Why is it that, as a rule, people who live in the country are healthier and live longer than those who live in towns? There are many reasons, but one certainly is that they live more in the open air. The town-dweller lives a largely indoor life, shut up in small, ill-ventilated rooms, or in crowded theatres, picture-houses, or lecture halls; and even when he is outside in the streets, the air he breathes is more or less contaminated by smoke and dust and other impurities.
Everyone knows that air is essential to life, and that if we are prevented from breathing for even a few minutes, we shall die; but everyone does not realize that the breathing of impure air is almost as bad as not breathing any air at all, for impure air slowly poisons the whole system.
Air is composed of two gases, oxygen, and hydrogen, and it is the oxygen we take into our lungs with every breath that is so essential to life. The red blood which the heart pumps through arteries to every part of the body comes back to the lungs by the veins as purple blood loaded with impurities, and especially with a gas which is poisonous to life. In the lungs, it meets the oxygen breathed in from the outer air, and the oxygen purifies and revitalizes the blood, which passes on to that heart to be pumped round the body once more on its life-sustaining mission. The poison gas, called carbonic acid gas, which the venous blood unloads in the lungs, is breathed out into the air and is thus got rid of with every breath.
Now we can understand the double evil of breathing for any length of time the air of a closed up and crowded room. First, we gradually exhaust the oxygen in the limited amount of air we breathe, until we are not getting sufficient oxygen to purify and revitalize the circulating blood. Secondly, we are filling the air of the room at every breath we breathe out with that poisonous carbonic acid gas, and this gas we take in again into our lungs with every inspiration. The result is that the circulating blood becomes loaded with poison, which gradually reaches and poisons the whole system. The first effects of this poison are sleepiness, headache, and lassitude, which will pass off as soon as we get into the open air. But people who habitually live in stuffy, unventilated rooms and an impure atmosphere, eventually become liable to all kinds of diseases arising from poisoned blood and deranged lungs.
We can now understand the importance of ventilation. The windows and ventilators of the rooms we live in must be kept open, so that a current of pure air will always be passing through, driving the stale, used-up air out, and replacing it with clean air full of oxygen. It is especially important that bedrooms should be kept well-ventilated at night, for to sleep in a shut-up room is simply to be slowly poisoned. And the more we can spend our time right out in the open air, the better it will be for our health. The dreaded disease called consumption of the lungs is largely the result of constantly breathing bad air, and the open-air treatment is the only real cure for it.