Sizing Up Sunscreen

Dermatologists, however, are not buying it. "Currently, there are no truly effective ways to measure the strength of UVA protection in sunscreens," says Hensin Tsao, an assistant professor of dermatology at Harvard University. While sunscreens have begun using labels like "broadspectrum" to indicate comprehensive UVA/UVB protection, no federal guidelines regulate how sunscreens can use the term and what level of protection it indicates. Says Darrell Rigel, a clinical professor of dermatology at New York University,  "Anyone can put the words broadspectrum on a bottle so there's no easy way for the consumer to understand the labeling."

Overexposure to either UVA or UVB rays can lead to serious consequences—8,000 Americans die of melanoma each year, a form of skin cancer often caused by too much UV-exposure. "There are all these reasons to use sunscreen but this labeling is making it hard to do so correctly," says Rigel.

Looking for particular characteristics that aren't on the label, he says, can help make sunscreen decisions easier and smarter. Here are tips for navigating the sunscreen aisle:

SPF still matters: While SPF does not say everything about a sunscreen, it should still be an important factor in selection. Rigel suggests never going lower than 30.

Be ingredient savvy:   Unlike SPF, there is no quick and easy number to indicate a sunscreen's strength in blocking UVA rays. The best way to tell whether you are getting adequate UVA protection is to take a look at the ingredients. There are two ingredients that Rigel says are a good indication that you're UVA-safe: aveobenzone or parsol 1789.

Stay stable: While UVA-blocking ingredients are important, they also tend to cause the sunscreen to break down faster in the sun. This is why a third element is also necessary: ingredients to stabilize the sunscreen. Neutrogena with Helioplex Technology or anything with Mexoryl are Rigel's top choices for stable sunscreens.