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The Secret of Everyday Things by  Jean Henri Fabre

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IMPURE AIR

[304]

"A
IR, on which our very existence from moment to moment depends, exposes us to serious dangers when it is vitiated with foreign emanations, with impurities, which, though perhaps harmless when inhaled in only a breath or two, are fraught with peril if their admission to the lungs continues. Breathing is never suspended, day or night, and anything that disturbs it even but slightly causes uneasiness at first and then, before long, grave danger. We are careful to have our food clean; we ought to be still more careful to have our air pure, its part in the maintenance of life being more important than even that of food. All air injurious to health from any cause whatsoever is called impure air.

"This impurity may be brought about in various ways, especially by the mixture of air with other gases, some of them dangerous merely in that they cannot take the place of oxygen in the combustion unceasingly going on in our bodies, others bringing peril with them in the form of poisons that infect the blood. Foremost among these latter is the carbonic oxide, or carbon monoxide, as it is also called, which all our devices for heating generate in greater or less quantity, and which is therefore a serious source of peril. This terrible gas is produced in our very homes.

[305] "Carbon can burn with two different degrees of completeness; that is, it can combine with a single or double portion of oxygen. Completely consumed, it gives carbonic acid gas, the gas produced by our breathing; half consumed it gives carbonic oxide. Let us turn our attention to the flame of a lighted candle. Just at the base of the flame we see a narrow band of beautiful blue. On the top of slowly burning coal may be seen little tongues of flame having the same blue color. That is the distinctive sign of the gas we are considering; those blue flames are produced by the complete combustion of carbon in the formation of carbonic acid gas. But before this final process the gas generated by the semi-combustion of carbon is as invisible and subtile as the air itself.

"Carbonic oxide is odorless, so that we remain unsuspicious of its presence, to our great peril. Inhaled even in a very small quantity, it poisons the blood, causing at first a violent headache with general discomfort, then vertigo, nausea, extreme weakness, and finally there may be a loss of consciousness. However short the duration of this state, life is imperilled. In my talk on combustion I warned you against this terrible gas, pointing out what precautions should be taken in respect to heating apparatus, the braziers used in laundry-work, and even our modest foot-stoves. All these, unless proper provision is made for the circulation of fresh air, expose us to serious danger. There is no need to dwell further on this subject; I have already said enough.

"Carbonic acid gas, which represents the final [306] stage in the combustion of carbon, is not a poison like carbonic oxide; our lungs always contain some of it, since it is in every breath we exhale; but, though it is not a poison, it is unbreathable, being by no means a substitute for the oxygen it has replaced in the composition of the air. Now, carbonic acid gas is produced in abundance all around us; in the first place, during every moment of our lives, by our own breathing; secondly, by the combustion that goes on in our heating appliances; thirdly, and less frequently, by fermentation.

"I shall not here take up again the subject of our ordinary means of heating and the dangers to our health that lurk therein and call for vigilant precautions on our part. It is a topic already sufficiently familiar to us. Let us say a few words about movable stoves.

"The ordinary stove has its undeniable merits. It is the best heating apparatus in respect to facility of installation, economy of fuel, and conservation of heat. But it is defective from the hygienic standpoint, especially in a small room occupied by many persons; it does not provide adequately for the renewal of the air, which it is capable of poisoning with its carbonic oxide.

"A form of stove that should be absolutely forbidden in our dwellings is the so-called American or movable stove, which is furnished all ready to be set up and is installed perhaps first in one room and then in another, without proper precautions as to its [307] adaptability to the apartment to be heated. By its mode of slow combustion it generates carbonic oxide in great quantities, and this may escape into the room at night and bring death to the sleepers. Too many accidents have already demonstrated the peril lurking in this form of heater.

"Fermentation, or the decomposition that goes on in the sweet juice of grapes in the process of turning to wine, produces carbonic acid gas in abundance. Hence it would be foolhardy unless assured beforehand of finding adequate ventilation, to make one's way into the vault or cellar where must is fermenting; and it would be still more foolhardy to descend into a wine-vat even after the wine itself has been drawn out. Carbonic acid gas may be there, forming a layer or stratum of some depth, since it naturally sinks to the bottom because of its being heavier than air. Hardly has the rash adventurer entered this layer, entirely undetected by the eye, when he falls unconscious, as if struck by lightning. Succor in this conjuncture is fraught with danger, and when it arrives it is often too late.

"The lesson is plain: the most elementary prudence calls for circumspection in entering any room or other enclosure where carbonic acid gas from fermenting wine may be present. Before entering there should always be a preliminary testing of the atmosphere. A lighted paper attached to the end of a long pole should be introduced into the wine-vat and into the remotest corners of the cellar. If the paper burns as usual, the atmosphere is free from danger; if it burns dimly, smokes, or, surest sign of all, goes [308] out altogether, carbonic acid gas is certainly present. Until ventilation has removed the danger let no one venture where the paper refuses to burn.

"Similar precautions should be taken in the case of recently opened crypts, deep excavations in abandoned quarries, and unused wells. Their atmosphere, often vitiated by carbonic acid gas, should first be tested with a lighted paper.

"After entering the lungs air gives up a part of its oxygen to the blood and receives in exchange an equal volume of carbonic acid gas produced by the combustion that takes place in the body. Hence the breath exhaled from the lungs is less vivifying than normal air. No argument is needed to prove that respiration cannot continue indefinitely in an atmosphere not subject to renewal. The ordinary proportion, twenty-one per cent, of oxygen in the air is never completely exhausted; but any considerable diminution, with the accompanying substitution of carbonic acid gas, is enough to render breathing difficult and, before long, dangerous. Placed under a bell-glass with no provision for renewing the air, any living creature will succumb in time, its duration depending on the rate of respiration.

"One word more: in its passage through the lungs the breath becomes laden with noxious emanations, the invisible refuse of the human organism in its unceasing process of destruction and reconstruction. Man's breath is pernicious to man. Air is vitiated by merely remaining in the lungs, where it loses a part of its vivifying element.

"For these various reasons it is important that [309] strict attention be paid to the renewal of the air in dwellings, especially in the rooms used for sleeping, these latter being usually small and almost always kept carefully closed for the sake of warmth and quiet. Alcoves and bed-curtains protect us, so that we are shut in with a limited supply of air which all night long undergoes no renewal, whereas in the other rooms of the house there is during the day a constant circulation of air through the frequent opening of windows and doors. When we awake in the morning the air about us cannot but be impure. Let us then open our bedroom windows as soon as possible and allow the pure outside air to flood the chamber and replace the unwholesome atmosphere formed during our sleep. Let us also admit the sunlight, another powerful vivifying agent, that it may penetrate with sanitary effect the depths of our alcoves and the darkness created by our drawn curtains.

"Under ordinary conditions air circulates about us in such abundance that we hardly have to pay any attention to its quantity; but this is not so in a closed room, a dormitory for instance, where a number of persons pass the night. Then it becomes necessary to provide a sufficiency of air for each one breathing within this limited space. Now, there passes through the lungs of every one of us about ten thousand liters of air per day, or four hundred and fifty per hour, which amounts to nearly four cubic meters for a night of eight hours. But since air is vitiated by respiration long before its oxygen is notably lessened in quantity, it is advisable to multiply this four by ten at least and to provide forty cubic meters [310] of space for each person occupying a sleeping-chamber in which the air, all night long, is not renewed. Indeed, if double this allowance is made, the demands of hygiene would be no more than satisfied.

"Eggs that are no longer fresh, and in which decomposition has begun, give out a noisome odor known well enough as the smell of rotten eggs. They tarnish any silverware that comes in contact with food containing them. These two effects proceed from the same cause, sulphureted hydrogen, a compound of sulphur and hydrogen. This gas is not only nauseating; it is also, a more serious matter, highly poisonous, being comparable with carbonic oxide in its harmful qualities. Whoever inhales it quickly succumbs.

"Now it so happens that sulphureted hydrogen is a constant product of the decomposition taking place in excrementitious matter, so that care is necessary that dwellings and especially sleeping-rooms be at a safe distance from all such sources of infection, and that any possible danger therefrom be counteracted by abundant ventilation.

"Nor is sulphureted hydrogen the only injurious product of decomposition. Everything that decays gives forth exhalations, whether malodorous or not, that cannot but injure our health. Therefore let us put a safe distance between our dwelling-houses and our stables, hen-coops, rabbit-hutches, dung-heaps, and other similar menaces to human welfare.

"In the country there is shown a somewhat excessive scorn of these dangers, but this carelessness is usually counterbalanced by plenty of ventilation. [311] Doors and windows imperfectly closed, badly fitting, gaping with cracks, and often wide open, allow free access of fresh air to every nook and corner. Nevertheless every deposit of refuse too near a well threatens the health of the whole household using that well."


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