Shining light on sun protection products

Originally Published: May 31, 1996 - Last Updated / Reviewed On: August 6, 2010
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Dear Alice,

I find choosing among all of the available sunscreens and sunblocks to be very confusing. Of the following three products I am currently using, which one is giving my skin the most protection: sunscreen SPF 30 with UVA, UVB, and IR sun protection; sunblock SPF 17 with UVA, UVB, and IR sun protection; or, sunblock SPF 50 with UVA and UVB sun protection? By the way, what is the difference between a sunSCREEN and a sunBLOCK?

Desperately Seeking Protection

Dear Desperately Seeking Protection,

Walk into any pharmacy, and you'll find a dizzying array of sun protection products. Amidst a sea of marketing claims, it's difficult to know which products offer the best defense against the sun. Some basic info about sunbeams may illuminate part of the confusion around sunscreen. The sun actually sends out several different kinds of rays:

Ultraviolet (UV) rays: Invisible UV rays come in three types — A, B, and C — the last of which are the most dangerous. Thankfully, the earth's atmosphere absorbs most of the sun's UVC rays before they reach your skin.
UVA rays penetrate skin and may damage the bottom layer that produces new skin cells. Over time, this damage may lead to wrinkles, age spots, and skin cancer.
UVB rays may damage the outer layer of skin, inflaming blood vessels and causing sunburn. However, a small amount of UVB exposure (15 minutes a day) does a body good by producing Vitamin D, an essential nutrient that helps the body absorb calcium.
Infrared (IR) rays: IR rays carry visible light and warmth from the sun. Along with UV exposure, IR radiation contributes to skin damage and the redness of sunburn. Sunscreens that claim to protect against IR rays may offer some added benefit over traditional sunscreens, but research about the efficacy of these products is still unclear.

The best way to protect yourself from the sun and reduce your risk of skin cancer is simply to limit your exposure to these rays. When you go out, consider staying in shaded areas with less direct sun. If you are under the sun, consider covering up with clothing, hats, and sunglasses that help protect you from the sun's rays. Sunscreen offers additional protection from sunlight. Note that no product blocks out all the sun's harmful rays, so the United States Food and Drug Administration (FDA) has banned the term "sunblock." To determine which sunscreen works best for you, consider the product contents and its SPF.

Physical sunscreens form an opaque barrier that scatters UV rays away from the skin. These products contain zinc oxide or titanium dioxide, both of which reflect UVA and UVB rays. In the past, physical sunscreens gave the skin a white pasty look, but newer versions blend in more. Rather than reflecting light, chemical sunscreens actually absorb UV rays before they penetrate your skin. Ingredients like ayobenzone or oxybenzone soak UVA or UVB rays. A newer ingredient called meroxyl protects against both kinds of rays. For the best protection, look for a product that says "broad spectrum protection."

The next consideration is SPF, short for sun protection factor. SPF measures the proportion of UVB rays that the sunscreen filters out (currently, there's no rating system for UVA protection). The American Cancer Society (ACS) recommends using at least SPF 15, which shields you from about 93 percent of UVB rays. SPF 30 filters out 97 percent of UVB rays, but above that number you get little extra protection. A common misconception about sunscreen is the higher the SPF, the longer you may stay in the sun, which simply isn't true. Sunscreens also need to be reapplied every two hours for it to protect your skin.

In your search for the best sunscreen, it's probably a toss-up between your bottle of SPF 30 and the SPF 50. Until the research moves forward, there's no way to tell if the IR protection in the first product or the higher SPF in second is a better buy. For now, savvy sunscreen shoppers may simply look for products with "broad spectrum" protection in at least SPF 15. Hope that helps shine light on sun protection products!

Alice