cent. death occurs from asphyxiation.

The human body requires about three thousand cubic feet per hour, and
the great problem of ventilation is to give this amount of pure air,
moving, and with the proper amount of moisture.

It is a common belief that with each breath we take we are filling our
lungs with fresh air. This is not the case, for we never do get our
lungs filled with fresh air. What really happens is that we ventilate a
long tube which has no intercommunication whatever with the blood. Most
of the time our lungs are filled with impure air, and we simply exchange
a part of it for fresh air.


THE VALUE OF DEEP BREATHING

Deep breathing is undoubtedly extremely beneficial. Most of us, due
largely to the fact that Nature leaves a considerable margin of safety,
are able to carry on our ordinary activities without the requisite
ventilation of the lungs, especially if we do not exercise. This,
however, is injurious to the lungs, for it allows the blood to stagnate
in them. Exercise is Nature's method of compelling ventilation in the
lung area. Deep breathing may be used as a substitute, but the other
beneficial effects of exercise are lost.

The skin and the various glands connected with it form a complex
organism, the functions of which play a very important part in the work
which the body has to do. The skin aids the lungs in their work of
respiration; and, like the lungs, it throws off water and carbon dioxide
and absorbs oxygen. The respiratory work of the skin, however, is only a