Sunlight And Air

Most important for the preservation of health and vitality are sunlight and air. They are just as necessary for growth and perpetuation of life as are liquid and solid food. “When the sun does not enter, thy physician enters,” says an old proverb. It has been found that the greatest mortality occurs in the narrow streets of cities and in houses having northern exposure.

The inhabitants of southern mountain slopes are stronger and healthier than those living on the northern sides. Inhabitants of secluded valleys where the sun rises late and sets early are generally afflicted with peculiar diseases, chiefly due to a lack of direct sunlight and its salutary power to dissipate and decompose noxious vapors that accumulate in dark and low places.

The sun indeed is the great and ultimate source of all power that manifests itself in the inorganic as well as in the organic formations of matter. Plants require sunlight above all for the completion of their complicated organic combinations. While the lowest species of organic life, such as fungi, are capable of developing darkness, the higher plants, which principally support animal life always depend upon the rays of the sun for the processes of assimilating the elements of soil and atmosphere. They require especially the non-illuminating ultraviolet rays, which we know to be most active in the production of electrochemical effects.

Likewise, the animal body is to a large extent directly dependent upon sunlight for its growth and healthy development. It is a well-established fact that, as the result of an insufficiency of light, the fibrine and red blood corpuscles become diminished in quantity, while the serum or watery portion of the blood is increased, inducing leukemia, a sickness characterized by a great increase in the number of white blood corpuscles. A total exclusion of the sunlight induces the severer forms of anemic diseases, originating from an impoverished and disordered state of the blood.

Of the many experiments that have been made so far to demonstrate the beneficial effects of sunlight, the one conducted by John Blaytonis is the most remarkable and significant. In order to determine whether the indirect or diffused daylight, perhaps during a longer period of time, has the same effect as the direct sunlight, he selected twelve bean plants of the same variety and in the same stage of development.

Then he planted them near one another in such a way that six always had full direct sunlight, while the others received only the diffused daylight. In October, the pods were harvested, and the weight of those grown in the shade or diffused light compared with that of those exposed to the sun rays was found to be in the proportion of 29:99; that of the dried beans 1:3.

This result was expected, but in the following year, when all the plants grown from the same seed received the full amount of the direct sunlight, the surprising fact was ascertained that those which had been raised in the shade yielded only half the amount of the previous year’s harvest, while in the fourth year they blossomed but did not mature. The deprivation of direct sunlight during one summer weakened the stock to such a degree that the species became extinct after four years.

The lesson of this experiment may be applied with great benefit to humans and their daily habits. The highly beneficial effect of sunbaths, if judiciously taken, is demonstrated by the above example in the best possible manner. A dwelling place that admits the sunlight during all hours of the day is, therefore, one of the first conditions for the preservation of health.

Statistics show that the tenament house districts of the large cities to which sunlight has very slight access have the greatest infant mortality and have many cases of rickets and tuberculosis. If it were not for the constant renewal of the population from the rural districts, the city dwellers, especially the poorer classes, would die out in the course of a few generations.

All mothers should realize the importance and benefits of sunlight and use every opportunity to admit the direct rays of sun to their living and sleeping rooms whenever and wherever this is possible. Sunlight and fresh air are primal factors on which the normal development and health of the child depend.

Frequent exposures of the naked body to the sunlight will greatly assist the system in the performance of all physiological functions. It will especially insure an even distribution of the blood. Such an adjustment of the circulation is necessary for the normal functioning of all organs. People should make it a practice to expose their nude bodies frequently to sunlight and fresh air in order to keep in the best possible physical condition. Public parks should have enclosures where sunbaths and airbaths can be taken, and these should become an adjunct of every modern progressive city.


Sunlight can kill cells in our bodies if the cells are exposed too much to the very intense rays of the sun. Moderation and discrimination should always be exercised. Sunbaths are best taken in the morning, and an eastern exposure should be selected for the purpose.

Equal attention should be paid to a continuous supply of fresh air during day and night. Not many persons seem to realise the absolute necessity of the electrifying, life-giving oxygen for the maintenance of vitality and health It has been only a century and a half ago (1774) since the English scientist, Priestly, and the French scientist, Lavoisier, discovered that we live by means of a chemical process of combustion in which the blood unites with the inhaled air, yielding the products of combustion that we exhale as aqueous vapor and carbonic acid gas.

This chemical action corresponds to that which we find in the case of a burning candle or a lamp fed with oil. If the supply of air is cut off, we will be suffocated, just as the flame of a lamp is extinguished if the air is prevented from passing to it. A person may live more than sixty days without food and a few days without water, but when deprived of air or oxygen, they die within a few minutes. This proves that pure air is the most necessary of all the essentials of life.

Atmospheric air consists of two gases, viz.: nitrogen and oxygen; the former serves only to dilute the oxygen. Besides these two elements, the air always contains some aqueous vapor, carbon dioxide and ammonia. On an average, 100 volumes of air contain: 78.35 vol. of nitrogen (N); 20.77 vol. of oxygen (O); 0.84 vol. of water vapor (h3O); 0.04 vol. of carbon dioxide (CO2); 0.0001 vol. of ammonia (NH3); and traces of other gases (ozone, etc.).

There are also various kinds of microbes in the air, according to moisture and temperature, causing fermentation and chemical disintegration of organic substances. The composition of air, i.e., its proportions of nitrogen and oxygen, is the same all over the surface of the earth. The degree of moisture or humidity in the air varies according to location and temperature. Carbon dioxide is always present, even in mid-ocean and forests, but its quantity is very small, ranging from three to four parts per ten thousand by volume.

In closed rooms, however, where numbers of persons are present and at the same time gas and coal are burned, the percentage of carbon dioxide rapidly increases. At the same time, the air is filled with other more poisonous gases, such as ammonia and albuminoid ammonia, while the amount of oxygen is gradually lowered. All these facts should be seriously considered in the proper ventilation of living rooms, schoolrooms, etc. The following table gives the average amount of carbon dioxide in 10,000 parts found in the air of different localities:

Ocean and forests0.3
Cities, open streets0.4 to 0.5
Bedroom during night,
Window partly open
Bedroom during night, Window closed1.2
School-rooms1.5 to 3.0
School-room, 70 occupants at close of school hrs.7.2
Churches, during services3.5 to 7.0
Churches, if heated by furnaces20.0 to 30.0
Theatres, crowded meeting rooms25.0
Workshops, ill-ventilated30.0

These figures show how little attention is paid to proper ventilation, and they explain the constant increase of pneumonia and similar diseases. The importance of pure air becomes still more obvious if we consider the wonderful anatomical structure of the respiratory organs. The lungs, into which the air is drawn, consist of two rounded, oblong, somewhat flattened masses of cellular substance.

They are situated in the cavity of the chest, which communicates with the atmosphere through the windpipe (trachea). The trachea, as it descends from the throat, branches off into large tubes, and these branch again and again into smaller and still smaller ones and finally into hairlike vessels.

Through these the air penetrates into the remotest parts of the cellular substance. Around each visible extremity nearly 18,000 cells are clustered, each of which is connected through these minute
tubes with the external air. The cells vary in size. They have an average diameter of about one one-hundredth inch. Their total number has been estimated at about six hundred million. The wall of these cells is very thin; they are mere air vesicles.

The internal surfaces of all these cells together form an area of about one hundred sixty square yards of thin cell-wall. Over the whole of this surface, minute blood vessels branch out, almost entirely covering it. Along these tiny vessels the blood continually flows and, in its course, absorbs through their walls the oxygen of the inhaled air.

It is in the delicate membrane of these blood vessels that the change from venous into arterial blood is effected. The venous blood must be changed continually because it is an impure fluid containing matter that has already served for the support of life in the various parts of the body. Carbon dioxide and other gases are given off, and the oxygen of the air enters, the cells of the lungs and is absorbed by the minute vessels that spread over the cell walls. Within these vessels the oxygen combines directly with the hemoglobin of the blood, and by means of the action of the heart, proceeds with it in ceaseless currents through the arteries and veins.

To a certain extent the skin also absorbs oxygen and exhales carbon dioxide, the amount being about one-thirtieth of that excreted by the lungs. Besides, the skin gives off other gases, water and solid matter, amounting to from one to two pounds during the day. In summer people perspire more than in winter. During exercise or exertion more water is lost than at rest.

All parts of the skin should be brought frequently in immediate contact with the external air. There are several million pores in the skin acting as little sewers through which various waste products of the system are constantly excreted. The clothing and particularly the underwear should be porous to permit free circulation of the air. Closely woven linen or cotton shirts, if covered with heavy woolen clothes, cause the retention of waste matter that is partly reabsorbed by the system and thrown back on the lungs and kidneys, overworking and weakening these organs.

As has been shown that in ill-ventilated and often tobacco-laden public halls, churches, schoolrooms, theatres and workshops, the air thrown off from the lungs is rendered still more noxious by the emanations of the skin. People, on leaving such places, feel the contrast between the inside and outside air and erroneously blame the fresh air as being responsible for their “colds,” which are but the result of the inhaled poisonous gases and their unsanitary methods of living in general.

Many persons sleep with closed windows because they cherish the old delusion that “night air is dangerous.” After a few hours they begin to breathe the exhaled air over again. In the morning they get up with a “tired feeling” and have to resort to “eye-openers” which make their condition still worse. It is during the night when we are at rest that the lungs redouble their efforts to inhale the life-giving oxygen to recharge the human dynamo.

It is therefore even more essential to insure an adequate supply of pure air during the night than in the daytime. There is absolutely no danger of “catching cold” from cold, fresh air. On the contrary, the bodily heat, which results from combustion, is increased by an abundant supply of oxygen.

A “cold” is really but an effort of the system to cast out impurities, chiefly through the mucous membranes of the throat and nose. Few persons realize that the amount of air taken up by the system daily outweighs that of the solid food.

The changes that have taken place in the composition of the exhaled air are indicated by the following table:


Inhaled Air

Exhaled Air


Volumes percent







Carbon dioxide



Exhaled air is also saturated with water vapor and contains traces of ammonia and organic matter varying with the diet, climate and occupation of the individual. Under normal conditions, if the blood is rich in the essential organic salts, the lungs absorb through the medium of the red blood corpuscles twenty-four and one-half ounces of oxygen during twenty-four hours, while they give off twenty-eight ounces of carbon dioxide retained in the lungs. Children need relatively more oxygen than adults, as the tissue changes are more active during the growth of the organism.

The adult man of average weight at each inhalation draws in about one pint of air, and during twenty-four hours he averages fifteen respirations a minute. Thus he takes in two gallons of air a minute or 120 gallons an hour, amounting to about 2,880 gallons or 384 cubic feet a day. This volume of air would fill a room measuring a little over seven square feet.

The weight of this volume is about thirty pounds and contains about seven pounds of oxygen, as the latter forms 23.2 percent of weight of the atmosphere. Of the total amount of inhaled air, the human body takes up oxygen at the rate of 4.78% by volume or 5.25% by weight, while exhaled air contains 4.34% of carbon dioxide by volume or 6.5%, by weight.

Of the total amount of oxygen inhaled, the body generally absorbs from eight to ten ounces (one-third) during the activities of daytime, while during sleep in the open air or in well-ventilated rooms, the quantity may be doubled to sixteen ounces.

It may be noted here, incidentally, that the absorption of oxygen depends largely upon the number of red blood corpuscles in a given quantity of blood. During severe muscular exertion, respiration is also increased in frequency and in depth, and the volume of air exchanged may be from five to seven times greater than during a period of rest.

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Experiments have been made by German scientists showing the effect on oxygen consumption of walking on a level and climbing. The following figures give the quantities of oxygen consumed during one minute, the subject being a man of 125 pounds weight:

Form of Exercise

Oxygen Consumption

Standing at rest

16 cubic inches

Walking on a level

48 cubic inches


78 cubic inches

It appears that walking increases the consumption of oxygen threefold and climbing nearly fivefold over that consumed at rest. These facts illustrate the influence of muscular activity upon the bodily metabolism and the incidental purification of the system from waste matter. Regular exercise in the open air during all seasons of the year is one of the most important factors for the preservation of health and the prolongation of life.

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