The SPF – or “sun protection factor” – number on a sunscreen’s label is a guide to the product’s level of sunburn protection.
In general, the SPF number indicates how much longer you can stay exposed to the sun before getting sunburned when wearing sunscreen, as opposed to without sunscreen.
For example, it takes 15 times longer to burn with sunscreen SPF 15 than without sunscreen. However, despite the SPF number, sunscreen should be reapplied at least every 2 hours.
UV rays are usually strongest from 10 a.m. to 2 p.m., but remember, the longer you are out in the sun, the more exposed you are to UV rays!
The sun's UV rays are strongest during the summer months, but UV rays reach the Earth every day, year-round, even in winter!
Surfaces like concrete, sand water and snow can reflect 85% of the sun's rays back at you.
UV rays are strongest as you near the Equator, and the higher the elevation, the greater your exposure.
If you have fair skin, as well as light-colored eyes and hair, you're likely to burn more easily when exposed to UV rays.