TESTS OF VENTILATING PLANTS
Journal of the American Medical Association
The proper tests of any ventilating system designed for serving rooms of human occupancy depend ultimately on biologic facts. What qualities of the atmosphere are most conducive to the economy of the human organism? What are the ordinary variations from the ideal atmosphere and how does the organism react? When the engineer designs a structure, he must know the forces that will tend to destroy or strain it, he must know their direction and intensity and he must know from tests the strength of
... s the strength of the material which is to withstand the forces. In the problem of ventilation we assume and, without doubt, correctly assume that the open air of the countryside or of the sea is the normal, most beneficial atmosphere. We know something of its characteristics in a chemical, electrical and physical sense, and we know somewhat less of the variations from the ideal atmosphere in so far as they are significant from the standpoint of the problem of ventilation. When we attempt to study the structure, the human body, and the effects on it of varying conditions of atmosphere, we naturally find the problem of a most complex nature. I have been trying to study the ven¬ tilating problem from this standpoint during a part of the last year. It is a difficult thing for one with only a meager training in biology to attempt, but as a result of the trial, I am convinced that the ventilating engi¬ neer, in order to understand the principles underlying his work, must go beyond the mere mechanics of materials involved, and must have an appreciation of the relative biologic values which are fundamental. In a very recent published article by one of the best known hospital architects of this country, I find the following statesment: "Without -doubt, this unknown constituent which gives the obnoxious odor or smell to bad air, such as is evident in assemblies, most notice¬ able in warm rooms as in our nickel theaters, is a harmful factor." Also in the same article : "Let me impress upon you that dirty air kills more people than dirty water, dirty milk, and dirty food combined." In the discussion which followed, a prominent member of the Chicago Ventilation Commission emphasized the importance of the danger of infection from air. The general impression that the acute communicable diseases can be greatly lessened by improved means of ventilation either by eliminating direct infection or by providing air in superlative quantity, distribution, and quality, is one which seems to me to be erroneous. Direct contact, mouth spray, uncleanly personal habits, are without doubt the most fruitful causes of these dis¬ eases. Resistance to infection is perhaps both general and specific. Specific resistance may be in some cases artificially produced, but as far as my observation goes, our knowledge of immunity is comparatively small. That there is such a thing as general resistance, often spoken of by the layman as vitality, that may be reduced by unfavorable e_: dronment, is also probably true.