The danger of the close room should be brought home to all, even children, through instruction in hygiene in the public schools; and even from their very youngest days this should be instilled into the minds of youth, together with the contra-advantages of fresh air. By these means they will be accustomed to the fresh air and its beneficial effects, as much as they will learn to detest the horrors of the air exhaled by other people, which is the source of so many infections. Every one who wishes to enjoy life during youth, and live to a good old age, should abominate a close room and never, if he can possibly help it, pass an hour in such an atmosphere. ------------------------------------------------------------------------ CHAPTER XXXIII. HYGIENE OF ARTIFICIAL HEATING—THE DANGERS OF HEAT BY STEAM AND A FEW HINTS ABOUT THEIR PREVENTION. OLD people are particularly sensitive to cold, and they therefore need a warm room when the temperature falls in the autumn. In old age, especially in its advanced stage, the processes of oxidation are diminished, and thus less natural warmth is produced; but, as we give off more heat in cold weather, it is only natural that they will feel the cold then much more than younger individuals. The rooms, therefore, in which old people live must be kept very warm, in the same manner as we do with infants, especially for those who come of parents with degenerated thyroids. Thus we see again how old age and infancy present many parallel features. But, if a very warm room be compulsory for aged folks, no such necessity exists in the case of the young or middle aged, and it is abusing their health if they remain long in rooms heated above 75° to 85°, or sometimes 90°, where, at the same time, every window is sedulously closed on all sides, so that no fresh air can find entrance. Such overheated rooms we usually find in northern climates, and the air in such cases is frequently hotter in the house in winter than we find it in the open on a comfortably warm summer day, when, being in the open, the heat can certainly be better borne than in a close room. In America many things are better than in Europe; but this certainly does not apply to the method of heating used in the majority of the houses, hotels, and office buildings, all of which are mostly overheated, and that by steam heat, and very frequently with defective ventilation, if there be any at all. The worst part of it is that a uniform heat is maintained, whether it be a warm or a cold day; thus, the air temperature was 55° F. on October 15, 1906, when I was in New York, and in one of the most fashionable hotels the temperature was 75° F. In Houston, Texas, there was a heat wave in February, 1907, with disagreeable hot weather, yet 70° F. of steam-generated heat was maintained in the hotels, which made life unbearable for those who, like the author of this book, are so fond of fresh air.