The prospect of skin cancer from exposure to the Sun can bring anxiety to what should be a pleasant time out on the beach, especially for parents with kids. 
Because there’s no convenient way for the general public to actually measure UV exposure, people end up using rules of thumb, estimating things, and setting timers that don’t reflect actual danger from the hydrogen fusion ball over our heads.
A new wristband developed at the University of Strathclyde in Glasgow, Scotland and commercialized into a product by Swedish company Intellego Technologies, should be available next spring to take the guesswork out of gauging exposure and help end arguments with kids at the beach. When the wristband turns pink, they go under the umbrella.
The wristband relies on a compound that releases acid when exposed to ultraviolet light. A dye that responds to the pH level of its environment changes color as more acid is added. The change between the yellow color the wristband starts with and pink, the top of the range the dosimeter measures, provides a quick and easy gauge of one’s exposure.
University of Strathclyde press release: Sun monitor set to go on the market…