RELATION OF THE ALTITUDE OF THE SUN TO ITS ANTIRACHITIC EFFECT
- 16 March 1929
- journal article
- research article
- Published by American Medical Association (AMA) in JAMA
- Vol. 92 (11) , 860-864
- https://doi.org/10.1001/jama.1929.02700370008002
Abstract
Exposure of the body to sunshine is now universally accepted as the most effective means for the prevention and cure of rickets. Solar radiation which reaches the earth's surface is composed of invisible heat rays which have wavelengths longer than 760 millimicrons (a millimicron is one millionth millimeter), visible light which varies in length from 760 to 380 millimicrons, and invisible ultraviolet rays which range from 380 to 290 millimicrons. Rickets is prevented and cured by exposure to ultraviolet rays not longer than 302 or possibly 313 millimicrons.1 Rays longer than 320 millimicrons certainly do not produce any discernible effect.2 As the shortest rays in sunshine are 290 millimicrons, and the longest ones effective in the prevention and cure of rickets 302 or 313 millimicrons, it is evident that the effective solar rays are limited to a very narrow zone of the shortest ultraviolet rays present in sunshine.This publication has 0 references indexed in Scilit: