CHAPTER II. THE HYGIENE OF HABITATIONS. (Part 1)

CHAPTER II. THE HYGIENE OF HABITATIONS. Among the factors of external environment there are few which play so important a role in the life of man as his habitation. Housing conditions are power- ful factors in the preservation of human life and the prevention of disease. There is an intimate relation between the disease and death-rates of populations and the conditions of their housing. The density of population in areas and localities, congestion and overcrowding in houses and many other factors directly influence the health of the population. The house plays also an important role in the safety of its inhabitants, w^hile the proper fire protection of the house is a direct factor in the elimination of dangers of fires to life and limb. The diseases which are associated with housing con- ditions are those due to transmission by the bites of insects and parasites, those due to the emanations of gases and also those due to bacterial origin. Bron- chitis, influenza, tuberculosis and pneumonia are dis- eases closely associated with housing conditions. Several diseases due to intestinal bacteria, such as typhoid fever, dysentery, cholera and hookworm dis- ease are often associated with defective conditions SAFKIY AM) Fll;i-: rii'OTECTIoX 25 ill lumscs which t'axor the tiaiisinissioii of inrcdiNe hjictcri;! and (hsscniinat ion of (hscasc. liiiproxcnients in housing conditions, the (h'crcasc of (lcn^it> and conucst ion, |)rc\ cnt ion of o\ crci'dw ihnii;, inii)ro\cd (ii'c protection, hcttcr hji;htin^ and ventila- tion of hon'^o. iinpro\c(l sanitarx' conxcnicnccs and comforts, ha (' always led to hettcr liealt li conditions of the jjopnlation. The iinj)ortant factors in honsing conditions whidi will he hriefly discnssed arc the f()]|owin<i;: Safety and fire protection, liu'ht and illnminat ion, air and Ncntila- tion, heating, water sup])ly, dis|)osal of sewage, phnni)- in^ and disj)()sal of honse wastes. SAFETY AND FIRE PROTECTION. "^riie safety of house and inhabitants de])cnds upon the pro])cr construction of the house. Houses must he constructed of proper materials in a workmanship manner i!i oidci- to i)re\eut accidents due to insecure walls, falliu<; plaster from ceilinf];s, trij)piuf; over i)ad stairways and other accidents so frinpicnt in hadly constructed liouses. Loss of life or danjiers to life and liinh from lii'cs in iiouses ma' i)e pre\cntc(l hy Imildini,' houses of Hrc- resistinj; and firei)ro(»f nuiterials and l)y the provision of ample exits to enable the inhal)itants to escape from the house during; fires or i)anic. The necessity for con- strn( tinu' lioines of many stories in densely po|)ulatcd cities has led to the increase of dangers from tires in multiple dwellinjis and tenement hous<'s. {'rou'rcssixc hon-^iufj legislation demands the construction of hr)uses 26 HYGIENE OF HABITATIONS of fireproof materials, the enclosing of all shafts, such as elevators, dumbwaiters, etc., by fireproof partitions provided with self-closing fireproof doors. In practi- cally all modern cities the construction of frame dwellings has been prohibited in the city area. Exit in case of fire is provided for by means of wide, properly lighted, fireproof stairways and also by the construction of special fire escapes outside of the build- ing, which serve as an exit in case of emergency. Fire escapes are constructed of iron and consist of balconies in front of one or more windows in each apartment, these balconies on each floor being connected with iron stairways facilitating the descent of the inhabitants of each floor to the ground or their ascent to the roof by means of goose-neck ladders. LIGHT AND ILLUMINATION. Natural Light. — Sunlight is essential to the growth of animal and vegetable life; it acts beneficially upon health, stimulates the metabolism of the body and assists in the oxygenation of the blood. Sunlight is also a powerful germicide and disinfectant; it kills low organisms, fungi, and moulds, is capable of destroying tubercle bacilli within a short time, and is therefore indispensible in human habitations. Habitations with- out direct sunlight are damp, cold, and unhealthy. The amount of natural light within a house depends on: 1. The location and aspect of the house. 2. The sources of light. iJciiT AM) iLi.r\ii.\ri(>\ 27 '.. Tlu' locjitioM iilid si/.c (if the (tp<'niiius tliioiiuh whic-li is peut'tratos. 4. The character of windows and of surface within the house. Direct rays of the sun give more Hglit tlian re- flected hghts from adjacent surfaces, walls, trees, etc. Greater light is obtained through horizontal openings on top (if the house than from windows in vertical walls. The intensity of light within a house depends also upon the character of the window glass. There is a loss of light of 50 per cent, through milk glass, 10 per cent, through double glass, and S ])er cent, through plate glass. Prism or ribbed glass, by distriliuting and reflecting the rays of the light e\enl.- Tlu-oiigh the room, increases the amount of light. The window area of a room should not be less than 10 per cent, of the floor area; one square foot of glass surface should be allowed for every 70 cubic feet of interior space. Piers between windows should be narrow; window tops should extend to the ceiling, or at least to within li inches of it. Plate glass is best for transmission of light, unless prism glass is used. Smooth, light, or light colored surfaces of iimer walls and floor and ceilings increase the amount of relle(te(l light. Artificial Light.- Artificial illumination in the hou-;e is obtained from tallow and ])aralHn candles, oil or alcohol lamps, water-cooled or acetylene gas, and from electricity. The value of artificial illumination de|)en(ls upon its source, quality, intensity, heat j)roduction, impurities generated, safety and cost. 28 HYGIENE OF HABITATIONS The l)est light is that obtained from electric current through tungsten lamps. Acetylene gas may produce a very intense and brilliant light of from 20 to 160 candle power. The intensity of other lights depends on their material, the character of the burners, etc. Welsbach lights are made of mantles impregnated with earthy silicates, which become incandescent upon slight heating. They give from 60 to 120 candle power. All illuminants, except electricity, produce much heat and give off some impurities, such as carbon monoxide, carbon dioxide, sulphur compoimds, am- monia compounds, smoke, soot, and moisture. Acetylene Gas. — Acetylene gas (r2H2) is produced by mixing water with calcium carbide, and during this process much heat is evolved. Special generators are manufactured for the production of the gas, and, contrary to the current opinion, there is little danger from explosions, as calcium carbide is not explosive either by heat or by concussion. The pipes used for ordinary gas illumination may also be used for acety- lene lights, but the openings of the tips of the burners must be smaller. The light is intense, steady, white, and cheap, and is well adapted for houses in rural com- munities or wherever there are no central plants for the manufacture of electricity or coal gas. Coal Gas. — Coal gas is made by heating bituminous coal in air-tight vessels. During this process the compounds of hydrogen and carbon are transformed into other gaseous and solid products. The refined gas contains about 50 per cent, of hydrogen, 35 per cent, of marsh gas, 6 per cent, of carbon monoxide, and 9 per cent, residue. Li(;nr am) ii.i.imi.\ .\ri<).\ _'.) Water Gas.- Water iras is maiiufacturrd fntin anthracite coal, steam, and i)etr()leiini l)y a compli- cated i)r()cess. The refined product contains :')() \n-r i-ent. of carhon monoxide; :'..") ])er cent, of lixdro^en, •_M) per cent, marsh jjas, and lo ju-r cent, residue. Because of the greater amount of carbon monoxide, water gas is more dangerous to life and health than coal gas. The inhalation of even small amounts of water gas is injurious. Large amounts may become fatal because the carbon monoxide combines with the hemoglobin of the blood and forms an insoluble compound. Coal gas and water gas are manufactured in central plants, from which they are conducted through iron tubes and pipes under the streets into houses, and through a network of smaller iron pipes throughout the houses. The gas-service pipes are made of best wrought iron with malleable iron fittings. The house service should be provided with main and secondary stop-cocks, and meters to measure the amount of gas consumed. The gas-service system must be ])erfectly air-tight, should be exposed and readil' accessible, and should be tested for air-tightness by ajjpropriate tests before use. Gas fixtures are of various shapes and \ alue>. The intensity of illumination greatly depends on the char- acter of the burner, .\rgand and Welsbach burners are the best. Too intense or too l)rilliant light, (-nising glare, may be the direct cause of serious affections of the eye. For the prevention of glare, lamj*-- >hould be provided with proper shades, globes, etc. 30 HYGIENE OF HABITATIONS AIR. Air is a compound gas, a mixture of several gases. Its chemical composition is as follows: Nitrogen, 78.09; oxygen, 20.94; argon, 0.94; carbon dioxide, 0.03; with traces of other gases, helium, kryton, neon, xenon, and hydrogen. The quantity of nitrogen is constant, while the quantities of oxygen and carbon dioxide vary accord- ing to different conditions. In the outside air the variation of carbon dioxide is between 0.03 in the very purest mountain air to 0.04 in the air of city streets. The amount of oxygen does not vary much in the outside atmosphere. Air, like all gases, diffuses itself through space, and its weight is due not only to its chemical constitutents, but also to its physical condition, especially to its tem- perature and humidity. The lower the temperature of the air, the heavier it is. Warm air is lighter than cold air. As the temperature of the air at some places is much lower than at other places this difference causes variations in weight and produces a general motion of air through space, a motion which is often perceptible, and when rapid, is known as wind. Air also contains a certain amount of water in the form of moisture. The amount of moisture depends upon the temperature of the air. The higher the tem- perature the greater is the amount of moisture that the air can absorb. When air is saturated with mois- ture, that is, when it contains all the water it can absorb, the excess of moisture is deposited in the form of dew; it has reached then what is known as the Ain :5l " i\c\ point." Tlic utmost amount of moisture; wliicli air nia' contain witliout reacliinjij tlic drw i)<)int is called (ihsoJiifr hnniidHi/. Tlie difference in tlie amount ot" inoistiu'c wliicli air at a .t,M(Mi temperature ma' actiiall\ contain, and that which it nuist contain in order to reacli al)soIiite saturation, is called rchdire humidity. Impurities in Air. .\ir may contain certain impurities. These may consist of dust of mineral, metal, vegetable, or animal origin, or of various gases, the most common of which are carbon dioxide (CO"), carbon monoxide (CO), etc. There arc nian\ sources of these impurities, sucli as artificial illumination, artificial lieating, dust matter from outside or from the inside of the house, dust and debris from the ^•arious processes and work carried on within the house. Perhaps the most impor- tant source is the presence of domestic animals. The changes which are i)roduced by the i)resence of human beings are the folloAving: (1) A diminution in the ])ercentage of oxygen, (2) an increase in the per- centage of carbon dioxide, (3) an increase of volatile odoriferous organic products, (4) a possible increase in the number of bacteria and microorganisms in the air, (.3) an increase in the temiH-rature, and ((')) an increase in the relati\e huniidit' of the air in the room. Condjustion and illumination within the room oi' shop ])roduce changes in the air acconling to the character and source of the combustion, the most important changes being the increase in temperature and lunniility ami tlir addition of certain gases, such as (();;, ( (), and others due to the processes of com- bustion and illumination. The physical and chemical processes going on witliin the shop add a large amount 32 HYGIENE OF HABITATIONS of (lust from the processes amcl materials used, and sometimes gases aud fumes, due to certain chemical processes, are produced. All these additions to and changes in the normal consistency of the air are usually regarded as air impurities and have a greater or lesser effect upon the human beings within the confined air spaces. The Influences of Impurities in the Air upon the Health. — Some of the impurities within the house may have no deleterious effect. Others, in the form of dust, etc., may become injurious when their quantity is too large or when they are of a poisonous nature. Certain germs and bacteria may be found in the dust, and other impurities in the air may also become dangerous to health. Of the gaseous impurities, car- bon monoxide (CO), from leakage of illuminating gas or from processes of combustion, is very dangerous, as even a small quantity of this gas is poisonous to • human beings. In another place^ I have summarized the present opinion on the character and effects of confined air as follows : 1. That confined air in living-rooms and in work- shops differs from normal air in the following respects: (a) Decrease in percentage of oxygen. (6) Increase in percentage of carbonic acid (CO2). (c) Persence of certain volatile odoriferous organic products. {d) Presence of microorganisms and possible pres- ence of infectious bacteria. ' The Modern Factory — Safety, Sanitation, and Welfare. By George M. Price, M.D., p. 162. AIR 33 {e) l"'rc(|UtMit atlditinii of dust, gases, jiikI fuuu'S. (/) Iliglu'r rate of t«'in|»«'riitiin'. (g) Increase in amount of nioi>turf. ■J. That ordinary dt'creasc of oxygen as fniuid in inhal)iti'd rooms and sliojis ])rol)al)l\ docs not t'xcrt any dck'tcrious influiMur on tlir jH'rsons witliin them, o. Tliat an increase in tlie contents of carbonic acid (COo) from 4 parts to lo and up to KHI part- in lO.OOO volumes is not (hingerous to health. 4. That it has not as yet been ])ro((l that the pres- ence of orjianic matter in confined air has an important heariui: ui)on tlic health of the persons therein, althoufjh a j)roh)njied breathing of a lariie (piantitx' of volatile maitxlorous products ma.\ be followed by nausea, loss of ajipetite, and general malaise. ."). That the presence of dust, gases, and fumes is extremely dangerous in proporti(^n to their kind, char- acter, and (juantity and tiic condition of i)odily resist- ance of the workers. (). That while it is possii)le tliat tubcrculo>i- and some other bacterial diseases ma' be due to aerial infection, the probability of such infection is not great. 7. That the ill etfects commonly- ascribed to impure, confined air of ill-ventilated rooms and shops are due not so nuich to tlic chemical iini)uritics in the air, but to the physical i)ro|)erties, such as increased temjH'ra- turc, higher rate of humidity, and stagnation of the air surrounding the body. 5. That an increase of the temperature of confined air in workshops abo-e 70^ l*'., and ])articularly an increase in the wet-bulb reading of the therm(»meter above the same degree. i> jjrobably injurious to health 3 34 HYGIENE OF HABITATIONS if maintained for too long periods, and may cause fatigue, lassitude, decreased metabolism, anemia, and loss of resistence, predisposing the workers to acute and chronic diseases. VENTILATION. By excluding the outside air by means of walls, ceilings, and floors, artificial conditions are created. Houses are habitable only as long as some provision is made for the exchange of air from the outside to the inside, and vice versa. The room air which becomes impure must be replaced by a supply of fresh air from without. This interchange of air is called ventilation. The quantity of air which each individual needs depends on a great many conditions besides the air space within the house and the rate of influx. The older hygienists based their calculations on the carbon dioxide content and determined the- amount at 3000 cubic feet of air per hour. They regarded the carbon dioxide contents of the room air as an index to the general purity, and held that whenever it exceeded 0.06, the room air was bad. The degrees of temperature and relative humidity are at present regarded as a more important index of the condition of the air in a room. Natural Ventilation.^ — The main factor in ventilation is not so much the amount of space in the house as the amount of air which enters by various means. Air is a gas, and as such rapidly diffuses through the house. As most of the materials of which houses are constructed are porous, a certain amount of air enters and leaves through the walls, floors, and ceilings. A certain vi'jMii.Aiio.x :;.") aiiiotmt ;ils() passes tliroii.^li tlit- cracks, crcxiccs, aiitl other sli<ilit (>i)ciiiii<;s which arc tdiiiid in c\cii the best-(H)ii.striictc(l lioiiscs, near the \viii(h)us, doors, etc. The motion of air (hie to (JitVerences of teinpcratun' ami, conse(|iieiitl-. of weight is also an iiii])ortant factor in v<Mitihition. The cohler outside air tends to How into the house while the warmer, lighter air in the rooms tends to flow out of the house. The greater the dilVereiicc in temperature the greater the exchange of the air. There is therefore some ventilation in every house: (1) through the ])orosity of the building materials and the diiVusion of the air through these materials, and Cl) through variotis openings due to faiih.\ construction, etc. ( himueys also contribute largely to the interchange of air and form flues through which the warm air passes. When the wind blows over the openings of the chimneys it creates a suction or aspiration and large quantities of air are drawn out. The occa- sional opening of doors and windows also serves to allow the influx (»f outside air and the flowing out of the room air. The value of windows for xcn- tilation depends, of