Part 33

The methods of calculation can be best illustrated by one or two examples. What should be the number and size of flues and registers for fresh-air supply for a hospital ward to contain 24 beds, the ward being a rectangular pavilion with windows on opposite sides? In this case the room is constantly occupied, and the supply of air should be 1 cubic foot per head per second, or, in all, 24 cubic feet per second. The velocity of current at the registers should not exceed 3 feet per second--better only 2. This will require from 8 to 12 square feet of clear opening in the registers. If we allow four on each side of the room, each register must have at least 1 square foot of clear opening. The velocity of the air in the flues supplying these registers should not exceed 4 feet per second, and therefore the area of each flue should be about 9 by 12 {180} inches. Suppose the same question be asked with regard to a school-room to contain 48 pupils. In this case the room will not be occupied more than two hours at a time. The air-supply desirable may be put down at 35 cubic feet per head per minute, or 28 cubic feet per second for the whole. The velocity in the flues may be put, as before, at 4 feet per second; hence we need 7 square feet area of flue, or seven flues, each having 1 square foot of area. It is safe to say that there are not twenty school-houses in the United States which have fresh-air flues of sufficient area; the deficiency is made up, for the most part, by leakage of the outer air through cracks around windows and directly through the wall, and also by the passage of air from the central hall into the room, this last air coming from the cellar or basement.

The velocity of the air at the foul-air registers and in the foul-air ducts may be greater than in the fresh-air flues, since there is no danger of its causing draughts, and hence there is no truth in the common notion that the outlets should be larger than the inlets to allow for the expansion of heated air. It is important that the velocity of the current in the outlet shaft or chimney should be at least 8 feet per second at the point where it escapes into the outer air; and if the outlets be too large for the inlets, the result may be that some of the foul-air flues will work backward and become inlets. The plan of making everything a little larger than is necessary is not a safe one as regards chimney-flues and outlet shafts.

The merits of a plan of ventilation depend not only on the amount of air introduced, but on its distribution. The test for distribution is chemical analysis of samples taken in different parts of the room and at different levels. A very good idea of the direction taken by the incoming air can also be obtained by the use of fumes of nascent muriate of ammonia, as above described. In considering the distribution which will probably take place in a given plan, care should be taken not to fall into the common error of supposing that because pure carbonic acid gas is heavier than air, therefore the carbonic acid derived from respiration sinks to the floor, and that special provision should be made to remove it at that point. The law of the diffusion of gases effectually prevents this separation and sinking of the carbonic acid from the mixture of gases expired, and it will be found to be present in about equal proportions in all parts of an inhabited room.

The methods of introducing and distributing fresh air depend to a great extent upon the methods of heating employed; and it is necessary to remember that while good ventilation is a very desirable thing, satisfactory heating is, in cold weather, still more desirable, and must be attained even if the ventilation is interfered with for that purpose. The principal difficulty in the way of securing good ventilation is its cost. In a cold climate satisfactory heating, good ventilation, and cheapness are not compatible; it is comparatively easy to obtain any two of them, but impossible to have the three together. This fact should be fully understood and realized by the physician, for its comprehension will save much time in considering the merits of various patent ventilators and ventilating appliances, which, according to their inventors, produce good ventilation at no expense beyond that of the original cost of the apparatus; which is practically about the same as a claim to have discovered perpetual motion. Patent ventilators are usually cowls to be placed upon the top of outlet {181} flues. I know of none which are superior to the common Emerson Ventilator, on which there is now no patent. In cold weather the air must be warmed to secure comfort; it must be changed to secure ventilation. The changing of the air carries off heat, the loss of which must be supplied by fuel, which fuel costs money. The greater the ventilation, the more rapid the change and the more heat required. It is therefore quite possible to judge somewhat of the merits of a heating and ventilating apparatus--for example, of a school-house--from the amount of fuel consumed; but the conclusion will be precisely the reverse of that drawn by the average trustee, since it will be, that within certain limits the less fuel required the less satisfactory the apparatus.

The evil effects of insufficient ventilation, although very certain and very serious, are not immediate, or such as to attract attention at first, except in very aggravated cases with excessive over-crowding. The power of the organism to adjust itself to surrounding circumstances is very great, and perhaps as great in regard to the endurance of foul air as anything else. Yet this power is greater in seeming than in reality, for at last such air produces disease and shortens life. Its effects are manifested in diseases of the respiratory organs, acute and chronic, and it is now generally admitted that the undue prevalence of phthisis in troops is due to the foul air of the barrack-rooms.

Some persons are much more susceptible than others to the effects of impure air, and will suffer from headache, languor, loss of appetite, etc. where others would experience little inconvenience. Children thus susceptible dread the school-room as ordinarily constructed and ventilated, and their discomfort should be taken into account and guarded against.

Thus far, reference has been made only to those impurities of air due to respiration and lights; in other words, the necessary impurities found in human habitations. The impurities due to sewer gases will be referred to hereafter; they should be prevented absolutely, and not provided for by ventilation. One of the most difficult problems presented to the physician is to determine whether the effluvia from a given locality are injurious to health, and if so, to what extent. These effluvia may be due to certain occupations or manufactures, or they may result from the disposal of excreta, from obstructed drainage giving rise to swamps and the collection of decaying organic matter, and in other ways. The best definition of the term "injurious to health" in this connection is perhaps that suggested by Dr. Ballard--i.e. that exposure to the offensive effluvia causes bodily discomfort or other functional disturbance, continuing or recurring as the exposure continues or recurs, and tending by continuance or repetition to create an appreciable impairment of general health and strength, to render those exposed more liable than others to attacks of disease, and more apt to suffer severely when attacked, and, in the more serious forms, to the direct production of the disease and the shortening of life.

The group of symptoms due to offensive effluvia is, as Dr. Ballard remarks, a tolerably constant one, and consists of loss of appetite, nausea, headache, giddiness, faintness, and a general sense of depression, with, in some cases, vomiting and diarrhoea. But it is usually impossible to prove by statistics that these phenomena are due to a given effluvium complained of, for those who suffer from it are usually exposed to other causes of ill-health, such as poverty, overcrowding, collection of filth, etc.; and, on the {182} other hand, many of those exposed to the effluvium seem to suffer very little, if at all, from their surroundings. And so true is this, that in the carefully prepared report upon effluvium nuisances recently issued by Dr. Ballard, it will be found that as a rule no attempt is made to prove that the effluvia from any particular branch of industry are injurious to health; the test practically applied is that they produce offensive odors.

The legal view of this subject is given in the various decisions as to what should be considered a nuisance, the essence of which is the use of one's own property in such a way as to inflict damage upon, and injure the rights of, another. If a man collects on his own premises, for his own use, any material, such as water or filth, he is bound to retain it within his own premises or to let none of it escape in such a way as to damage others; and this holds good as regards gases, vapors, and odors. The decision of Mansfield, in the case of Rex vs. White, is often quoted approvingly by jurists, viz.: "It is not necessary that the smell be unwholesome; it is enough if it renders the enjoyment of life uncomfortable." But, practically, the question as to whether the discomfort produced is sufficient to produce ill-health will be the one upon which the physician is called to give evidence, and the one also upon which he will find it most difficult to obtain data sufficient to enable him to form a positive opinion.

III. IMPURE WATER.--Of all the various preventable or removable causes of disease to which the attention of the physician engaged in practice in the small towns and rural districts is directed, it will usually be found that the water-supply is the most important, because it is in these localities that it is most liable to become contaminated in such a way as to produce sickness.

All water used for drinking purposes is impure in the chemical sense, since it contains some inorganic matters or salts, and in most cases organic matter also. It is difficult to define precisely what should be considered an impure water in a sanitary sense, and the best we can do is to indicate probabilities in the absence of positive evidence of the production of disease by the suspected water. So far as inorganic impurities are concerned, the most important, from the sanitary point of view, are the salts of lead, magnesia, and lime, but in this country these are so rarely the cause of disease that they hardly require special notice. The physician should, however, bear in mind possibilities of lead-poisoning in some obscure cases which he will meet.

The diseases due to impure water are certain specific fevers, diarrhoeal diseases, and some affections due to parasites which find entrance to the body through this medium. The water-supply is to be suspected in case of prevalence of diarrhoeal disease in a community, and especially if the outbreak be sudden and affect a number of persons and families. Sudden outbreaks of cholera, typhoid fever, or malarial fever, confined to a limited locality, should lead to careful examination of the water-supply. The impurity in water which causes these diseases is supposed to be either organic or the product of organic life, and at present the prevailing opinion is that the really dangerous impurities consist of minute living organisms or {183} germs. It is usual to estimate the impurity of water by the amount of organic matter present, but it is evident that this alone can give no positive information, since by this standard milk and soup would be very dangerous. Much depends upon the character of the organic matter, whether it is derived from the animal or vegetable kingdom--whether it is in a state of fermentation or putrefaction, etc. etc.; but the presence of specific germs in it is the most important part of all, and at the same time the most difficult to ascertain. Nitrogenous organic matter in a state of decomposition is dangerous, yet it does not always produce disease, even when ingested in comparatively large quantity, as in case of "high" game or tainted meat; and it is easy to find instances where water strongly polluted with sewage has been used for a considerable period without producing marked ill effects. It is, however, so extremely probable as to be for practical purposes certain, that water contaminated with the discharges from persons suffering from certain diseases will produce similar diseases in those who drink it, and there is also enough evidence that water containing filth of various kinds either produces or promotes disease to warrant much more attention to this subject than has heretofore been bestowed upon it.

The chemical examination of a suspected water is by no means a simple process, and in most cases had better be referred to an expert in such matters. It is highly desirable, however, that the physician should have sufficient technical knowledge to be able to make a rough analysis at least, if for no other reason than that he may be able to appreciate the results reported by the chemist. As a rule, when a water is so polluted with decomposing organic matter as to be positively dangerous it will have an unpleasant odor, which is best developed by half filling a quart bottle with the water to be examined and shaking it thoroughly. The so-called simple and ready methods which are from time to time advocated in the newspapers, such as the addition of sugar to the suspected water and allowing fermentation to take place, the use of tannin as a precipitant, or the decolorization of a solution of potassium permanganate, are really of very little value and should not be relied upon. In the hands of an expert the best simple method of determining the quality of a water is by evaporation of a known quantity and the ignition of the solid residue. From the amount of the total residue, the quantity left after ignition, the amount of blackening produced, and the odor, a very fair opinion can be formed as to the amount of organic matter present, and whether it is of animal or vegetable origin.

It is not within the province of this paper to describe the methods used by chemists in water analysis, of which the principal are known as the Franklin and Armstrong, the Wanklyn, and the permanganate methods. A careful examination of these methods has recently been made under the direction of the National Board of Health, and a preliminary note of the results, prepared by Professor Mallet, has been published in the Bulletin. From this it appears that the chief value of chemical analysis is, first, the verification of gross pollution, which will usually be detected by the appearance and smell of the water; and, second, in periodical examination of a water-supply to detect changes from the normal or usual character of the water, which may be taken to have a certain local standard of purity. Special importance is attached to the careful determination of {184} nitrates and nitrites in water to be used for drinking, these being the results of oxidation of organic matters, and therefore giving evidence of previous contamination.

Prof. Mallet concludes that "there are no sound grounds on which to establish such general standards of purity as have been proposed, looking to exact amounts of organic carbon or nitrogen, albuminoid ammonia, oxygen of permanganate consumed, etc., as permissible or not. Distinctions drawn by the application of such standards are arbitrary and may be misleading." While this is perfectly true, considered from the standpoint of scientific precision, it does not sufficiently take into account the value of probabilities in these matters, considered as motives to action. It is perfectly true that there can be no fixed standard--that a water which the chemist would report as relatively pure might be much more apt to produce disease than one which he would pronounce impure--but it is nevertheless true that from the results of chemical analysis, taken in connection with evidence as to the source and history of the water, an opinion can be formed as to the danger from its use which is sufficiently reliable to be acted upon in the absence of positive evidence, such as the production of disease.

In many cases the matter must be doubtful, and Prof. Mallet truly says that it will not do in all such cases to forbid the use of the water, for it often happens that this should not be done unless it is absolutely necessary; but there are many other cases in which there is very little doubt, and where action should be governed by the probabilities.

The microscopical examination of suspected waters sometimes gives decided indication as to the nature of the impurities; and it may be that hereafter, in connection with physiological tests, it will become of even more importance than the chemical. To determine the presence of organisms in a sample of water the best method known at present is to kill and coagulate them by means of osmic acid or chloride of platinum, and allow them to subside. This method is of course inapplicable if it be desired to use them for either culture- or inoculation-tests.

Chemists have no uniform system of reporting the results of their analyses, some using grains per gallon, U.S. or Imperial as may be, and others parts per hundred thousand or per million of the water. It is therefore difficult to appreciate the value of the figures as given by them. The following, in parts per 100,000, will enable the practitioner to form a general estimate of the character of analytical reports; but the opinion in individual cases is so modified by the coincident amounts of chlorine, ammonia, nitrous and nitric acids, that the experienced sanitarian only is qualified to put on the results an estimate which shall be in accordance with our present knowledge of such matter:

Upland Surface-Waters. Allowable. Doubtful. Impure. Total organic elements to .4 .4 to .6 Over .6 Oxygen required to .3 .3 to .4 " .4 Albuminoid ammonia to .015 .015 to .025 " .025

All Other Waters. Total organic elements to .2 .2 to .4 Over .4 Oxygen required to .15 .15 to .2 " .2 Albuminoid ammonia to .010 .010 to .015 " .015

{185} In connection with impure water should be mentioned impure ice. Ice is purer than the water from which it forms, but if cut on a foul pond it will itself be foul, and the vitality of some microscopic organisms is not destroyed by their being frozen, as is shown by the fact that samples from the centre of blocks of ice will inoculate sterilized infusions with the germs of putrefaction, precisely as the water of which the ice is composed would have done before it was frozen. Disease has been traced to impure ice, and it may be that it is more frequently due to this cause than has heretofore been supposed; at all events, it is well to bear the possibility in mind.

The subject of impure water will be further considered in speaking of habitations.

IV. CLIMATE.--The literature of the effects of different climates upon the human body is very extensive, following the general rule that the less positive or precise knowledge there is upon a given subject the more will be written about it. Of all animals, man seems to adapt himself most readily to the extremes of climate; and, although it is commonly supposed that a tropical climate is injurious to those coming from cooler regions, yet it has been found that where he takes the same precautions to ensure cleanliness, pure water and air, and proper food, the European does not have a higher rate of mortality in Algeria or in the East or West Indies than he does at home, if the effects of cholera and yellow fever be excepted.

Dr. Parkes defines the effect of climate upon the human body to be "the sum of the influences which are connected with the solar agencies, the soil, the air, or the water of a place;" in other words, he makes it nearly equivalent to the locality or the environment. By "climate" we understand, commonly, the sum of meteorological influences, the most important of which, as regards health, are temperature, humidity, and wind. The effects of temperature in producing disease are often confounded with the effects of change of temperature, which last is perhaps the more important of the two, and should be specially borne in mind in advising climato-therapy for chronic or wasting diseases.

The influence of climate in causing disease, although well known for over two thousand years, has not led to much effort to avoid or prevent effects which are accepted as inevitable by the great majority. It is true that in the effort to secure physical comfort by houses, clothing, artificial heat, and the like, much hygienic work has been done, and the steadily increasing tendency on the part of all who can afford it to seek rest and comfort at the seaside or in the mountains during hot weather is no doubt due, in part, to the fact that experience has shown that the money expended in thus securing health and strength is a good investment. It is unfortunate that "health resorts," so called, do not always prove to be such: they become fashionable, overcrowded; the arrangements for the disposal of excreta are cheap makeshifts, leading to soil- and water-pollution, until finally an epidemic of diarrhoea or typhoid fever occurs, with the usual results.

The consideration of climate as a therapeutic agent belongs with the articles relating to the several diseases to which it is applicable. The great desideratum wherewith to place this subject upon a scientific and practical basis is a system of reliable returns of the deaths, and if possible of {186} certain diseases, throughout the country, and especially at those points most in vogue as health resorts.

V. HABITATIONS.--That a man's health depends very much on the character, condition, and location of his dwelling-place is now so generally admitted that in many cases where a physician is called in he will be asked whether he thinks the disease has been caused by any peculiarity about the house or the bedroom of the patient. And a careful examination will usually discover in one of them several evils to be remedied, although their connection with the case in hand may be very doubtful. There are very few homes properly constructed from a sanitary point of view; and, although we may not agree with Dr. Wilson, that "the modern prison is in all sanitary essentials the best existing type of what a healthy dwelling ought to be," it is nevertheless certain that the health of the inmates is much more carefully consulted in planning a penitentiary than it usually is in planning a college, a hotel, or a dwelling-house. Matters are gradually improving in this respect: the worst of the tenement-house rookeries and fever-nests in most of our large cities have been improved or abolished, and our wealthier citizens are beginning to pay some attention to their house-drainage as well as to the pattern of their mantelpieces. But the great majority of men are still careless and negligent as to the sanitary condition of their homes, and probably two physicians out of three live in houses in which numerous defects would be pointed out by a sanitary engineer--defects of which they are themselves more or less aware. The majority of people in our large cities under existing conditions cannot afford to have healthy houses, and the great causes of the excessive mortality, and brevity of life, in all such cities, are poverty and overcrowding, the latter resulting from the former. The problem as to the best mode of improving the sanitary condition of the tenement-house population does not, however, come before the practising physician for special consideration, and need not be considered here. Nor is the physician liable to be consulted with regard to the sufficiency, from a sanitary point of view, of the plan of a house yet to be built, although he will occasionally be asked as to the healthfulness of a proposed site. The questions which he will be asked are such as the following: "Is the cause of this particular case of disease in the house, or connected with it? and if so, what is it?"--"Do you think this is a healthy house?"--"Is the location a healthy one?"--"Is it necessary that I should give up this house to preserve the lives and health of my children?" While it is, of course, often impossible to answer with precision such questions as these, an answer of some kind must be given; and this should not be a mere random guess, but based on a deliberate estimate of the probabilities in the case. The healthfulness of a house is to be judged of, in part, from its history, if it be possible to obtain any; in part, from such facts as can be discovered by a careful examination of the premises and vicinity. The sanitary history of a house is the history of the diseases and deaths which have occurred in it, together with a set of plans showing the precise location and character of the house-drainage and of its fresh-air supply. Such a record is in most cases, unfortunately, not attainable, although to a person proposing to buy or rent a house it would often be quite as important as a record of title. In a well-organized health-office it should be possible to ascertain the number and causes of the deaths which have {187} occurred in any given house or square in the city, and also the character and location of its drainage and sewer connections. Such records are especially valuable in an investigation of an outbreak of disease in a community.

The sanitary inspection of a house includes the site and the building itself. The character of the site is mainly determined by its dryness, by the presence or absence of organic matter in the soil, and by its porosity taken in connection with the character of the vicinity. One-third of the volume of some soils consists of air, and all dry soils and rocks contain a much larger quantity of air than is commonly supposed. The influence of soil upon health is exerted mainly through the media of water and air, but it also affects temperature and vegetation, being an important factor in climate. Residence on a damp soil has a tendency to produce diseases of the lungs, and especially phthisis; but how it does this is unknown, though it would be easy to construct a plausible theory in connection with the supposed causation of phthisis by a bacillus. The practical point for the physician is, that the prevalence of phthisis in a locality, even if it be so limited as to comprise but a single house, should cause suspicion and investigation as to the character of the soil-drainage. Soil-moisture is also an important factor in the development of periodical fevers, and the effect of thorough drainage in diminishing malaria is now generally understood.