Chapter XIV: Part III: Preventive Measures Against Industrial Poisoning (1)

I

_GENERAL MEASURES_

In discussing preventive measures against industrial poisoning the deductive method from the general to the particular will be followed. The numerous instances of poisoning mentioned in Part I afford a practical basis on which to formulate general rules before passing on to describe special measures. Technical details will be omitted, as they must be left to the technical expert whose business it is to draw up the plans as a whole and to modify them according to the requirements of individual cases.

In the effort to control industrial poisoning and disease it is necessary to insist absolutely on the concerted action of all concerned. In this co-operation every one is called who through his knowledge and sphere of activity is in a position to assist.

The medical man comes in with his special knowledge of the action of poisons as toxicologist, as practising physician (especially as works surgeon and doctor of the sick insurance society), and also in an official capacity as appointed surgeon or medical officer of health; the technical expert comes in as engineer, as manager, as foreman, and as factory inspector. But above all the interest and active co-operation of employers and employed are needed as well as the organisations of both. That the workers should understand and co-operate is essential for the success of preventive measures, and subsequently it will be shown in what direction this co-operation is most necessary.

To make possible such co-operation interest must be aroused and suitable information and teaching supplied to the parties concerned. Medical men and practical workers require to receive instruction in industrial hygiene, and teaching on this subject should be arranged for in secondary and technical schools. Medical men and others who, as officials and insurance doctors, are brought constantly into touch with industrial workers should have opportunity—by means of special courses and lectures—to keep pace with advancing knowledge in this direction. Beside these there are, as educative organisations, special Institutes of Industrial Hygiene and special hospitals for treatment of diseases of occupation which bring together the patients and the teaching staff and so facilitate pursuit of knowledge and research. A beginning of this kind has already been made by the Industrial Hygiene Institute, Frankfurt a.-Main, and the hospital for diseases of occupation at Milan, showing that the ideas are attainable. International agencies which unite all circles interested in the subject irrespective of profession or nationality in common interchange of thought and discussion are of great significance for uniform development of needful preventive measures; international congresses, often in connection with exhibitions, have given valuable stimulus and have been the starting-point of permanent international societies, unions, and organisations. The significance for our inquiry of these international efforts will be more closely considered in the following pages.

II

_GENERAL CONSIDERATIONS ON SOCIAL AND LEGISLATIVE MEASURES_

INTERNATIONAL PREVENTIVE MEASURES, NOTIFICATION OF INDUSTRIAL POISONING, LISTS AND SCHEDULES OF INDUSTRIAL POISONS

Experience and inquiry in the field of industrial poisoning led to a series of demands which, supported as they were by a general movement for the protection of workers, were soon followed by regulations and legislative action. For a long time efforts have been directed to treat industrial disease and poisoning in the same way as has been done in the case of industrial accidents. The question, however, is attended with much greater difficulty. On the other hand, uniform international regulation of questions affecting prevention of disease is called for both on humanitarian and economic grounds.

The idea of international legislation for the protection of workers was first mooted about the year 1870. The possibility and need of such intervention was much discussed and interest in it kept constantly alive, especially in Switzerland, until the organisations of the workers took up the idea. Several attempts failed. In France in 1883 a proposal of the Socialist party aiming at international agreement on the subject of protection of the workers was rejected. In 1885 (in opposition to Hertling) Prince Bismarck expressed himself strongly against the possibility of such international protection. But the stone, once set rolling, could not be stayed. In the years 1886, 1887, and 1888 the French and English trade unions, as well as the Swiss Federal Council, took up the question afresh. These endeavours at last took tangible shape in the first International Conference for the protection of workers held in Berlin in March 1890. This date remains a landmark in the history of the subject, but not until ten years later—1900—did the Congress held in Paris for the international legal protection of workers lead to the establishment of what had been repeatedly urged, namely, creation of an International Bureau. This was inaugurated at Basle in 1901 and forms the headquarters of the National Associations for Labour Legislation called into being in various countries.

This International Association meets regularly in conference, as in Cologne (1902), Berne (1905), Lucerne (1908), Lugano (1910), and Zurich (1912). The questions raised in the International Labour Bureau, which receives financial aid from a number of States, are fully and scientifically discussed with the object of finding a basis on which to bring into agreement the divergent laws of the different countries. A further task of this strictly scientific institution is the collection and publication of literature bearing on the protection of workers in one and another country, distribution of information, and the editing of reports and memoranda. The question of prevention of industrial poisoning has always taken a foremost place in the programme of the International Association and in the agenda of the International Labour Bureau. At its first meeting a resolution was adopted advocating the prohibition of the use of white phosphorus and white lead, and the Labour Bureau in Basle was instructed to take the necessary steps. Special, if not prohibitive, economical considerations foreshadowed difficulties—all the greater because the matter at issue concerned prohibition of articles playing a part in the markets of the world. Just on that account international treatment of such questions is necessary, since a peaceful and orderly solution can only be arrived at on such lines. International effort endeavours here to press with equal weight on the countries competing with one another commercially, so that in the protection of the workers economic adjustment is sought in order that efforts based on humanitarian grounds shall not at the same time cause economic disadvantages, the aim being to produce general welfare and not merely protection of one class at the expense of another.

Through these international agreements between various countries success in the direction aimed at is hopeful, and indeed to a certain extent—as in the phosphorus and lead questions—actually attained. Thus, for example, Germany and Italy were in a position to enforce prohibition of the use of white phosphorus early, while their neighbour Austria, on account of commercial and political considerations and the conditions of the home lucifer match industry, has only recently decided on prohibition.

As international agreement for the protection of workers is advisable on economic grounds, so also is it reasonable and just from purely humanitarian reasons that workers, without reference to civil condition or nationality, should be equally protected. On this point it is proposed to take a vote and to press only for those reforms which are thoroughly sound and recognised as necessary.

The first step in such a comprehensive attack is precise knowledge of the extent and source of origin of the particular forms of industrial poisoning and disease and the collection of reliable statistics. This suggested the obligation to notify such cases to the proper authorities in the same way as is now done in the case of infectious disease. A motion to this effect had already been passed at the Conference of the International Association for Labour Legislation held in Basle, and a request was made to the Labour Bureau to prepare a list of the diseases and poisonings in question. To them we shall refer later, but a schedule is necessary as a basis to work upon. Yet even when this is done there are obviously great difficulties to be overcome in carrying out the requirement of notification when the aim is kept in mind of collecting complete statistical data for controlling the conditions giving rise to industrial disease. The proposal of the International Association seeks to make notification obligatory on the part both of the medical practitioner in attendance and the occupier, and in connection with this to secure the co-operation of the Sick Insurance Society.[D] The proposal to require the appointed surgeons and surgeons of the Insurance Society to notify all cases is hardly feasible in view of their dependent position. Nor can the obligation on the occupiers lead to the desired result because of their lack of medical knowledge and the fact that by notifying they might be forced to act to their own disadvantage. A successful effort in this direction is recorded in Saxony, where lead poisoning was first made a notifiable disease, and later the general duty of notification of industrial poisoning was prescribed by Order dated March 4, 1901.

+-----------------------+-----------------------------------------------+
| | Reported Cases.[E] |
| Disease and Industry. +-------+-------+-------+-------+-------+-------+
| | 1912. | 1911. | 1910. | 1909. | 1908. | 1907. |
| (1) | (2) | (3) | (4) | (5) | (6) | (7) |
+-----------------------+-------+-------+-------+-------+-------+-------+
|Lead Poisoning |587 (44|669 (37|505 (38|553 (30|646 (32|578 (26|
| 1. Smelting of metals| 56 (7| 48 (3| 34 (5| 66 (5| 70 (2| 28 (2|
| 2. Brass works | 5 | 9 (1| 7 | 5 | 6 | 9 (1|
| 3. Sheet lead and | | | | | | |
| lead piping | 6 | 12 | 4 | 9 (2| 14 | 6 |
| 4. Plumbing and | | | | | | |
| soldering | 35 (5| 37 (2| 25 (1| 28 | 27 | 20 (2|
| 5. Printing | 37 | 32 (2| 33 (4| 21 (1| 30 (2| 26 (3|
| 6. File cutting | 13 | 18 (2| 9 (1| 8 | 9 (2| 10 |
| 7. Tinning | 15 (11| 13 | 17 | 22 | 10 | 25 |
| 8. White lead | 23 | 41 (2| 34 (1| 32 (2| 79 (3| 71 |
| 9. Red lead | 3 | 13 (1| 10 | 10 | 12 | 7 |
| 10. China and | | | | | | |
| earthenware | 80 (14| 92 (6| 77 (11| 58 (5|117 (12|103 (9|
|10a. Litho-transfers | 1 (1| 1 | 1 | 1 | 2 | 10 |
| 11. Glass cutting and | | | | | | |
| polishing | 1 (1| 5 | — | 4 (2| 3 (1| 4 |
| 12. Vitreous | | | | | | |
| Enamelling | 5 | 19 (1| 17 | 7 | 7 | 6 |
| 13. Electric | | | | | | |
| accumulators | 38 (1| 24 (1| 31 | 27 (2| 25 (1| 21 |
| 14. Paints and colours| 19 | 21 | 17 (1| 39 (2| 25 | 35 (1|
| 15. Coach building | 84 (7|104 (5| 70 (6| 95 (6| 70 (3| 70 (3|
| 16. Ship building | 34 (2| 36 (6| 21 (2| 27 (1| 15 | 22 (1|
| 17. Paint used in | | | | | | |
| other industries| 48 (3| 56 (1| 51 (3| 42 | 47 (1| 49 (2|
| 18. Other industries | 84 (2| 88 (4| 47 (3| 52 (2| 78 (5| 56 (2|
| | | | | | | |
|Phosphorus Poisoning | — | — | — | 3 | 1 | 1 (1|
| | | | | | | |
|Arsenic Poisoning | 5 | 10 (1| 7 | 4 | 23 (1| 9 (2|
| | | | | | | |
|Mercurial Poisoning | 17 | 12 | 10 (1| 9 | 10 | 7 |
| | | | | | | |
|Anthrax | 47 | 64 (11| 51 (9| 56 (12| 47 (7| 58 (11|
| Wool | 31 (6| 35 (10| 28 (3| 28 (3| 18 (3| 23 (3|
| Horsehair | 7 | 8 (1| 6 (1| 8 (2| 10 | 17 (4|
| Handling of hides and | | | | | | |
| skins | 8 | 20 | 14 (3| 18 (6| 13 (1| 12 (2|
| Other industries | 1 | 1 | 3 (2| 2 (1| 6 (3| 6 (2|
+-----------------------+-------+-------+-------+-------+-------+-------+

+--------------+-------+-------+-------+-------+-------+-------+--------+
| | 1906. | 1905. | 1904. | 1903. | 1902. | 1901. | 1900. |
| | (8) | (9) | (10) | (11) | (12) | (13) | (14) |
+--------------+-------+-------+-------+-------+-------+-------+--------+
|Lead |632 (33|592 (23|597 (26|614 (19|629 (14|863 (34|1058 (38|
| 1. | 38 (1| 24 (1| 33 (1| 37 (2| 28 | 54 (3| 34 (1|
| 2. | 11 | 5 (1| 10 (1| 15 | 5 | 6 (1| 3 |
| 3. | 7 | 9 | 7 | 11 | 12 | 17 | 17 (1|
| 4. | 16 (4| 24 (2| 21 (3| 26 | 23 (1| 23 | 9 |
| 5. | 16 (2| 19 (4| 15 | 13 (2| 19 | 23 (1| 18 (2|
| 6. | 15 | 12 | 20 (4| 24 (2| 27 (1| 46 (7| 40 (3|
| 7. | 18 (1| 14 (1| 10 | 14 | 11 | 10 | 5 |
| 8. |108 (7| 90 |116 (2|109 (2|143 (1|189 (7| 358 (6|
| 9. | 6 | 10 | 11 | 6 | 13 | 14 | 19 |
| 10. |107 (4| 84 (3|106 (4| 97 (3| 87 (4|106 (5| 200 (3|
| 10a. | 5 | 5 | 3 | 3 | 2 | 7 | 10 |
| 11. | 4 (1| 3 | — | 4 | 8 (2| 11 (3| 7 |
| 12. | 4 | 2 | 3 | 4 | 3 (1| 9 | 11 |
| 13. | 26 | 27 (1| 33 | 28 | 16 (1| 49 (1| 33 |
| 14. | 37 | 57 (1| 32 (1| 39 (1| 46 | 56 | 56 (1|
| 15. | 85 (7| 56 (3| 49 (4| 74 (5| 63 (1| 65 (4| 70 (5|
| 16. | 26 (1| 32 (2| 48 | 24 (1| 15 (1| 28 (1| 32 (2|
| 17. | 37 (3| 49 (2| 27 (3| 46 (1| 44 (1| 61 | 50 (5|
| 18. | 66 (2| 70 (1| 53 (3| 40 | 64 | 89 (1| 86 (4|
| | | | | | | | |
|Phosphorus | — | 3 (1| 1 (1| — | 1 (2| 4 | 3 |
| | | | | | | | |
|Arsenic | 5 | 1 | 5 | 5 | 5 | 12 (1| 22 (3|
| | | | | | | | |
|Mercurial | 4 | 8 | 3 | 8 | 8 | 18 | 9 |
| | | | | | | | |
|Anthrax | 67 (22| 59 (18| 50 (10| 47 (12| 38 (9| 39 (10| 37 (7|
| Wool | 24 (8| 34 (12| 12 (1| 20 (5| 12 (2| 6 (4| 9 (2|
| Horsehair | 10 (4| 7 (1| 12 (4| 7 (1| 10 (2| 9 (1| 12 (3|
| Hides | 19 (7| 17 (4| 18 (3| 12 (1| 11 (5| 20 (5| 9 (1|
| Other | 14 (3| 1 (1| 8 (2| 8 (5| 5 | 4 | 7 (1|
+--------------+-------+-------+-------+-------+-------+-------+--------+

My own experience does not lead me to expect much in elucidation of industrial diseases from the Sick Insurance Societies. In Austria they make a statistical return as to the causation of illness to the central authorities. I have myself—in my capacity as an official of the State Central Board—examined these in order to try and gain knowledge of the extent of industrial disease in Bohemia. In spite of the returns drawn up by the district surgeon who visits the factories in question, it was impossible for me to obtain a complete picture of the extent of industrial sickness. The reports only give valuable data on which to base action in particular cases, and from this standpoint I do not under-estimate their value. But so far as the expressed wish of the International Association is concerned they appear to fulfil it, inasmuch as for specially dangerous trades special reports are issued, the Austrian law for sick insurance requiring such industries to institute separate sick insurance funds with separate statistics. Hence, under present conditions, I do not see how the duty of notification will be effective. There remains the endeavour to secure insurance and the right to claim compensation for industrial disease in the same way as is provided for accidents. This point was fully discussed at the eighth International Congress for Workmen’s Insurance held in Rome in 1908. There is no valid ground for granting compensation only for _sudden_ disturbance of health arising in the course of employment by accident or acute poisoning, and withholding it in the case of _gradual_ disturbance of health caused equally by the trade, as the effects of such chronic indisposition weigh often no less heavily on the sufferer. Inclusion of industrial disease in the same category as accident insurance, as indeed has been done in France, Switzerland and Great Britain, has, apart from the fact that it is dictated by fairness and humanity, the advantage of removing existing hardship and of solving doubtful cases. Correct statistics, further, would thus be obtainable for the first time, and the employer by insurance would be freed from the legal proceedings now frequently brought against him for injury due to chronic industrial poisoning. And it seems the more right and just course to institute a general scheme of insurance against industrial disease than to have recourse to an Employer’s Liability Act in this or that case, particularly as the question often arises in regard to a disease which develops gradually—In whose employment was the disease contracted?

Clearly in such a scheme of insurance against both accident and industrial disease only specific industrial diseases would be included, i.e. diseases in which the connection with the industry can be clearly established as due to causes inherent in the industry, and traceable to definite materials used. Such diseases as tuberculosis and the effects of dust inhalation (bronchitis, &c.), which as industrial diseases occur only too often, cannot be called specific, because they arise outside the industry and make decision impossible as to whether or not in a particular case the disease owed its origin to the occupation. In order to determine what should be regarded as specific industrial poisons it was deemed necessary to draw up a schedule. For one such list Sommerfeld (in collaboration with Oliver and Putzeys) is responsible, Carozzi of Milan for a second, and Fischer[F] for a third, published in 1910. Those by Sommerfeld and Fischer are constructed in similar fashion—enumeration of (1) the poisonous substance, (2) the industries in which it is made or used, (3) the channel of absorption, and (4) the symptoms produced. Sommerfeld enumerates the poisons in alphabetical order, noting against each the requisite preventive measures, while Fischer adopts a chemical classification, confining himself to general introductory remarks as to prevention.

Sommerfeld proposes to limit notification to poisoning sharply defined as to the symptoms set up, such as lead, phosphorus, mercury, arsenic, chromium, carbonic oxide, aniline, benzene, nitrobenzene, carbon bisulphide, and nitrous fumes. This simplifies the obligation to notify, but does not dissipate the fears expressed above as to the difficulty, because in the present development of the chemical industries new substances involving new danger to the persons handling them are constantly being discovered, and thus there can be no finality as to which industrial poisonings should entitle to compensation. And if recourse were had from time to time to additions of new substances to the schedule, reliance would have to be placed on experience with regard to each substance added, and thus the actual individual who had suffered would not benefit. Fischer, indeed, acknowledges that any schedule must be incomplete, and emphasises the fact that continual additions would be necessary; otherwise it would be better to refrain altogether from publication of a list. Such lists may be valuable guides, but no sure foundation for insurance legislation. The only possible way to do this is to give as far as possible a correct definition of the industrial diseases entitling to compensation and, in isolated cases, to leave the decision to the expert opinion of competent judges.

Extension of workmen’s insurance to cover chronic industrial poisoning is, however, most desirable in the interest of employers and employed, and also of science. The German accident insurance legislation is especially suited to do this, since the trade organisations direct their attention not only to the prevention of accidents but of industrial diseases also.

III

_SPECIAL PREVENTIVE MEASURES FOR WORKERS_

SELECTION, CHOICE OF TRADE, ALTERNATION OF EMPLOYMENT, MEDICAL CONTROL, SAFETY APPLIANCES, INSTRUCTION AND CO-OPERATION OF WORKERS, CLOTHING, ATTENTION TO CLEANLINESS, FOOD, GENERAL WELFARE

As a practical measure in protection against trade risk selection of those capable of resisting danger has to be considered. It is obviously desirable to select for employment in a dangerous trade persons possessing powers of resistance, because predisposition and resistance to the action of poisons differ markedly in individuals. To some extent such a selection comes of itself, as those who are very susceptible are obliged by repeated attacks to give up the work. The social and physical misery, undeserved loss of employment, illness, and perhaps early death following on this kind of selection might be checked by timely medical examination so as to weed out the unfit. But medical examination prior to admission into a dangerous trade (actually practised in many industries involving risk of poisoning) inflicts hardship on those seeking employment, and recruits the ranks of the unwillingly unemployed. It would be much better were it possible to meet the need of selection by pertinent direction and guidance in choice of calling. There should be insistence in technical schools especially on the dangers inherent in certain industries, school medical examination as to physical qualifications for certain industries, and careful note made of individual suitability in labour bureaus, apprentice agencies, and the like.

Young female workers, naturally less able to resist, should be excluded from work involving risk of poisoning—a principle which has been acted on in the legislation of civilised countries.

Further, workers engaged in industries involving risk should not be exposed to the pernicious influence for too long a time. Hence the hours of employment should be shortened in occupations proved to be injurious to health. An important aid in this respect is alternation of employment. Change of occupation is particularly recommended where the nature of the poisoning of which there is risk is cumulative in action, because in the intervals from the work the system will rid itself of the accumulated store. In this way a number of skilled resistant workers, familiar with the risk and knowing how to meet it, will be maintained. Casual labour works in a vicious circle—increase of fresh workers increases the danger and the number of cases of poisoning, and, _vice versa_, these augment again the need of change in the personnel, so that the number of cases of poisoning rises very high. Thus the industry itself may be endangered, since its prosperity depends mainly upon the existence of a skilled staff of workers. In dangerous trades, therefore, Hermann Weber’s words, ‘Change of work instead of change of workers,’ have much force.

Periodical medical examination in these industries cannot well be omitted in order to weed out the physically unfit, and to suspend from work those who show early symptoms. Note should be kept of the state of health of the workers, the results of the periodical medical examination, the duration of symptoms, and the treatment of any illness that occurs. Medical supervision presupposes special training and experience in the medical man entrusted with the task.

Further, in some industries in which poisonous materials are used, especially such as set up acute sudden poisoning, there should be a trained staff competent to recognise the first symptoms of poisoning and to render first aid, and having at its disposal adequate means of rescue.

Apart from the rescue appliances generally needed in dangerous trades, stress must be laid on the value of oxygen apparatus as a means of saving life. In addition to what is needed for the sufferer there must be defensive apparatus at hand for the rescuers (breathing helmets, &c.), to facilitate and make safe their rescue work when in a poisonous atmosphere. Without such defensive equipment rescuers should never venture into gas conduits, or into any place where presumably a poisonous atmosphere is to be met with. It hardly requires to be said that in dangerous industries medical aid should be within easy reach; in large works actual medical attendance may be necessary.

In acute as well as in chronic cases of poisoning early medical intervention is advisable. Hence medical aid should be sought on the earliest appearance of symptoms, and the worker, therefore, should know the nature and action of the poison with which he comes into contact. This brings us to the subject of the education of the worker and particularly observance of all those rules and regulations in which his co-operation is necessary. This co-operation of the workers is indispensable; it is the most important condition of effective defence. The best regulations and preventive measures are worthless if the worker does not observe them. He must be taught their aim, the way of using the means of defence; he must be admonished to use them, and, if necessary, compelled to do so. The co-operation of workmen’s organisations in this matter can avail much, since a workman most readily follows the advice of a fellow-worker.

Teaching of the kind suggested can be done in different ways. Apart from lectures and practical courses, concise instructions, either in the form of notices or as illustrated placards, should be posted up in the workrooms or handed in the form of leaflets particularly to the newly employed. Distribution of such leaflets might well be placed as a duty on the employer.

Of preventive measures applying to the individual those are of prime importance which serve to protect the worker, as far as is practicable, from coming into contact with the poison. Protection of this kind is attained by wearing suitable clothing, use of respirators, and careful cleanliness—especially before partaking of food. It cannot be too strongly urged that these precautions are a very potent defence against the danger of industrial poisoning, especially of the chronic forms, and in teaching workers their importance must be insisted on. It is not sufficient merely to put on overalls over the ordinary clothes. The ordinary clothes must be taken off before the commencement of work, and working suits put on, to be taken off again before the principal midday meal and before leaving work. They should be made of smooth, durable, washable material, and be properly washed and dried not less often than once a week. They must be plainly cut without folds or pockets.

Direct handling of the poisonous substances is to be avoided, but where this is necessary impervious gloves may have to be worn, especially in the case of poisons which can be absorbed through, or act injuriously on, the skin. If there is risk of splashing or spilling of poisonous liquids on to the clothes, impermeable or partly impermeable overalls (aprons, &c.) should be worn. The obligation of providing the overalls or working suits falls naturally on the employer in industries where poisonous substances are used, and there is equally obligation on the employee to use the articles provided.

Suitable cloakroom accommodation is essential, by which is meant room not only to change clothes with cupboards or hooks on one side for clothing taken off on commencement of work and on the other the working suits, but also ample washing accommodation. These cupboards should be double, that is, be divided by a partition into two parts, one serving for the ordinary and the other for the working clothes.

Protection of the respiratory organs can to some extent be obtained by so-called respirators worn over the mouth and nose. Often they consist simply of a moist sponge or folds of cloth, or again may be complicated air-proof affairs enclosing mouth and nose, or the whole face like a mask, or even the head like a helmet; they fit close, and the aperture for respired air is provided with filtering material (cotton wool, &c.) placed between two layers of wire gauze. The outer layer of the gauze moves on a hinge, so that the filtering material can be renewed after each time that it has been used. The construction of respirators is extraordinarily varied. One form is illustrated. They must be light, and in order not to obstruct breathing seriously they are often provided with valves—closing during inspiration and opening during exhalation. Generally the respirators in common use do not quite satisfactorily fulfil the conditions required. After a time the pressure becomes irksome, the face becomes hot, breathing more difficult, and discomfort from wearing them unbearable.

Respirators are only to be regarded in the light of secondary aids and for occasional use.

During temporary exposure to an atmosphere charged with poisonous dust the wearing of an efficient apparatus—preferably one protecting the head—is very desirable.

Respirators afford no protection, or a very imperfect one, against dangerous gases or fumes. If soaked with an absorbing or neutralising fluid they can scarcely be worn for any length of time.

In an atmosphere charged with poisonous gas recourse should be had either to a smoke helmet with flexible tubing and bellows or to an oxygen breathing apparatus so constructed that the workman carries the necessary supply of oxygen with him in a knapsack on his back. In the latter case oxygen from a compressed cylinder of the gas is conveyed to the breathing mask, so that respiration is independent of the surrounding atmosphere.

P Alkali cartridges; K Cooler; C Aspirating pipe; L₁ Purified air; L₂ Expired air.]

The mode of working is represented diagrammatically in figs. 37 and 40. After putting on the helmet, the bag is first filled with fresh air, the air valve is then closed, and the valve of the oxygen cylinder unscrewed so as to permit of the flow of the oxygen which, mixes with the air in the bag, and begins to circulate; the expired air passes through the caustic potash pellets P, which free it of carbonic acid gas, so that, with a fresh supply of oxygen from the cylinder through the pipe C, it is regenerated and made fit for breathing again. The pressure in the cylinder is measured by a manometer, which indicates also when the supply of oxygen gives out.

Another apparatus—the ‘Proto’ patent self-contained breathing
apparatus (Fleuss-Davis patents)—is also illustrated in fig.
39. Illustration 40 gives a diagrammatic view of the principle
upon which it is designed. The instructions for using the
‘Proto’ apparatus are as follows:

_The oxygen cylinders_ (B, B), having been charged with oxygen
through the nipple at (H) to a pressure of 120 atmospheres
(about 1800 lbs. per square inch), are to be re-attached to
the belt as shown, and the reducing valve, with its tubes,
&c., is to be connected to the nipple at (H). This supply is
sufficient for fully two hours.

_Charging the breathing bag._—Put 4 lbs. of stick caustic
_soda_ into the bag (D), i.e. 2 lbs. into each compartment,
and immediately fasten the mouth of the bag by means of the
clamps and wing nuts (O). If the apparatus is not to be used
at once, but is to be hung up for use at some future time, the
indiarubber plug which is supplied with the apparatus should be
tightly fitted into the mouthpiece in order to prevent access
of air to the caustic soda, and to preserve it until required
for use.

See that the inlet and outlet valves (T and S) and the
connection (N) are screwed up tightly.

The small relief valve (K) is only to be opened (by pressing
it with the finger) when the bag becomes unduly inflated
through excess of oxygen. This may occur from time to time,
as the reducing valve is set to deliver more than the wearer
actually requires.

_Equipment._—The whole apparatus is supported upon a broad belt
which is strapped round the body. The bag is also hung by a
pair of shoulder braces.

The wearer having put the equipment over his shoulders, fastens
the belt and takes the plug out of the mouthpiece. The moment
the mouthpiece is put into the mouth or the mask is adjusted,
the main valve (H) is to be opened not more than one turn and
the necessary supply of oxygen will then flow into the bag. It
is advisable to open the by-pass (I) to inflate partially the
breathing bag (D) for a start, but this valve should again be
screwed up quite tight and not touched again, except in the
case of emergency as previously described should the bag become
deflated. Breathing will then go on comfortably.

Should the by-pass (I) on the reducing valve (C) get out of
order then the wearer should turn on the by-pass (I) from time
to time to give himself the necessary quantity of oxygen, but,
as stated above, this is only to be done in case of deflation
of the bag. The best guide as to the quantity of oxygen to
admit _in the above circumstances_ is the degree of inflation
of the breathing bag. It will be found to be quite satisfactory
if the bag be kept moderately distended.

_After using the apparatus._—The caustic soda should _at once_
be thrown away, but if it is neglected and the soda becomes
caked, it must be dissolved out with warm water before putting
in a fresh supply. Caustic soda will not damage vulcanised
indiarubber, but it will damage canvas and leather, and will
burn the skin if allowed to remain upon it.

If the apparatus is to be used again at once, it can be
recharged with caustic soda at once, but if it is only to be
charged ready for use at some future time the indiarubber bag
should be thoroughly washed out with warm water and dried
inside with a cloth or towel.

When emptying or recharging the rubber bag with caustic soda,
it must always be removed from the canvas bag. After use each
day, it is advisable to wash the rubber mouthpiece (or mask,
as the case may be) with yellow soap and water. This acts as a
preservative to the indiarubber.

Every man who is to use the apparatus should have his own
mouthpiece and noseclip, or mask, as the case may be, under
his own special care, both for sanitary reasons and so that he
may shape and adjust the mask to fit himself comfortably and
air-tightly, to such an extent that if the outlets are stopped
up by the hands while the mask is held in position by its bands
no breath can pass in or out.

Where poisonous substances giving off dust or fumes are used, regular washing and rinsing the mouth (especially before meals and on leaving) is of great importance. Naturally the washing conveniences (basins, soap, brushes, towels) must be sufficient and suitable, and the workers instructed as to the importance of cleanliness by the foreman. They should be urged to bath in rotation, and time for it should be allowed during working hours.

The taking of meals and use of tobacco in the workrooms must be prohibited. Meal rooms should be so arranged as to be contiguous to the cloakroom and washing accommodation, the worker gaining access to the meal room through the cloakroom and bathroom. The arrangement described is illustrated in fig. 41. The meal room serves also the purpose of a sitting-room during intervals of work, and it goes without saying that cloakroom and lavatory accommodation are as necessary in small as in large premises.

Simple lavatory basins of smooth impervious surface fitted with a waste pipe and plug, or tipping basins, are recommended in preference to troughs which can be used by several persons at once. Troughs, however, without a plug, and with jets of warm water, are free from objection.

The douche bath has many advantages for workmen over the slipper bath. The initial cost is comparatively small, so that it can be placed at the disposal of the workers at very small outlay. Maintenance and cleanliness of douche baths are more easily secured than of other kinds, where changing the water and keeping the bath in good order involve time and expense. A dressing-room should form part of the douche or slipper bath equipment. Walls and floors must be impervious and, preferably, lined with smooth tiles or cement. It is better that the shower bath should be under the control of the worker by a chain rather than be set in motion by means of mechanism when trodden upon. The arrangement of baths is illustrated in fig. 43. In many large works large bath buildings have been erected. Fig. 44 is a plan of the splendid bath arrangements at the colour works of Messrs. Lucius, Meister & Brüning of Höchst a.-M.

Naturally maintenance of the general health by good nourishing diet is one of the best means of defence against onset of chronic industrial poisoning. Over and over again it has been noticed that ill-fed workers speedily succumb to doses of poison which well-nourished workers can resist. It is not our province here to discuss fully the diet of a working-class population. We merely state that it is a matter of vital importance to those employed in dangerous trades. The question of a suitable drink for workers to take the place of alcohol calls for special attention, as, when complicated with alcoholism, both acute and chronic poisonings entail more serious results than they otherwise would do. Over-indulgence in alcohol, owing to its effect on the kidneys, liver, digestion, nervous system, and power of assimilation generally, requires to be checked in every way possible. Apart from good drinking water, milk, coffee, tea, fruit juices and the like, are excellent. Milk is especially recommended, and should be supplied gratis to workers in dangerous trades, notably where there is risk of lead poisoning.

Lastly, other features such as games and exercise in the open air, which help to strengthen bodily health, must not be forgotten. In this connection much good work has already been done by employers’ and workers’ organisations.

IV

_GENERAL REMARKS ON PREVENTIVE MEASURES_

GENERAL PRINCIPLES, SUBSTITUTES FOR DANGEROUS MATERIALS, CLEANLINESS OF WORKROOMS, CUBIC SPACE, VENTILATION, REMOVAL OF DUST AND FUMES

Preventive measures against industrial poisoning aim at an unattainable goal of so arranging industrial processes that employment of poisonous substances would be wholly avoided. Such an ideal must be aimed at wherever practicable. Prohibition of direct handling of poisonous substances is also sometimes demanded, which presupposes (although it is not always the case) that this is unnecessary or can be made unnecessary by suitable mechanical appliances. We have to be contented, therefore, for the most part, with removal of injurious dust and fumes as quickly as possible at the point where they are produced, and regulations for the protection of workers from industrial poisoning deal mainly with the question of the prevention of air contamination and removal of contaminated air. Substitution of non-injurious for injurious processes is only possible in so far as use of the harmless process gives technically as good results as the other. If such a substitute can be found let it be striven for. Mention has already been made of international prohibition of certain substances, and attention has been drawn to economical considerations affecting this point.

Prohibition obviously may paralyse branches of industry and hit heavily both employers and employed. The skilled trained workers are just the ones to suffer, since they are no longer in a position to take up another equally remunerative trade.

Judgment has to be exercised before enforcing new regulations in order that good and not harm may follow. If a satisfactory substitute be discovered for methods of work injurious to health, then ways and means will be found to make the alteration in the process economically possible. It may, however, demand sacrifice on the part of employers and employed, but the progress is worth the sacrifice.

The following are instances of substitution of safe processes for those involving risk: generation of dust can sometimes be avoided by a ‘wet’ method (watering of white lead chambers, grinding pulp lead with oil, damping of smelting mixtures, &c.); the nitrate of silver and ammonia process has replaced the tin and mercury amalgam used in silvering of mirrors; electroplating instead of water gilding (coating objects with mercury amalgam and subsequently volatilising the mercury); enamelling with leadless instead of lead enamels; use of air instead of mercury pumps in producing the vacuum in incandescent electric lamps.

Dealing further with the sanitation of the factory and workshop after personal cleanliness, the next most important measure is cleanliness of the workroom and purity of the air. Workrooms should be light and lofty; and have floors constructed of smooth impervious material easily kept clean. The walls should be lime-washed or painted with a white oil paint. Angles and corners which can harbour dirt should be rounded. Cleansing requires to be done as carefully and as often as possible, preferably by washing down or by a vacuum cleaner. Saturation of the floor with dust oil is recommended by some authorities in trades where poisonous dust is developed and is permitted as an alternative to the methods described. I refrain from expressing an opinion on this method of laying dust, since by adoption of the practice insistence on the need for removal of the poisonous material from the workrooms loses its force—a thing, in my opinion, to be deprecated.

The necessity of keeping the atmosphere of workrooms pure and fresh makes it essential that there should be sufficient cubic space per person and that proper circulation of the air should be maintained. The minimum amount of cubic space legally fixed in many countries—10-15 cubic metres—is a minimum and should be greatly exceeded where possible. Natural ventilation which is dependent upon windows, porosity of building materials, cracks in the floors, &c., fails when, as is desirable for purposes of cleanliness, walls and floors are made of smooth impermeable material, and natural ventilation will rarely supply the requisite cubic feet of fresh air quickly enough. Ordinarily, under conditions of natural ventilation, the air in a workroom is renewed in from one to two hours. Artificial ventilation therefore becomes imperative. Natural ventilation by opening windows and doors can only be practised in intervals of work and as a rule only in small workrooms. During work time the draught and reduction of temperature so caused produce discomfort.

_Artificial ventilation_ is effected by special openings and ducts placed at some suitable spot in the room to be ventilated and arranged so that either fresh air is introduced or air extracted from the room. The first method is called propulsion, the latter exhaust ventilation. Various agencies will produce a draught in the ventilating ducts, namely, difference of temperature between the outside and inside air, which can be artificially strengthened (_a_) by utilising the action of the wind, (_b_) by heating the air in the exhaust duct, (_c_) by heating apparatus, and (_d_) by mechanical power (use of fans).

Where advantage is taken of the action of the wind the exit to the ventilating duct must be fitted with a cowl.

The draught in pipes is materially increased if they are led into furnace flues or chimneys; in certain cases there is advantage in constructing perpendicular ventilating shafts in the building extending above the roof and fitted with cowls. Combination of heating and ventilation is very effective.

In workrooms, however, where there is danger of poisoning by far the most effective method of ventilation is by means of fans driven by mechanical power. All the means for securing artificial ventilation hitherto mentioned depend on a number of factors (wind, difference of temperature, &c.), the influence of which is not always in the direction desired. Exact regulation, however, is possible by fans, and the quantity of air introduced or extracted can be accurately calculated beforehand in planning the ventilation. In drawing up such a plan, detailing the arrangement, proportions of the main and branch ducts, expenditure of power, &c., a ventilating engineer should be consulted, as it is his business to deal with complicated problems of ventilation depending entirely for success on the design of the ventilation.

Injectors are usually only employed for special technical or economical reasons. A jet of steam or compressed air which acts on the injector creates a partial vacuum and so produces a powerful exhaust behind. Fig. 45 shows the mechanism of an injector. They are used for exhausting acid fumes which would corrode metal fans and pipes, and for explosive dust mixtures where fans are inadmissible.

In the industries described in this book fans are most commonly used. These are, in the main, wheels with two or more wing-shaped flattened blades. Some are encased, others are open and fitted by means of annular frames in the ducts according to the intended effect and kind of fan. Fans are of two kinds, propeller and centrifugal, and, according to the pressure they exert, of low, medium, or high pressure. They are now often driven electrically, in which case there is advantage in coupling them directly with the motor.

_Propeller fans_ have curved screw-shaped blades and are set at right angles in the duct upon the column of air in which they act by suction. The air is moved in the direction of the axis of the fan, and generally it is possible, by reversing the action, to force air in instead of extracting it. The draught produced is a low-pressure one (generally less than 15 mm. of water). The current of air set in motion travels at a relatively slow speed, yet such fans are capable, when suitably proportioned, of moving large volumes of air. Propeller fans are specially suitable for the general ventilation of rooms when the necessary change of air is not being effected by natural means.

_Centrifugal_ or _high-pressure fans_ (see figs. 48A and 48B) are always encased in such a way that the exhaust ducts enter on one or both sides of the axis. The air thus drawn in is thrown by the quickly rotating numerous straight blades to the periphery and escapes at the outlet. The centrifugal fan travels at a great speed, and the air current has therefore great velocity and high pressure. When the pressure is less than 120 mm. it is described as a medium, and when greater, a high-pressure fan. For the former a galvanised iron casing suffices; for the latter the casing requires to be of cast iron. Medium pressure centrifugal fans are used to exhaust dust or fumes locally from the point at which they are produced. They play a great part in industrial hygiene.

High-pressure fans are used mainly for technical purposes, as, for example, the driving of air or gas at high pressure. Localised ventilation is needed to limit diffusion of dust and fumes, which is attained in a measure also by separation of those workrooms in which persons come into contact with poisonous materials from others. Separation of workrooms, however, is not enough, as it is the individual who manipulates the poison for whom protection is desired. To enclose or hood over a dusty machine or fume-producing apparatus completely, or to close hermetically a whole series of operations by complicated technical arrangements, is only possible when no opening or hand feeding is required. Dangerous substances can only be wholly shut in by substitution of machinery for handwork.

FIG. 50B.

Ball Mills]

Where, however, absolute contact is unavoidable the dust or fume must be carried away at its source. This is done by exhaust ventilation, locally applied, in the following manner: A suitable hood or air guide of metal or wood is arranged over the point where the dust is produced, leaving as small an opening as possible for necessary manipulations. The hood is connected with a duct through which the current of air travels. An exhaust current dependent upon heat will only suffice in the case of slight development of dust or fumes. As a rule exhaust by a fan is necessary. Where exhaust ventilation has to be arranged at several points all these are connected up by branch ducts with the main duct and centrifugal fan. Where the ducts lie near the floor it is advisable to fix adjustable openings in them close to the floor to remove the sweepings.

_A_ Worm; _B_ Collector; _D_ Fan; _E_ Filter bag; _J_, _F_ Movable shutters; _H_ Jolting arrangement]

It is important for the exhaust system of ventilation to be designed in general so that the dust is drawn away from the face of the worker downwards and backwards. Many horrible arrangements are found in which the dust is first aspirated past the mouth and nose before it is drawn into a hood overhead. The proportions of the branch pipes to the main duct require to be thought out, and friction and resistance to the flow must be reduced as far as possible by avoidance of sharp bends. Branch pipes should enter the main duct at an angle of thirty degrees. A completely satisfactory system requires very special knowledge and often much ingenuity when the apparatus is complicated.

Disintegrators and edge runners can generally be covered in and the cover connected with an exhaust. Ball mills, when possible, are best as the rotating iron cylinder containing the steel balls and the material to be pulverised is hermetically closed.

Powdered material can be carried mechanically from one place to another by worms, screws, endless bands, or be driven in closed pipes by means of compressed air. The inevitable production of dust in packing can be avoided by the use of ventilated packing machines, which are especially necessary in the case of white lead, bichromates, basic slag, &c.

The difficulty is great in preventing dust in sieving and mixing, since this is mainly done by hand. Still here, for example, by use of cases with arm-holes and upper glass cover, injury to health can be minimised. Benches with a wire screen and duct through which a downward exhaust passes are useful in sorting operations (fig. 52).

Fig. 53 illustrates a grinding or polishing wheel fitted with localised exhaust.

To prevent escape of injurious gases all stills and furnaces must be kept as airtight as possible and preferably under a slight negative pressure. Agitators must be enclosed and should be fitted with arrangements for carrying on the work mechanically or by means of compressed air and, if necessary, exhaust ventilation applied to them. The aim should be to enclose entirely drying and extracting apparatus.

An important question remains as to what shall be done with the dust and fumes extracted. In many cases they cannot be allowed to escape into the atmosphere outside, and in the interests of economy recovery and utilisation of the waste is the thing to aim at. This vital subject can only receive barest mention here. The dust or fumes extracted require to be subjected to processes of purification with a view to recovery of the often valuable solid or gaseous constituents and destruction of those without value.

Dust-filter of Beth-Lübeck (_after Albrecht_)]

Collection of dust may take place in settling chambers as in a cyclone separator in which the air to be purified is made to travel round the interior of a cone-shaped metal receptacle, depositing the dust in its passage (see fig. 54).

_A_ Entry of dust laden air; _B_ Fan; _C_ Purified air; _D_ Pipe carrying away water and last traces of dust; _E_ Worm carrying away collection of dust.]

The most effective method, however, is filtration of the air through bags of canvas or other suitable fabric as in the ‘Beth’ filter (see figs. 55 and 56). In the ‘Beth’ filter a mechanical knocking apparatus shakes the dust from the bag to the bottom of the casing, where a worm automatically carries it to the collecting receptacle. In the absence of mechanical knocking the filtering material becomes clogged and increases the resistance in the system. Contrivances of the kind unintelligently constructed become a source of danger to the workers. Dust of no value is usually precipitated by being made to pass through a tower down which a fine spray of water falls. If the gases and fumes can be utilised they are either absorbed or condensed—a procedure of the utmost importance for the protection of the workers.

Condensation of the gases into a liquid is effected by cooling and is an essential part of all processes associated with distillation. The necessary cooling is effected either by causing the vapours to circulate through coils of pipes surrounded by cold water or by an increase in the condensing surface (extension of walls, &c.), and artificial cooling of the walls by running water.