A distinguished surgeon[14] of Leeds, England, goes somewhat further in praising pure air than most of his contemporaries. "Be it remembered," says he, "that man subsists more upon air than upon his food and drink." There is some novelty in this remark, I admit: but is it not truthful? Men have been known to live three weeks without eating. But exclude the atmospheric air from the lungs for the space of three minutes, and death generally ensues. We thus see that life will continue with abstinence from food three thousand times as long as it is safe to protract an atmospheric fast.
Let us take another view of the subject. Men usually eat three times in twenty-four hours. This is all that is necessary to, or compatible with, the enjoyment of uninterrupted good health. But we involuntarily breathe nearly thirty thousand times in the same length of time. We need, then, fresh supplies of pure air ten thousand times as often as it is necessary to partake of meals. Is it not apparent, then, that man subsists more upon air than upon his food and drink?
The atmosphere which we so frequently inhale, and upon which our well-being so much depends, surrounds the earth to the height of about forty-five miles. The surface of the earth contains about two hundred millions of square miles, and it is estimated that there dwell upon it eight hundred millions of inhabitants. This gives to each individual about eleven cubic miles of air. But the air is breathed by the inferior animals as well as by man. It is also rendered impure by combustion. If by both of these causes ten times as much air is consumed as by man, there is still left one cubic mile of uncontaminated atmospheric air to every human being dwelling upon the surface of the earth. This would allow him to live more than twice the age allotted to man, without breathing any portion of the atmosphere a second time. And still, as if to avoid the possibility of evil to man on this account, the beneficent Creator has wisely so ordered, that while we do not interfere with the laws of Nature, there is not even the possibility of rebreathing respired air until it has been purified and restored to its natural and healthful state; for carbonic acid, the vitiating product of respiration, although immediately fatal to animals, constitutes the very life of vegetation. When brought in contact with the upper surface of the green leaves of trees and plants, and acted upon by the direct solar rays, this gas is decomposed, and its carbon is absorbed to sustain, in part, the life of the plant, by affording it one element of its food, while the oxygen is liberated and restored to the atmosphere. Vegetables and animals are thus perpetually interchanging kindly offices, and each flourishes upon that which is fatal to the other. It is in this way that the healthful state of the atmosphere is kept up. Its equilibrium seems never to be disturbed, or, if disturbed at all, it is immediately restored by the mutual exchange of poison for aliment, which is constantly going on between the animal and vegetable worlds. This interchange of kindly offices is constantly going on all over the earth, even in the highest latitudes, and in the very depths of winter; for air which has been respired is rarefied, and, when thrown from the lungs, ascends, and is thus not only out of our reach, whereby we are protected from respiring it a second time, but this (to us) deadly poison falls into the great aërial current which is constantly flowing from the polar to the tropical regions, where it is converted into vegetable growth. The oxygen which is exhaled in the processes of tropical vegetation, heated and rarefied by the vertical rays of the sun, mounts to the upper regions of the atmosphere, and, falling into a returning current, in its appointed time revisits the higher latitudes. So wisely has the Divine Author ordered these processes, that air, in its natural state[15] in any part of the world, does not contain more than one half of one per cent. of carbonic acid gas, although, as already stated, air which has been once respired contains eight and a half per cent. of this gas, which is at least seventeen times its natural quantity.
There are other agencies than carbonic acid gas which in civic life render the atmosphere impure. Of this nature is carbureted hydrogen gas, which is produced in various ways. This, says Dr. Comstock, is immediately destructive to animal life, and will not support combustion. It exists in stagnant water, especially in warm weather, and is generated by the decomposition of vegetable products. Dr. Arnott expresses the conviction that the immediate and chief cause of many of the diseases which impair the bodily and mental health of the people, and bring a considerable portion prematurely to the grave, is the poison of atmospheric impurity, arising from the accumulation in and around their dwellings of the decomposing remnants of the substances used for food and in their arts, and of the impurities given out from their own bodies. If you allow the sources of aërial impurity to exist in or around dwellings, he continues, you are poisoning the people; and while many die at early ages of fevers and other acute diseases, the remainder will have their health impaired and their lives shortened.
There are many instances on record where the progress of an epidemic has been speedily arrested by ventilation. A striking instance is given by the writer last quoted. "When I visited Glasgow with Mr. Chadwick," says he, "there was described to us one vast lodging-house, in connection with a manufactory there, in which formerly fever constantly prevailed, but where, by making an opening from the top of each room through a channel of communication to an air-pump common to all the channels, the disease had disappeared altogether. The supply of pure air obtained by that mode of ventilation was sufficient to dilute the cause of the disease, so that it became powerless."
Sulphureted hydrogen gas is also exceedingly poisonous to the lungs and to every part of the system. When pure, this gas is described as instantly fatal to animal life. Even when diluted with fifteen hundred times its bulk of air, it has been found so poisonous as to destroy a bird in a few seconds. "This gas," says Dr. Dunglison, in his Elements of Hygiene, "is extremely deleterious.[16] When respired in a pure state it kills instantly; and its deadly agency is rapidly exerted when put in contact with any of the tissues of the body, through which it penetrates with astonishing rapidity. Even when mixed with a portion of air, it has proved immediately destructive. Dr. Paris refers to the case of a chemist of his acquaintance, who was suddenly deprived of sense as he stood over a pneumatic trough in which he was collecting this gas. From the experiments of Dupuytren and Thenard, air that contains a thousandth part of sulphureted hydrogen kills birds immediately. A dog perished in air containing a hundredth part, and a horse in air containing a fiftieth part of it."
The preceding are far from being all the causes of atmospheric impurity. Besides these, there are numerous exhalations, as well as gases, that are poisonous. Some of these exhalations are more abundant in the night, and about the time of the morning and evening twilight. "Hence the importance," says a writer on health, "to those who are feeble, of avoiding the air at all hours except when the sun is considerably above the horizon."
Although the atmosphere, in its natural state, is not at all times perfectly pure, still it is comparatively so, and especially in the daytime. All, therefore, who would retain and improve their health, should inhale the open air as much as possible, even though they can not, like Franklin's Methusalem,[17] be always in it. This remark is applicable to both sexes, and to every age and condition of life.
The following, from the pen of an American author[18] who has written much and well on physical education, is pertinent to the subject under consideration: "We breathe bad air principally as the production of our own bodies. Here is the source of a large share of human wo; and to this point must his attention be particularly directed who would save himself from disease, and promote, in the highest possible degree, his health and longevity. We must avoid breathing over the carbonic acid gas contained in the tight or unventilated rooms in which we labor or remain for a long time, whether parlors, school-rooms, counting-rooms, bed-rooms, shops, or factories. The individual who lives most according to nature—who observes with most care the laws of life and health—must necessarily throw off much carbonic acid from his lungs, if not from his skin. It does not follow, however, that because this gas is formed we are obliged to inhale it. We may change our position, change our clothing, ventilate our rooms of all sorts, shake up our bed-clothing often and air our bed, and use clean, loose, and porous clothing by night and by day. We may thus very effectually guard against injuries from a very injurious agent.
"One thing should be remembered in connection with this subject which is truly encouraging. The more we accustom ourselves to pure air, the more easily will our lungs and nasal organs detect its presence. He who has redeemed his senses and restored his lungs to integrity, like him who has redeemed a conscience once deadened, is so alive to every bad impression made upon any of these, that he can often detect impurity around or within him, and thus learn to avoid it. It will scarcely be possible for such a person long to breathe bad air, or nauseous or unwholesome effluvia, without knowing it, and learning to avoid the causes which produce it. Such a person will not neglect long to remove the impurities which accumulate so readily on the surface of his body, or suffer himself to use food or drink which induces flatulence, and thus exposes either his intestines or his lungs, or the lungs of others, to that most extremely poisonous agent, sulphureted hydrogen gas. Nor will he be likely to permit the accumulation of filth, liquid or solid, around or in his dwelling. There are those whose senses will detect a very small quantity of stagnant water, or vinegar, or other liquids, or fruit, or changed food in the house, or even the presence of those semi-putrid substances, wine and cider. But some will indeed say that such integrity of the senses would be an annoyance rather than a blessing. On the same principle, however, would a high degree of conscientiousness in regard to right and wrong in moral conduct be a curse to us. If it be desirable to have our physical sense of right and wrong benumbed, it is so to have our moral sense benumbed also. Yet what person of sense ever complained of too tender a conscience, or too perfect a sense of right and wrong in morals?"