As summer calls millions to spend more time outdoors under the sun's rays, skin protection becomes vital.
One in five Americans will develop some kind of skin cancer, according to the Skin Cancer Foundation (SCF). Ninety percent of nonmelanoma skin cancers are linked to exposure to ultraviolet (UV) radiation from the sun.
AccuWeather spoke to several experts about sunscreen myths, facts and helpful tips as leisure activities head toward pools, beaches and other outdoor venues.
What SPF should people be using?
Most experts recommended a sunscreen that contains between 35 and 50 SPF, regardless of skin tone.
"It is true that darker skin types are more protected from UV radiation, which is one of the factors associated with skin cancer," Dr. Jerry Brewer, a dermatologist at the Mayo Clinic, said.
However, those with darker complexions can still sunburn and sustain damage from UV radiation.
"Everyone needs a broad-spectrum sunscreen, meaning it offers protection from UVA and UVB rays," Dr. Lauren Ploch, a dermatologist based in Augusta, Georgia, said.
UVA rays (longer rays) account for up to 95 percent of the UV radiation reaching the Earth's surface, according to the SCF. UVB rays (shorter rays) damage the skin's epidermal layers, the main cause of sunburn.
Is it worth spending more money on an SPF over 35?
Not necessarily. No sunscreen blocks 100 percent of the sun's rays. At SPF 30, 97 percent of the rays are blocked. At SPF 50, 98 percent are blocked. There is no scientific evidence that proves a sunscreen with an SPF higher than 50 can offer better protection, according to the American Academy of Dermatology.
How often should you apply sunscreen?
At least every two hours. If you're going in the water, reapply every 40 to 80 minutes, Dr. Ploch said, and make sure to reapply as soon as you get out.
"If you're not in the water, you can probably reapply every 60 to 90 minutes," she said. "But if you're outdoors and sweating a lot, think of that as being in the water."
How much sunscreen should you apply?
Most dermatologists recommend applying a shot-glass size of sunscreen to cover the entire body upon each application.
"Making sure you're hitting all of the exposed skin is just as important," Dr. Ploch said.
She recommends applying sunscreen all over the body before heading out to the beach or the pool, letting it dry up a bit before skin is exposed to the sun.
"If you're in a bathing suit, you may not feel as comfortable applying to those areas that extend under the bathing suit," she said.
Suits loosen up and move throughout the day, and people will often miss areas that were not originally exposed, she said.
What is a water-resistant sunscreen? Why is it not waterproof?
In 2012, the U.S. Food and Drug Administration banned manufacturers from marketing their sunscreens as "waterproof" and "sweatproof."
Most sunscreens are tested for only 40 to 80 minutes in the water, Dr. Ploch said.
"Then people would go in the water all day and not reapply, thinking they were safe since the sunscreen was labeled as waterproof," she said.
No sunscreen is truly waterproof and must be reapplied at least every 80 minutes to keep skin protected.
Is spray sunscreen as effective as a cream?
Most experts advise against using a spray sunscreen.
"I don't think they provide the same coverage as a lotion," Dr. Ploch said.
While they might be more convenient, people are less likely to spray the required amount of sunscreen to provide effective coverage. In order to receive the full benefits, the spray should build up until it looks white, and then it needs to be fully rubbed in. Most people don't do that, Dr. Ploch said.
There could be health hazards associated with sprays as well.
"We don't know the effects of nanoparticle or chemically-inhaled sunscreens though an aerosol spray," she said.
Can you build up a tolerance to sunscreen?
No, sunscreen will always be as effective as it originally was for each individual.
Is organic sunscreen as effective as regular sunscreen?
"Organic and non-organic is different in sunscreen than it is food," Dr. Ploch said. "In science, organic means carbon containing."
Sunscreens with zinc and titanium, which are two of the safest ingredients, would be considered non-organic.
She prefers to look at them as mineral and chemical sunscreens. The minerals zinc and titanium can be found in nature.
Sunscreens with zinc and titanium are often stickier and thicker, which may be unpleasant for some consumers. Those minerals provide a physical blocker, rather than a chemical blocker.
"I do prefer a physical blocker. The reason for that is they provide a barrier on your skin to prevent entry of the sun rays," she said.
With a chemical blocker, the rays are absorbed into the skin then deactivated by the chemicals.
What makes a sunscreen feel greasy? Why does it have a distinct smell?
Most sunscreens are formulated to spread easily and provide even coverage, giving way to a greasy feel, Dr. Ploch said.
"Usually the greasier, stickier, the thicker something is, the better it's going to work for you," she said.
In terms of the smell, it's more of the absence of chemicals than an added ingredient that makes it smell a certain way.
Most skincare products contain a masking fragrance to make them more appealing to a consumer, but that is often not the case for sunscreen.
"A lot of care goes into not putting so many products in them, because that can affect the photostability of the active ingredient, so most sunscreens don't contain a masking fragrance," Dr. Ploch said.
What is the difference between a baby sunscreen and a regular sunscreen?
Sunscreen formulated for babies uses physical blockers like zinc and titanium, as those minerals aren't absorbed into the skin.
Kids under six months old should not be using any type of sunscreen. Those under two years shouldn't be using a chemical sunscreen.
Dr. Ploch actually recommended using a baby sunscreen for all ages, preferring the protection from a physical blocker.
Do sunscreens expire?
Yes. All sunscreens will display an expiration date when they will not be as effective.
"You should always keep sunscreen that has not expired and is ready for use," Dr. Brewer said.
Is the sunscreen in some beauty and skincare products as effective as regular sunscreen?
Yes, if the product offers a high enough SPF level. However, like all other sunscreens, the product should be reapplied every two hours to maintain protection from the sun.