Wear it. Wear plenty of it. And this summer is the first season for the new FDA regulations. Here’s what you need to know about labels and ingredients from Dr. Alan Friedman of Montefiore Medical Center.

Water-resistant

Sunscreens claiming to be waterproof and sweat proof are no longer on the shelves. In their place are 40- and 80-minute water-resistant sunscreens. They offer sun protection for a limited time when exposed to water. Choose the 80-minute water-resistant product and reapply after swimming or toweling off.

Sun Protection Factor (SPF)

Some people think that SPF measures the length of time users can be in the sun before getting sunburned. Not so. SPF defines the amount of ultraviolet B (UVB) radiation needed to cause sunburn, even while sunscreen is on. Sunscreens with SPF 2 through SPF 14 can prevent sunburn, but they provide no protection against skin cancer or premature skin aging. Such sunscreens must now carry a warning label stating, “Spending time in the sun increases your risk of skin cancer and early skin aging. This product has been shown only to help prevent sunburn, not skin cancer or early skin aging.”

The FDA has yet to rule on whether products with SPF values higher than 50 provide extra protection compared to ones with SPF values of 50.

For a sunscreen to reach its listed SPF, a full ounce (think of a shot glass full) needs to be applied. Recent research shows that people only apply 20–25% of this amount, unknowingly lowering the protection factor of their sunscreens. Best choice: SPF 30 or higher and plenty of it.

Broad spectrum

Until the final FDA requirements took effect, sunscreens were only evaluated and regulated for their ability to protect against UVB radiation, as measured by SPF. Now, sunscreens also are evaluated for their UVA protection. Sunscreens labeled as “broad spectrum” protect against both UVA and UVB radiation.

“UVA penetrates deeper into the skin where it can accelerate skin aging and cause skin cancer. I call UVA the silent killer, because unlike UVB, it does not cause sunburns so it is hard to tell if you are getting harmful exposure,” said Dr. Friedman. “Broad spectrum sunscreen use should not be limited to beach outings or summer months. Recent research showed that the skin aging process is significantly slower among people who apply broad spectrum sunscreen daily, year round.”

Read the ingredients

Sunscreen companies use different mixtures of ingredients. Choose products that have a variety of sun-blocking agents. Dr. Friedman recommends selecting a sunscreen that contains several organic sun-blocking agents such as ecamsule, cinoxate, octyl salicylate, and benzophenones (oxybenzone). The different chemicals work in synergy to create greater sun protection than any one ingredient alone. Also, combining multiple agents allows companies to use less of each, which decreases the risk of any associated irritation.

The best products also contain mineral, physical sun-blocking agents like zinc oxide and titanium oxide. In the past, these ingredients appeared chalky and left skin greasy, but newer products deliver “micronized” thinner, sheerer formulations. Products that contain talc and bentone gel prevent these ingredients from clumping, and improve cosmetic appearance.

Look for pH stabilizers to hydrate and fortify the skin, like dimethicone, cyclomethicone, and sodium phosphate. When the skin is hydrated, its can heal and repair itself much more quickly.