Remember the ABCs of sun protection before you head outside this summer

SPF. UVA. UVB. It’s enough to make your head spin. But these letters are crucial to keeping your skin healthy and sunburn-free this summer.

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Before you hit the pool or beach, be sure to brush up on the basics of sun protection.

UVA & UVB

Ultraviolet A rays are the ones that age you. Ultraviolet B rays are the ones that cause sunburn. Both have been linked to skin cancer. Learn more about this at skincancer.org.

Tip: Don't be fooled by sunscreens that claim to be waterproof and sweatproof. There's no such thing, as water is notorious for washing the protection away. Nowadays, most sunblocks will tell you how long they are water resistant, which is more accurate.

SPF

A sunscreen's sun protection factor is its most important number. The FDA recommends only buying sunblock with an SPF of at least 15.

But take note: According to Steven Wang, director of dermatologic surgery and dermatology at Memorial Sloan-Kettering Cancer Center, SPF refers mainly to the amount of UVB protection a sunscreen offers -- not so much UVA protection.

Sunscreen with an SPF greater than 50 isn’t significantly more effective at preventing sunburn, so it’s not necessarily better to go higher than 50. SPF 50 blocks an estimated 98 percent of UVB rays.

Tip: Be sure to buy sunblocks that say "broad spectrum" on the label. Those are the only ones that protect you from all the sun's harmful rays.

When and how should you use sunblock?

Did you know that 80 percent of ultraviolet rays still manage to get through cloud cover? Therefore, you should always wear sunblock, even on overcast days, if you plan to spend time outside. The same goes for road trips, as harmful rays can also reach your skin through window and windshield glass.

It takes one ounce of sunscreen to cover the average adult's entire body. An ounce is about enough to fill a shot glass. Sunblock should be reapplied every two hours, even if you aren't swimming.

Cox Media Group