To find the real value of ultraviolet glass and glass substitutes Dr. Janet Howell Clark, 39, associate professor of physiology at Johns Hopkins School of Hygiene & Public Health, measured light all last March, April and May. The discoveries, published last fortnight, were surprising:
The best ultraviolet glass, when a little old, lets only one third of the available ultraviolet sun rays pass through. (Manufacturers claim no more.)
The average amount of ultraviolet light in a 32-ft. room glazed with ultraviolet glass is only 1/600th of the noon-day's sun.
A person in such a...
To continue reading:
or
Log-In
