A man shielding his eyes from the sun.

Everyone knows that the single best way to avoid skin cancer is to shield your skin from the sun’s damaging ultraviolet (UV) rays. Even getting just one sunburn every two years, according to Cancer Research UK, can triple your risk of melanoma, the most dangerous form of skin cancer.

But findings from a large survey of more than 31,000 adults living in the U.S., published today in the journal JAMA Dermatology, reveal that many Americans may not be consistently taking the risk of sun damage as seriously as they should.

“We found that about a third of U.S. adults are getting sunburned each year,” says Dawn M. Holman, M.P.H., lead author of the study and a behavioral scientist at the Centers for Disease Control and Prevention’s Division of Cancer Prevention and Control. “And that number goes up with higher risk groups.”

Read More About Sun Safety

Those who were Caucasian, young, and had sensitive skin got the most sunburns, according to the study. But even people with darker skin, who are typically thought to be at a lower risk for sunburn, were susceptible, too.

“The big picture, which is concerning given the link between sunburn and the risk of skin cancer, is how common sunburn is,” says Holman. 

What the Study Found

As part of interviews for the long-running National Health Interview Survey, the researchers asked specific questions about sun safety and related behavior in 2015.

These included questions about sun habits, such as how often they got a sunburn in the previous year, or whether and how they protected themselves on sunny days—such as by staying in the shade, wearing protective clothing and hats, or wearing sunscreen with an SPF of at least 15.

The researchers also asked subjects questions about whether their skin was sensitive to the sun, and about lifestyle factors, such as exercise, smoking, and drinking habits, and whether they used indoor-tanning booths or self-tanning products.

The findings were concerning: 34 percent of all respondents reported having had at least one sunburn in 2015, with the highest rates among those who were Caucasian, age 18 to 29, and had sensitive skin.

People who exercised, used self-tanners, were binge drinkers, and were overweight or obese were also more likely to have experienced sunburn than others.

“People who are not caring for one aspect of their health might be more likely to engage in other risky behaviors,” says Holman. And those who exercise may get more sunburns because they’re outside more than others.

But other findings were more surprising. Those who regularly used sunscreens, for example, were more likely to burn than those who didn’t. This may be because some sunscreen users may have a false sense of security or don’t follow label directions properly, says Holman. Others may simply use sunscreen to justify staying outdoors longer.

And 30 percent of Hispanics and 13 percent of non-Hispanic blacks reported getting burned.

“Within each racial and ethnic group, there’s a wide range of skin types and tones, and that nuance hasn’t been acknowledged in the past in research,” says Holman. Bottom line, she says, is “all races and all ethnicities can benefit from sun protection.”

Holman says she wants the results of this study to encourage everyone to protect their skin and to know that doing so can be beneficial. “But you need to plan ahead and make sun protection part of your daily routine,” she says.

Here are five facts about sun safety. 

Fact: We All Need Good Sun-Safety Habits

Don’t think that tanning easily, not having skin cancer in your family, or other factors means you can go without protection.

“All people, no matter your skin color, age, or family history of skin cancer, are susceptible to damage from harmful UV rays” says Consumer Reports' chief medical adviser, Marvin M. Lipman, M.D.

For example, the new study found that while sunburn is most common among young adults and those with sensitive skin, about 15 percent of people age 65 or older experienced sunburn each year. “Older adults grew up with different social norms related to sun exposure (potentially resulting in greater total lifetime sun exposure),” the study authors wrote, “and are rarely targeted by sun-safety interventions.”  

Fact: Sunscreen Alone Is Not Enough

Doubling up on protection is important because even the best sunscreen applied properly can’t give you 100 percent protection from UV rays. “We encourage people to use clothing to cover skin, sunglasses to protect eyes, and wide-brimmed hats to cover the ears and the back of the neck,” says Holman. It’s also important to seek shade, whether it be a beach umbrella or a leafy tree. Minimizing sun exposure between 10 a.m. and 4 p.m., when the rays are the strongest, is also a good strategy.

Fact: A Little Sunscreen Won't Cut It

The average sunscreen user applies only 25 to 50 percent of the recommended amount, according to the American Academy of Dermatology (AAD). A recent study published in the Journal of the American Academy of Dermatology, for example, found that among 2,000 people offered free sunscreen at booths placed throughout a state fair, only 33 percent of those who used it applied it to all of their exposed skin. The rest focused only on their faces and arms, leaving other areas exposed.

The AAD recommends applying 1 ounce, or the amount that would fill a shot glass, to cover your entire body at least 15 minutes before going outside. (You may need more or less depending on your body size and what you are wearing.)

Not sure how to choose the best sunscreen? Our sunscreen buying guide can help. 

Fact: Reapply More Often

You’ve smothered yourself from head to toe with sunscreen and can now relax for the rest of the day without any worry, right? Wrong.

“You need to reapply every 2 hours and after swimming and sweating,” says Holman.

And there is no such thing as a safe tan. “A lot of times we find that people trying to get a tan tend to get burned,” says Holman. “We say to avoid tanning altogether.”

Fact: You Need Sunscreen on Cloudy Days

Unlike UVB rays, which are more prevalent in the summer and between 10 a.m. and 4 p.m., UVA rays are prevalent throughout the day—no matter the season or weather—and they can pass through clouds and even glass. According to the AAD, 80 percent of the sun’s harmful UV rays can reach the skin, even if it’s cloudy.

And because UVA rays are less intense, meaning they don’t leave us looking red or feeling hot, they’re potentially more of a stealth threat to your health.