There were some warnings last summer about the people who like to lie out in the sun on the beaches, to the effect that it was possible that certain skin cancers might develop from too much of such exposure.
It is to be hoped that this will not be taken too seriously. Certainly it applies only to elderly people, and certainly it applies only to the summer. Children will not develop cancer of the skin, or at least so rarely as to make the thing negligible, and children and expectant mothers need a good deal of sunshine. This warning is especially applicable to the winter season, when the short gray days are likely to cut down the total amount of sunshine, and the inclement weather tends to keep people indoors.
It should be remembered that ordinary window glass shuts out the particular light wave in sunshine which is valuable, and it is interesting to note that cellophane allows it to come through. The only substitute for window glass which we have hitherto had, which was known to allow the ultra-violet rays to come through, was quartz glass, which is quite expensive, until this discovery of cellophane’s property in that respect.
We are assured by a member of the faculty of Johns Hopkins university that cellophane actually has this property. He writes: “Cellophane cuts down somewhat the intensity of sunlight without affecting the short wave length limit of the transmitted radiation, therefore, a slightly longer exposure through cellophane will accomplish much the same thing as direct exposure to sunlight.”
For those who want to take some sun baths during the winter this is important, and a window frame made of this substance can be constructed so that the child or expectant mother can receive sunlight exposure over a large area of skin surface, at the same time staying indoors where it is warm, and thus avoiding the danger of chill and exposure.