The Hygiene of Ventilation and Heating
In regard to ventilation and heating the situation is much the same as with lighting. Until recently all public buildings were without special provisions for ventilation, it being assumed that enough air would come in through doors and windows. The private dwelling was the model followed in this matter. A dwelling occupied by a few people leaks enough fresh air so that even when all the windows are closed the air is tolerable. When fifty or a hundred people in a public building are crowded into a space that is proportionately much smaller than the space in a dwelling and when, furthermore, through improvements in methods of construction the leakage of fresh air is almost entirely stopped, the situation calls for artificial means of introducing air and distributing it. The situation with regard to fresh air is complicated in all colder climates by the necessity of producing and conserving artificial heat. Modern heating arrangements are capable of maintaining large buildings at a summer temperature even in the coldest weather, but in order to do this at reasonable cost the building must be made as nearly air-tight as possible. The temperatures secured through artificial-heating plants have also brought another evil. The air raised to a high temperature is abnormal in humidity because it is taken from outdoors, where it is cold and the humidity is low, and is raised by heating to a condition where it can absorb a great quantity of moisture. Such air is very dry and takes moisture in an excessive degree from the moist linings of the human respiratory tracts and thus irritates and fatigues the people exposed to the dry air, becoming a serious menace to comfort and even to health. To meet these difficulties it has been necessary to introduce into all public buildings artificial ventilating and humidifying systems. Even in one-room rural schools, where the simpler types of architecture must still be adhered to, it is common, as pointed out above, to jacket the stove, thus making it possible to circulate fresh air and to introduce an evaporation reservoir which will render the humidity more nearly normal. Above all it is important that teachers understand that these matters cannot be left to mere chance. Life indoors is artificial at best, and its conditions must be guarded as carefully as possible.