HOW TO CALCULATE ROOM VENTILATION
Dr. Kellogg has supplied some exceedingly useful calculations of the degree of ventilation needed in rooms of various sizes. “Every one,” he says, “should become intelligent in relation to the matter of ventilation, and should appreciate its importance. Vast and sometimes irreparable injury frequently results from the confinement of several scores or hundreds of people in a school room, church or lecture room, without adequate means of removing the impurities thrown off from their lungs and bodies. The same air being breathed over and over becomes intensely charged with poisons which render the blood impure, lessen resistance and induce susceptibility to taking cold and to infection with germs of pneumonia, consumption and other infectious diseases which are always present in a very crowded audience room.
“Suppose, for example, a thousand persons are seated in a room forty feet in width, sixty in length, and fifteen in height; how long a time would elapse before the air of such a room would become unfit for further respiration? Remembering that each person spoils one foot of air every second, it is clear that one thousand cubic feet of air will be contaminated for every second that the room is occupied. To ascertain the number of seconds which would elapse before the entire air contained in the room will be contaminated, so that it is unfit for further breathing, we have only to divide the cubic contents of the room by one thousand. Multiplying, we have 60 × 40 × 15 equals 36,000, the number of cubic feet. This, divided by one thousand, gives thirty-six as the number of seconds. Thus it appears that with closed doors and windows breath poisoning of the audience would begin at the end of thirty-six seconds, or less than one minute. The condition of the air in such a room at the end of an hour cannot be adequately pictured in words, and yet hundreds of audiences are daily subjected to just such inhumane treatment through the ignorance or stupidity of architects, or the carelessness of janitors, or the criminal negligence of both.”