Alivia Parker, 21 months, runs through circles of spraying water on a 100-degree day in Montgomery, Ala., Tuesday, June 14, 2011. Parker is wearing sunscreen with an SPF of 100. (Dave Martin/AP)

Earlier this week, the Food and Drug Administration (FDA) unveiled several new rules for sunscreen labels, which go into effect in 2012. Years in the making, these rules aim to better protect consumers from the harmful effects of the sun’s ultraviolet-A and ultraviolet-B radiation and prevent sunscreen manufacturers from using words like “sunblock” and “waterproof” on their products.

Under the new FDA guidelines:

- Sunscreens may only be labeled “broad spectrum” if they protect the skin from both UVA and UVB rays.
- Any sunscreen with a sun protection factor (SPF) of less than 15 must have a warning label that the product does not protect the skin from sunburn, premature aging, and skin cancer.
- Consumers will no longer see the familiar labels sunblock, waterproof, and sweatproof. Instead, manufacturers may only call their products water-resistant and must indicate how often they must be reapplied.
- Lastly (and perhaps most surprising to the extra sun-cautious): sunscreens can no longer carry an SPF label greater than 50.

Why a cap on the SPF number? Keep reading to find out…

What is the SPF?

SPF vs. UVB protection. An SPF of 30 only gives you four percent more protection than an SPF of 15. (EPA)

“UVB protection does not actually increase proportionately with a designated SPF number. For example, an SPF of 30 screens 97 percent of UVB rays, whereas an SPF of 15 screens 93 percent of UVB rays, and an SPF of 2 screens 50 percent of UVB rays. However, inadequate application of sunscreen may result in a lower SPF than the product contains.”

The relationship between SPF and UVB protection is depicted above. Note that even the highest SPF does not offer 100 percent protection from the sun’s UVB rays.

What’s the difference between UVA and UVB rays?

Unlike UVB rays, which are the main cause of sunburn, UVA rays penetrate deeper into the skin and contribute to wrinkles and premature aging (more on this topic here). The FDA regulations let consumers know that they are only getting protection from UVA rays on sunscreens labeled “broad spectrum.”

How much sunscreen should I use?

Each person is different, but the AAD and Skin Cancer Foundation both recommend using one ounce (or enough to fill a shot glass) to cover the body in one application.

What makes it so easy to burn at this time of year?

Although temperatures in our region peak in mid- to late July, maximum solar radiation occurs during the month of June. Assuming skies are clear, if you are outside over the noon hour, your skin will burn fastest the week of the summer solstice compared to any other time of year, regardless of the outside air temperature (check out the daily UV index here). ABC7 Senior Meteorologist Bob Ryan offers a useful “shadow graphic” explaining when it’s best to avoid the sun.

The bottom line

Whether or not the FDA’s new labeling requirements clear up confusion on sun protection, always remember that sunscreen must be applied liberally and consistently for it to be most effective.

Sources and additional reading:

FDA cracks down on sunscreen

The Burning Facts (US Environmental Protection Agency)

Sunscreen Q&A (American Academy of Dermatology)

UVA vs. UVB: How do they affect the skin? (Skin Cancer Foundation)

High SPF sunscreens: Are they better? (WebMD)