What do the letters SPF on a bottle of sunscreen stand for?
A) Silly pool fun
B) Super powerful forehead
C) Sun protection factor
C is the correct answer. But did you know you should put on sunscreen before and after silly pool fun? From the top of your super powerful forehead down to your uncovered toes?
Sunscreen protects you from ultraviolet radiation emitted by our local star. UV light can damage skin cells, causing sunburn, age spots, wrinkles and skin cancer. All sunscreens have an SPF on their labels, telling you its ability to screen or block out the sun's UVB rays. For example, sunscreen with SPF 30 blocks 97 percent of UVB rays.
There are tons of different brands of sunscreens. The important thing is to use broad-spectrum sunscreen. That means it protects against both UVA and UVB rays. Some types of sunscreen contain chemical UV filters and some use physical UV filters. Some have a combination of both.
Chemical UV filters work by absorbing UV light and converting it into heat. According to Britannica Library, two molecules often found in sunscreen are octinoxate (absorbs UVA rays) and avobenzone (absorbs UVB). When light hits these molecules, their electrons get excited. Then the electrons go back to their original energy levels, giving off a small amount of heat in the process.
Sunscreens with physical UV filters often contain zinc oxide or titanium dioxide. These are mineral compounds that form a barrier on your skin. They scatter and reflect UV rays.
Health Canada and the Canadian Cancer Society recommend that you reapply sunscreen at least every two hours. Or more often if you're swimming (or sweating) a lot! And remember: even if you can't see the sun, UV rays can still pass through the clouds. Stay sun smart, no matter the season or weather!
Related wonders:
Is there a dark side of the sun?
Why do we get wrinkles?
