KEEPING WELL 405
lungs is stimulated, and the faster we breathe. In cities where the air is loaded with the smoke from factories, the gases from the breaking up of various chemicals, the carbonic acid gas from the exhalation from the lungs of countless men and animals, and the effluvia from decomposing animal and vegetable waste material, it is far less wholesome than in the country where vast areas of open space permit the free movements of atmospheric currents, where the vegetation is constantly yielding oxygen and absorbing carbonic acid, and where the number of men and animals which are drawing upon the supply is far too small to make the slightest effect upon the total volume which is drawn upon, or to interfere with its purity. Unless a house or other enclosure which is occupied by men or animals is in free communication with the external air, it is far less capable of sustaining life than the external air.
In winter, many houses have a totally inadequate air supply. They are overheated from stoves or furnaces, windows are sealed, the burning of lamps, candles, and illuminating gas consumes much oxygen, and the air supply is further contaminated by the escape of deadly coal gas and the carbonic dioxide which is exhaled from the lungs of their occupants. It is not strange that for this reason much more sickness prevails in winter than in summer, and that too in a season when the cold, external air is more stimulating and bracing than at any other time in the year. There is little doubt that a large proportion of the disease which prevails during the winter season could be entirely avoided, if greater wisdom were shown in admitting to our houses a sufficient volume of pure air, the freest and most abundant of all the gifts of nature.
Air in motion is much more salubrious than air which is stagnant. We realize this in the sultry days of summer when a cool breeze or the brisk action of a fan gives an agreeable change to our feelings. We realize it too after reaching the top of a hill or mountain where we are at once exhilarated and revived by the wind and the lighter atmosphere. Moving air, even when it contains impurities, has less chance of doing harm than stagnant air.