THE TRUTH ABOUT SUNSCREENS, SPF'S, AND SUNBURNS
What Does SPF Mean?
SPF stands for sun protection factor. Some people like to call it sunburn protection factor.
The Good Side
Waterproof sunscreen is actually water resistant. There's no need to reapply it every half hour.
There is no need to buy any sunscreen with an SPF of 50 or higher. SPF 30 blocks 97 percent of the rays and SPF 50 blocks 98-99 percent of the rays, so there is very little difference. You're paying more for something that will protect you almost the same. Anything higher then SPF 50 is working the same as the SPF 50.
Reapply sunscreen every two hours normally works best to ensure full coverage.
If you have an SPF 15 on, that means that you can be in the sun for 15 minutes before the sunscreen starts to wear off.
The Bad Side
Zinc oxide a chemical in most sunscreens could react with sunlight and create a chemical reaction that releases free radicals – molecules that are often attributed to causing cancer.