woman applying sunscreen

Each year, more Americans are diagnosed with melanoma, the deadliest form of skin cancer.

According to the National Cancer Institute, the rate of new melanoma cases among American adults has tripled since the 1970s.

With these rising numbers, experts say it’s extremely important to wear sunscreen any time you go outside — but are you wearing enough?

“It is important to understand that the sun protection factor (SPF) of a sunscreen is determined by using optimal amount of sunscreen,” says Dr. Thomas Chu, Assistant Professor of Dermatology. “The general rule of thumb is to use approximately two milligrams of sunscreen per one square centimeter of skin, which adds up to about two tablespoons of sunscreen.” He adds that the face alone would require a nickel-sized amount.

In addition to using the right amount, it’s important to reapply when needed. “If you are in the sun, you should reapply every two hours,” Dr. Chu says.  “If you are swimming, sweating heavily or toweling off, it should be even more often.”

He also says that the SPF should be at least 30 or higher for extended time outdoors. “Because people may under-apply sunscreen, I personally recommend that the higher the SPF, the better protection it offers.”