I’ve long relied on the three-beer rule for limiting my sun exposure during the summer, but a skin patch called SunSignals, which changes color when exposed to sunlight, showed that I could fry my epidermis faster than I could drink a single brew.
The thumb-sized, yellow adhesive patches are designed to turn dark orange when they have absorbed a certain amount of UVB light (the type of ultraviolet radiation that causes sunburn), telling wearers to get out of the sun, put on more clothing, or slather on more sunscreen. (The sensors are not meant to replace sunscreen.) With more than one million new cases of skin cancer diagnosed each year in the United States, the patches are a sensible reminder of our fragility.
Unfortunately, my patch changed color after only 17 minutes in the Los Angeles sun, barely enough time to finish a drink. My companions fared a little better, lasting 23 and 27 minutes before the sun-fear factor kicked in. While the kids in our group got a fun science lesson from the stickers, SunSignals seem more of a novelty than a technological breakthrough. It’s still up to sunbathers to decide whether they trust the sensors and want to keep reapplying sunscreen every 20 minutes. SunSignals are available in selected drug stores and supermarkets; a package of 18 can be bought online for $4.99.