yficrioN III., 1906. [ 203 ] Trans. R. S. C. 



XIII. — Deficient Humiditif of the Atmosphere. 

 By T. A. Starkey, M.B., D.P.H., F.E.S.I., Professor of Hygiene 



AND 



H. T. Barxes, D.Sc, F.R.S.C, Associate Professor of Physics, McGill 

 University, Montreal. 



Reax:! May L'3rd, 1906. 



The importance of the intiuence of a dry atmosphere on the hu- • 

 man organism lias been in a great measure overlooked. The question 

 is one uf great moment in Canada, especially in those parts where, during 

 the colder months, the heating of the houses necessitates the heating of 

 the indoor atmosphere, thereby causing a tremendous drying of the air, 

 or in other words, a lowering of the Relative Humidity. 



This excessive dryness is common knowledge, and most householders 

 are full}- acquainted with the ravages it creates amongst their house- 

 hold effects, particularly woodwork, ivory pieces, etc. How many at- 

 tempts on the part of the householders has one witnessed, to increase 

 the moisture necessary in the air — hanging cans containing water on the 

 heating coils — placing bowls of water in each room, etc., etc. But all 

 these attempts were made with a view simply to preserving the furniture, 

 ornaments, etc., and never to benefit the health of the inmates. 



The results of these homely makeshifts were always disappointing, 

 because the amount of water which could be evaporated under such con- 

 ditions as above described, did not sensibly affect the humidity condi- 

 tions — as will be shown later, several gallons per day in an ordinary 

 sized house are required to even bring the relative humidity to 50 per 

 cent. 



The action of a dry atmosphere on the human organism is a direct 

 one. It affects primarily the mucous membranes lining the respiratory- 

 tract — chiefly that of the nose, the throat and the bronchial tubes. It 

 is a purely mechanical irritant, resulting in a condition of congestion of 

 the mucous membranes before mentioned. If this irritation be con- 

 tinued for any length of time the swollen mucous membranes with diffi- 

 culty regain their normal state, and in this connection it may be 

 pointed out that different individuals will suffer to different degrees, 

 according to their personal factor or idiosyncrasy — there are some 

 people whose mucous membranes are " weak " and will quickly react to 

 this irritation; finally, what is more important in these cases, the mucous 

 membranes do not recover their normal tone, or only with very great diffi- 

 culty after a long time. 



