DUST AND DUSTING Dust is defined by the Century Dictionary as " earth or other matter in fine dry particles so attenuated that they can be raised and carried by the wind." The particles of earth and other mineral substances con tained in dust are troublesome, but not especially harmful. In addition to this, dust contains three sorts of spores or germs, i. e., molds, yeasts, and bacteria. All of these are alive, or capable of life, and under suitable conditions multiply rapidly. They are invisible except under the micro scope, and are exceedingly numerous. The conditions most favorable to their growth are darkness, warmth, and moisture. Direct sunlight kills them, and in the absence of moisture, they do not usually multiply.
All of these germs produce minute plant or vegetable organisms of which common mold or " mildew " and the yeast used in raising bread are familiar examples. A visible il lustration of the spores or germs, that are the seeds of plants of this sort, is found in the common puff ball or " smoke " ball, so familiar to country children. When broken, the contents escape as a cloud of dust.
These are the spores or seeds of the plant. The air is full of similar spores or germs, and while many of these are not harmful, others are the agents of decay and a few are the germs of contagious diseases. These are called bacteria. Their natural home is in moist soil. Thus they multiply rapidly in the soil of damp cellar floors, especially if decaying vegetable matter is present, and in the accumulation of dirt and grease beneath boarded-up sinks, and in the corners of rooms that are shut up and darkened. They are also very numerous about drains and cess pools. They sometimes find their way into the body by means of drinking water or by accidental contact with the body when the skin is cut or scratched. But more frequently they are dislodged from some moist local ity and become dry. Then they are caught up by every passing breeze, and float in the air as dust, whence they are taken into the mouth and lungs in breathing.
The bacteria which cause disease find lodgment under certain condi tions and grow in the body. They
throw off in' the process of growth certain poisonous substances called toxins. And these toxins are what produce the symptoms and condi tions present in such diseases, and eventually, in many cases, produce death.
Spores or germs of mold that set tle on carpets or other fabrics and on wood, books, or other objects where moisture is present, produce a crop of tiny plants, well known under the name of mildew. The yeast germs are less common and are relatively harmless. Knowledge of these facts emphasizes the dangers of dust, which may be avoided in three ways: by sterilization, by prevention, and by removal.
Sterilization of Dust.—The most efficient agent to sterilize dust, by killing germs that it contains, is di rect sunlight. Like many other things that are plentiful and free, sunlight is not appreciated at its true value. In cities, buildings are crowd ed so closely together as to shade one another, and in the country too frequently direct sunshine is cut off from dwelling houses by thick masses of evergreen and other trees, shrubs or vines. Formerly it was the custom in many localities to keep the parlor and spare chambers closed by shut doors and drawn blinds. And rooms are still too often darkened to pre vent carpets and other fabrics from fading. Happily, a change for the better is already apparent. Hard wood floors and Oriental rugs do not fade. It is much less customary than formerly to exclude light and air from spare rooms, to board up sinks and other plumbing, and otherwise to harbor breeding places for the germs of mildew, disease, and decay. In cities, boards of health are con stantly studying these matters, and laws have been passed that tend to prevent unsanitary conditions. The resulting knowledge is being rapidly spread everywhere. And within re cent years the death rate of most lo calities has been greatly diminished. There is little doubt that many deaths have been due to conditions that could have been prevented by a, knowledge of the dust dangers.