Abstract
PHYSIOLOGICAL research has proved that the cause of discomfort felt in close, ill-ventilated rooms is due to the physical, and not to the chemical, properties of the atmosphere. We exclude gross contamination by products of imperfectly combusted coal gas, e.g. from defective gas fires imperfectly liued. These chemical products irritate the nose and throat, and one of them—carbon monoxide—is a poison. We exclude too, those mines and factories wherein certain poisonous products of industry may pollute the atmosphere. We are writing of rooms crowded with human beings, of over-heated, windless rooms. The percentage of oxygen in such crowded rooms is never reduced by more than 1·0 per cent., and at any of the mountain health resorts the concentration of oxygen is reduced considerably more owing to the attenuity of the air. Similarly the percentage of carbonic acid is never raised in crowded rooms to such a level that it has the least toxic effect. Within the lungs a constant concentration of carbonic acid of about 5 per cent, of an atmosphere is maintained. The acidity of the blood regulates the action of the breathing mechanism, so that both it and the concentration of carbonic acid in the lung are kept constant. The only result of breathing an atmosphere containing 0·5-1·0 per cent, of carbonic acid—the most crowded room does not contain more—is a slight deepening of the respiration by which the concentration in the lung is kept at the normal figure. It becomes difficult to maintain the normal concentration in the lung when the concentration in the atmosphere rises above 3·0 per cent.; the breathing of even a resting man then becomes over-laboured. The crew of a submerged submarine feels the need for fresh air when the CO2 concentration rises above this level.
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HILL, L. Healthy Atmospheres . Nature 95, 205–207 (1915). https://doi.org/10.1038/095205a0
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DOI: https://doi.org/10.1038/095205a0