186 



SCIENCE 



[N. S. Vol. XLIV. No. 1128 



relation of atmospheric conditions to blood 

 pressure I must leave until the abundant 

 data that have been accumulated by the 

 New York Commission have been subjected 

 to a more careful examination than has yet 

 been possible, although it may be said that 

 excessively high temperatures and high 

 humidities are accompanied by an eleva- 

 tion of both systolic and diastolic pres- 

 sures. A study of the commission's records 

 by one of the various methods for evalu- 

 ating vascular data seems to reveal an- 

 other fact of distinct importance. When 

 the human body rises from a recumbent to 

 a vertical position the threatened settling 

 of the blood into the lower parts by gravity, 

 with the resultant deleterious effects, ought 

 obviously to be counteracted. In the 

 healthy person the most expedient way to 

 accomplish this is by means of a vigorous 

 vasomotor mechanism acting to constrict 

 the arterioles and raise the blood pressure. 

 This mechanism is assisted by a quickening 

 of the rate of the heart's beat. If the mech- 

 anism be enfeebled from any cause, there 

 may be, along with the change of posture, a 

 lessened rise of blood pressure, or even a 

 fall, and a great increase in the heart rate. 

 A comparison, therefore, of the change in 

 the systolic blood pressure and the change 

 in the rate of the pulse resulting from a 

 change of the position of the body from the 

 horizontal to the vertical gives a clue to the 

 efficiency of the vasomotor mechanism. On 

 this basis Crampton 5 has constructed a 

 scale of percentages of vasotone. In terms 

 of this scale the New York Commission 

 finds that the vasotone diminishes in hot and 

 humid air, and increases as the air becomes 

 cooler and dryer. Thus these results indi- 

 cate that a distinct vascular benefit follows 

 from exposing the body to a cool dry air. 

 Atmospheric conditions exert on the 



5 Crampton, New York Med. Jour., 98, 916, 

 1913. 



respiratory system effects of various kinds. 

 On the rate of respiration a moderate degree 

 of heat and humidity seems to be without 

 effect, but more extreme conditions cause a 

 quickening of the breathing, and this is 

 probably accompanied by more shallow 

 respirations. The more extreme conditions 

 too appear to result in a lowered concentra- 

 tion of carbon dioxide in the air of the pul- 

 monary alveoli, although I can not yet 

 quote actual figures to demonstrate this: 

 The matter, however, is important, since a 

 lowered alveolar carbon dioxide may signify 

 an increased content of hydrogen ions, in 

 other words increased acidity, in the blood. 

 Eastman and I are now investigating this 

 point with much interest. 



The mucous membrane of the respiratory 

 tract is markedly affected by atmospheric 

 conditions. This was shown three years 

 ago by Hill and Meucke, 6 and it has re- 

 cently been quite fully investigated by 

 Miller and Cocks 7 under the auspices of the 

 New York Commission. Exposure to heat 

 causes increased swelling, redness and secre- 

 tion in the nasal mucosa, and these effects 

 are more marked when the humidity of the 

 air is high. Exposure to cold reverses the 

 effects. When the subject passes from a 

 cool to a hot room and a current of air is 

 played upon the face there occurs a diminu- 

 tion of the swelling and the secretion ; but 

 passage from a hot to a cool room with a 

 similar draught results in increased swell- 

 ing and increased secretion. This latter 

 condition seems to be especially favorable 

 for the development of infectious micro- 

 organisms. But the causative relation of 

 the bacteria of the nasal mucosa to "colds" 

 seems to be still in doubt. 



The distaste for physical labor which we 

 feel on a hot humid day is a common expert- 

 's Hill and Meucke, Lancet, 1291, 1913. 

 7 Miller and Cocks, Trans. Am. Climatol. and 

 Clin. Assoc, 1915. 



