Now that summer is in full swing, it's big-time beach time, and that can often mean sunburn. Living in Hawai'i, sunscreen should be something we put on before we step out the door every day of the year. However, it can be hard to remember to protect our skin.

We also live with the illusion that if we wear a sunscreen, we won't get burned.

Wrong, says an article in Harvard Medical School Publications. Throngs of beach-goers go out with their SPF 15 or 30 or 45 slathered on but still manage to burn their skin. How come?

APPLICATION

The problem usually isn't with the sunscreen, but with how it's applied. Most people don't apply enough, or they don't reapply it frequently enough to be effective.

The American Academy of Dermatology recommends reapplying sunscreen immediately after swimming, or every two hours if you stay out of the water. In fact, the academy said that people who wait more than 2 1/2 hours to reapply have five times the chance of getting sunburned as those who reapply every two hours.

The AAD also advises people to use about a shot glass full of sunscreen for adequate coverage of exposed areas of the body, and to apply sunscreen about 15 to 30 minutes before going outdoors to allow it time to soak into the skin.

WHAT'S NEW

There are two new sunscreens, the American Academy of Dermatology reports, that provide longer-lasting protection against UVA and UVB rays: Anthelios SX and Helioplex.

Research shows that Anthelios SX, which was approved by the FDA in 2006, retains 80 percent of its UVA protection and 90 percent of its UVB protection five hours after application. The product combines a new UVA absorber called ecamsule with UVB absorber avobenzone and UVA absorber octocrylene.

Helioplex is a stabilized formulation of avobenzone and oxybenzone, UVB and UVA absorbers.

Helioplex and Anthelios SX appear to be comparable in sun protection and stability, the newsletter reports.

The academy recommends using sunscreen with an SPF rating of at least 15. People with fair skin or at high risk for skin cancer may want to go higher.

The higher a sunscreen's SPF rating, the longer it protects against sun exposure. But that's just part of the equation.

The SPF rating only measures how well a sunscreen blocks or absorbs UVB rays. That's why the American Academy of Dermatology and federal public health agencies advise using a sunscreen that protects against both UVA and UVB rays.

Products labeled "broad spectrum" often contain several different sun protection ingredients in order to cover the broadest possible range of UV radiation. But to what extent they do so is difficult to determine, because there is no good method of measuring how well a sunscreen protects against UVA, the report said. It's an issue the FDA is grappling with in developing new sunscreen labeling regulations.

In the meantime, clean out your medicine cabinet to get rid of sunscreens that may be out of date and therefore less protective; slather on your most potent full-spectrum sunscreen half an hour before heading out the door; and stick that sunscreen in your beach bag for a sun-safe holiday weekend.