Sunscreen 101: SPF Explained, and How You Should Apply It

— -- Every morning, Sabrina Walsh of Tiburon, California, feeds her three children breakfast, brushes their teeth and puts sunscreen on them.

The American Medical Association says more Americans than ever are taking precautions against sun damage, but it’s not enough.

“People are not using enough sunscreen and they are not reapplying it often enough,” Dr. Doris Day, a dermatologist, said.

Sunscreen can be confusing. A recent report JAMA Dermatology -- a monthly publication from the American Medical Association – says that only 51 percent of Americans understand what “SPF” means. The term generally appears on sunscreen tubes and bottles.

“SPF” stands for sun protection factor. An SPF of 15 blocks about 95 percent of UV rays. An SPF of 30 will block about 97 percent and an SPF of 50 will block 98 percent, Day said.

Applying it can also be confusing.

“I start with their cheeks and their nose and I kind of move upward with their forehead, and I really like to get their ears, then at that point, we usually move to the spray and we start coating their bodies and moving it up their necks,” Walsh said.

People often forget the ears and the areas where the cheeks meet the neck, Day said.

“We see skin cancer mostly in sun-exposed areas … What happens is, you apply sunscreen [around the nose], you feather it out, you run out by the time you get the periphery, and then you let it go,” she said.

People are also urged to remember to apply sunscreen to their hands.

Parents may be vigilant about keeping their children’s skin protected, but the U.S. Centers for Disease Control and Prevention says only 34 percent of women and 18 percent of men use sunscreen on their faces every day.

“Make sure you apply your sunscreen before leaving the house, then apply it to your kids,” Day said. “My experience is when you apply it on your children first, life calls and you get busy.”

Skin cancer is the most common kind of cancer, with about 3.5 million cases of basal and squamous cell skin cancers diagnosed every year throughout the United States, according to the American Cancer Society.

Melanoma, a far more dangerous kind of skin cancer, is expected to account for more than 73,000 cases of skin cancer in 2015, also according to the ACS.