OUTDOOR AND INDOOR AIR In frosty weather the air we exhale is visible, as a white cloud of vapor. In warm weather, the exhaled air, though invisible, contains numerous liquid particles and diverse organic and inorganic products of gas exchange. A single exhalation whose volume is approximately 500 contains 200 million particles, 75% of which are charged. During eight hours of sleep, one person exhales about two trillion particles into the bedroom air. The mass of exhaled particles rapidly disperses, and by diffusion, gradually fills the entire room, literally polluting its air. Some of the exhaled particles combine chemically with the oxygen in the air, thereby "spoiling" it. As a result of their minute size, these particles settle very slowly, and take part in thermal motion.
Measurements and calculations have shown that one person can rapidly pollute the air, even in a large room, with his respiratory wastes, and consequently he soon begins to inhale his own wastes. If water is mechanically sprayed in an inhabited room (with an atomizer), the respi ratory-waste particles settle on the droplets, converting the charged particles of the sprayed water into charged aerosols which are detrimental to health. This phenomenon, experimentally confirmed (1933-1934), re
quires a very cautious attitude toward the so-called "hydroionizers," which atomize charged water mists without ionizing the oxygen of the air.
Different processes occur when water is mechanically dispersed out doors, such as in the sea by the surf, or during heavy rains, at high water falls, and near rapid mountain streams. In the natural environment, the air oxygen may condense on the surface of charged water particles, and with sufficient kinetic energy the oxygen molecules acquire a negative charge, thereby becoming true air-ion aggregates, or "heavy" air ions.
In addition to its intrinsic salubrious properties (due to its ionic con tent), fresh outdoor air is also healthy because a man breathing such air does not inhale his own respiratory wastes, as he must do indoors. This fact is of great importance, and must be considered when examining the conditions of the "indoor" air breathed by people in enclosed premises. The builders of our houses must bear this in mind, and should therefore provide for air ionization throughout the building; this target can be achiev ed within this decade.