symptomatic and follows the recognized rules of procedure, including the employment of expectorants where the muco-pus is tenacious and difficult of expulsion. It may be stated here that the prophylactic venesection advocated for phosgene cases, which is of value in the early treatment of pulmonary oedema, has no place in the treatment of mustard gas cases, though occasionally it may be indicated at a later stage to relieve the right heart of embarrassment and cyanosis induced by a diffuse bronchopneumonia. The same may be said of oxygen therapy, which, although essential in the pulmonary oedema caused by phosgene, is only indicated occasionally and at a late stage in mustard gas poisoning when cyanosis is established as the result of grave and widespread pulmonary damage.

(c) Treatment of the skin. - As in other regions of the body, sepsis following skin contamination is the most potent factor in delaying the satisfactory healing of skin burns. When it is remembered that the skin surfaces of troops in the field under war conditions are unavoidably dirty, and that mustard gas penetrates, and in so doing devitalizes the skin. it is obvious that early preventive treatment is of paramount importance inasmuch as it will lessen the severity of the skin burns and reduce the risk of sepsis, and that any curative treatment should have some antiseptic value.

As a preliminary to all local treatment it is essential to cleanse the skin as thoroughly as its damaged condition permits, and to clip short all hair, if any, on the affected area. It may be useful to repeal here that the application of bleach in any form to a skin which is already showing signs of damage will aggravate the ensuing burn. It must also be noted that skin surfaces damaged by mustard gas are exceedingly susceptible to trauma, and that even the continued pressure of an ill-fitting bandage may lead to an extension of the damage.

As treatment will vary according to the nature and degree of the burns, it will be best to consider these in detail:

(i) Erythema: Mild cases which do not proceed beyond an erythema heal spontaneously, with possibly some desquamation and pigmentation. They may be compared with sunburns in severity and discomfort, and clear up just as readily. If the skin is unbroken a mildly antiseptic dusting powder may be applied. A suitable formula is zinc oxide, boric acid and chalk in equal parts.

(ii) Vesication: It is this stage that will afford a critical test of successful treatment through the elimination of secondary infection, as the devitalization of the tissues in this case is much more profound.

Any available cleansing treatment in use in surgical practice will suffice for the undamaged skin surrounding the burn itself. In the last war extensive use was made of Eusol and of Dakin's solution for the treatment of bums, but they are too painful for continued use on raw surfaces. Picric add and similar powerful germicides are undesirable because of the toxic symptoms that may follow their absorption, while ointments and pastes are, as a rule, contra-indicated because of their tendency to seal up discharges; for the same reason powders are undesirable as they are apt to produce crusts which retain the discharge.

When discrete, circumscribed blisters make their appearance they should be evacuated, under aseptic conditions, by means of a hypodermic syringe or a sterile needle, gentle pressure being applied, if necessary, upon the walls of the blister with a sterile swab to ensure complete evacuation ; the intact epithelium should then be allowed to collapse and seal down the raw, sensitive surface underneath. This evacuation of fluid from blisters may have to be repeated, in some cases, owing to the continued oozing of serum from the raw area. The further treatment of these circumscribed vesicles consists in the application of dry sterile dressings.

Larger blistered areas require more elaborate treatment. The lesion itself, and a large area of the surrounding skin which may ultimately show damage, should be cleaned with a non-irritating antiseptic, e.g., Dettol (20 per cent. solution). The blisters, unless already broken, should be punctured when they become tense. Since the exudation in such cases is very copious, it is no good using a tanning treatment at the start, as any coagulum formed will be floated off by the continued exudation, and it will be impossible to secure a firm protective scab. The long duration of the exudation depends in part on the fact that the action of the poison continues for a considerable time after it has been absorbed by the skin, and the damage is therefore progressive. Measures which result in a reduction of the local oedema are therefore desirable.

Treatment at this stage with Amyl. Salicylate helps to dry up the exudation, reduces the surrounding oedema and erythema, and diminishes the pain, irritation and discomfort. A pad of gauze soaked in amyl salicylate, and wrung out, should be applied and covered with cellophane and a thin layer of cotton wool which should be lightly bandaged. The pad should be changed either once or twice a day.

When the exudation has subsided and the wound is dry, at the end of several days, if progress is unsatisfactory, amyl salicylate may be discontinued, and a dressing of crude cod liver oil (of neutral reaction) may be substituted after removing any loose fragments of blister skin.

Amyl salicylate must not be used for burns of the face since its vapour is irritant to the eyes. The only objection to amyl salicylate is it clinging, sweet smell.

In the absence of amyl salicylate, a pad of sterile gauze wrung out in sterile normal saline should be applied to the burn in the early stages, being changed as often as it becomes soaked with exudation. As soon as the exudation has diminished sufficiently, the blister skin should be removed and the area treated with triple dye solution, or gentian violet jelly, as in the case of a thermal burn. Triple dye or cod liver oil should in any case be used for burns on the face. Triple dye should be used for the treatment of burns associated with wounds, e.g. compound fractures. Tannic acid or one of its preparations, e.g., Tannafax, can be substituted for triple dye, but it is not so successful in forming a satisfactory and adherent coagulum. Tannic acid should not be used for burns of the face or hands.

The healing of mustard gas burns is a slow process. In the case of the deeper burns a granulating area may be left, and treatment with a stimulating ointment, e.g., scarlet red ointment, may be helpful, care being taken not to damage the new granulation tissue.

Severe burns in the neighbourhood of a joint may demand immobilization until healing is well advanced.

If the burn becomes septic, or there is deep necrosis of the skin, mildly antiseptic baths may be useful and soothing, warm hip baths of isotonic salt solution allaying the intense irritation of mustard gas burns of the genitalia. Starch poultices, hot compresses or fomentations may also prove of service - in fact any treatment suitable for other septic conditions of the skin. There is nothing to contraindicate the use of powdered sulphanilamide on the wound.

18. General treatment.

Where nausea, vomiting or epigastric discomfort is present, the diet should be light and fluids may be given freely, especially milk and beef-tea; should these not be retained, the administration of 10 to 20 grs. of sodium bicarbonate may be of assistance, and the patient should be encouraged to drink water freely. As convalescence proceeds, and in all cases of uncomplicated body burns, a full diet is required, and this should be as varied as possible. Cases showing evidence of commencing fever, which may be a prelude to broncho-pneumonia, should be suitably dieted.

Quoting from the "Official History of the War" :- "The management of the convalescent period provides the great test for the Medical Officer's ability, because he is required not only to treat the disease, but to restore morale, to cut short hospitalization, and to lift men out of the slough of self-analysis which so often follows gassing. The best results will therefore be obtained by placing gassed cases in selected hospitals under the care of Medical Officers with special aptitude for this.

"As soon as a man is convalescent and free from the danger of septic complications, he should be discharged from hospital to a convalescent centre, where a well ordered routine of exercise, employment, amusement and rest will quickly restore him to a state of physical and mental fitness."

19. Functional after-effects.

The Great War proved that this subject is one of importance and that functional disorders led to a degree of wastage and invalidism which, to some extent, could have been avoided if personnel generally, and Medical Officers in particular, had been more conversant with the limitations as well as the potentialities of chemical warfare substances.

Functional disorders fall in the main into two classes. In the first, exposure to gas, often to a minimal and barely a toxic concentration, may yet prove the final factor in upsetting a nervous system already breaking down as the result of physical or mental strain. In such circumstances, and especially when combined with ignorance, it may produce an "anxiety state" similar in all respects to the neurosis so common in the Great War.

The second class is a more important one, because in these cases a local, but real, organic lesion from mustard gas causes certain irritant reflexes, such as coughing or photophobia, and these sensory reflexes are perpetuated by introspection, almost in a form of conversion hysteria, long after their organic cause has been cured. Lack of appreciation of this possibility by Medical Officers will cause much delay in returning men to duty.

Functional photophobia and aphonia are responsible for the great majority of cases. This is not surprising when it is realized that the initial trauma affects a highly organized special sense, and that fear of blindness or dumbness resulting from the injury may very wen act to prolong the symptoms. Ill-advised and unnecessary treatment, however, is also a probable factor in many cases, as, for example, the continued retention of eye-shades long after the necessity for them has passed and the actual lesions have totally disappeared. There can be no doubt that the suggestive influence of wearing a shade under these conditions will prolong the functional manifestation.

Persistent aphonia, often accompanied by a useless, harsh cough. is another striking evidence of auto-suggestion arising from the initial irritation. The characteristic cough is either dry, or accompanied by watery sputum mainly of salivary origin. It is usually much worse at night, and is of a ringing harsh quality. If the Medical Officer realizes the nature of the condition and gives the patient confidence in his early recovery, this functional aphonia yields very rapidly to treatment by suggestion and breathing exercises.

Of all after-effects, functional or organic, those which seem to affect present the greatest. difficulty in assessment. Effort syndrome (formerly known as disordered action of the heart) with its shortness of breath and tachycardia following exercise, arises from so many diverse causes was that gassing, in the Great War, was naturally regarded as one of them.

It is clear, however, that under competent medical treatment, the incidence f effort syndrome-in mustard gas casualties should be very low when serious complications, such as broncho-pneumonia, have been absent.

20. Invalidism after mustard gas poisoning.

Experience from the Great War showed that the chemical damage to the skin, to the respiratory passages, and to the outside of the eyes cause prolonged devitalization of these tissues and a poor resistance to secondary bacterial infection, but no deeper trouble resulted. There has been no subsequent evidence of the irritation leading to later malignant changess in any tissue. The skin ultimately regained perfect vitality. (Editor's note: This statement is now known to be untrue, mustard gas has now been shown to be carcinogenic)

The trachea and bronchi in some cases showed a tendency to relapses of bronchitis but there was no special proneness to pulmonary tuberculosis.

In a few, and fortunately very rare, cases the cornea never regained its natural vitality, and after even 15 or 20 years a superficial abrasion and might spread rapidly and cause permanent loss of sight.

Invalidism in general was not prolonged, but it should be remembered that the casualties dealt with in the war were very largely from exposure to mustard gas vapour, and only rarely had they been effected by direct splashes of the liquid. In all cases admitted to hospitals there was some degree of conjunctivitis and laryngitis as well as skin burns. The skin lesions from vapour healed quickly, usually in less than a month. Prolongation of. invalidism was due rather to trouble in the respiratory passages and eyes, and to general debility. By following up the times of recovery m a large number of cases at convalescent depots in France, it was proved that at least 75 per cent. of mustard gas casualties admitted to hospitals in the lines of communication, these being the severer cases, evacuated from the army zone, could be returned to full duty in less than eight weeks. This involved an average stay in hospital of two to three weeks, during the last half of which time the casualties did not require to be in ward beds or to be specially attended by nursing orderlies.

The worst cases might remain in hospital for two months or even longer. Photophobia, either functional or associated with a tendency to recurrent keratitis, often lingered. Next as causes of invalidism came bronchitis and laryngitis, and lastly effort syndrome and neurasthenia or general debility. But out of a group of nearly 800 severe cases detained in hospital beyond the ninth week, none died and ultimately only 0.5 per cent. of these severe cases were discharged as permanently unfit for service. The ultimate invalidism from mustard gas vapour was therefore very small. As in phosgene poisoning, it is probable that any persistent chest trouble was due to mischief wrought by the smouldering inflammation of secondary bacterial infections rather than by a direct chemical action. Doctors should realize that gas poisoning, whatever the chemical irritant concerned, does not in itself cause a permanent poisoning of the patient or chronic impairment of his health. It is necessary to insist on this truth lest the patient be allowed to develop a morbid dread, and drift into neurasthenia and general debility.

21. Decontamination of clothing, equipment and materials.

A very essential measure of prophylaxis against injury from mustard gas is the systematic decontamination of all clothing, equipment, materials and other objects contaminated by the gas. Our knowledge of the stability of this vesicant, its penetrative power and its persistent character forces us to realize that all such clothing and materials will be dangerous to wear or to handle until they have been subjected to some process, active or passive, which will ensure either the destruction or the removal of the mustard gas they may contain.

Although the Medical Officer is responsible only for the personal decontamination of individual contaminated casualties (i.e. persons who are both contaminated and sick or injured) who come under his care, it is important that he be familiar with the general principles on which decontamination is based, as the degree of efficacy of a particular process in given circumstances may have a direct bearing on the incidence of mustard gas casualties.

Satisfactory decontamination is essentially a skilled process, hence the personnel employed in carrying it out must be trained for the purpose. Moreover, they must possess a knowledge of chemical warfare substances and their characteristics if they are to make effective use of any anti-gas measure they may adopt. These measures will vary, in the case of mustard gas, according to the material to be decontaminated, the nature and extent of the contamination, and the environment, the process adopted in a particular case being often dependent on local conditions and the facilities available.

Decontamination of stretchers. - If the ordinary pattern of stretcher is splashed with liquid mustard gas it is difficult to obtain complete decontamination, since the canvas is fixed to the woodwork by a large number of nails, which renders the removal and replacement of the canvas impracticable under field conditions. It is therefore important to adopt all possible measures to prevent contamination occurring.

Stretchers, when not actually being used, should, therefore, be kept under cover (e.g. indoors or under any improvised roof, tarpaulin, etc.) to prevent them being splashed with liquid blister gas. As an additional precaution the canvas should be covered with a stretcher cover. The standard article is made of special laminated paper and is expendable. This will prevent or delay the canvas of the stretcher being contaminated when carrying contaminated casualties. Alternatively, if a standard stretcher cover is not available the stretcher canvas may be protected with an improvised cover of a resistant material such as a ground sheet, anti-gas cape, etc. Such improvised covers can be decontaminated after use, if necessary, by one of the standard methods.

If, in spite of precautions, contamination does occur, the complete stretcher should be scrubbed with bleach paste and later washed thoroughly with water, after which it should be left to weather as long as possible. The handles may not be safe for contact with the bare hands but this difficulty can be overcome by wearing anti gas gloves. Any danger from residual contamination on the canvas can be counteracted by the use of the covers described above.

If the canvas can be readily removed it can be decontaminated by immersing it in boiling water for 30 minutes.

Stretchers which have been exposed to mustard gas vapour only should be allowed to weather in the open air.