No one can live without air as one can without water for a few days and without food much longer. Therefore, nature has surrounded us with air on all sides so that we can get it without any effort.
We take in air through our nose into our lungs. The lungs act as a sort of bellows. The atmospheric air which we breath in has a life-giving substance- a gas known as oxygen. The air that we breath out contains poisonous gases. These can kill us if they are not immediately allowed to spread out and get diluted by the atmospheric air. Hence the necessity of proper ventilation.
The air comes into close contacts with blood in the lungs and purifies it. Many people do not know the act of breathing. This defect prevents an adequate purification of their blood. Some people breath through their mouth instead of their nose. This is a bad habit. Nature has so designed the nose that it acts as a sort of filter for the ingoing air and also warms it. In mouth breathers the atmospheric air reaches the lungs without the preliminary filtration or warming. It follows therefore that those who do not know how to breathe should take breathing exercises. They are as easy to learn as are useful. I do not wish to go into a discussion of the various asanas or postures. I do not mean to say that these are not important or useful. Bu I do wish to emphasize that a well-regulated life outweighs the advantage of studying elaborate postures that ensure breathing through the nose and free chest expansion is enough for our purposes.
If we keep the mouth tightly close, the breathing would have to be carried out by the nose. Just as we wash our mouth every morning, the nose should be also be cleaned. Clean water, cold or Lukewarm water is the best agent for this purpose. It should be taken in a cup in the palm of the hand and draw up through the nostrils. It is possible to draw the water up through one nostril, the other remains closed, and expel in through the other by opening it and closing the former. The process should be carried out gently so as to avoid discomfort. In order to cleanse the back portion of the nose known as nasopharynx, water should be brought out by the mouth or even swallowed.
We must see that the air that we breath in is fresh. It is good to cultivate a habit of sleeping in the open under the star. The fear of catching a chill could be dismissed from the mind. Cold can be kept out by plenty of covering. This covering should not extend beyond the neck. If cold is felt on the head, it can be covered with separate piece of cloth. The opening of the respiratory passage - the nose - should never be covered up.
The day clothes should be changed for loose night clothes before retiring. As a matter of fact no clothes are necessary at night when one sleeps covered with a sheet. Tight-fitting clothes should be avoided even during day.
The atmospheric air around us is not always pure, neither it is the same in every country. The choice of the country does not always lie in our hands but the choice of a suitable house in a suitable locality does rest with us till some extent. The general rule should be to live in a locality which is not too congested and insist upon the house being well lighted and well-ventilated.