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July 03, 2024

Why doctors recommend sunscreens with SPF 30 or higher

It takes one hour for a person wearing it to absorb the same amount of cancer-causing rays as someone going two minutes without sun protection.

Prevention Skin Cancer
Sunscreen Skin Cancer Gregg Pachkowski/USA TODAY NETWORK

Knowing how to choose a sunscreen and how to apply it is critical to preventing skin cancer, which is more common than all other cancers combined.

More Americans are diagnosed with skin cancer every year than all other types of cancers combined. At least 1 in 5 U.S. adults will be diagnosed with skin cancer by the age of 70, according to the Mayo Clinic.

With summer in full blast – and hotter-than-usual temperatures forecasted throughout the country – it's important to know how to best protect your skin.

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The American Cancer Society recommends using sunscreen with broad spectrum protection against both UVB and UVA rays. UVA rays have a longer wavelength, penetrate deeper into skin, are associated with inflammation and skin aging, and can cause skin cancer. They account for 95% of the light that reaches our skin. Though UVB rays account for just 5% of the light that reaches us and are shorter, they cause the cell mutations that drive cancer.

To protect against ultraviolet radiation, sunscreen should not only be broad spectrum but also have a sun protection factor of 30 or higher. Wearing an SPF 30 sunscreen means your skin gets the equivalent of one minute of UVB rays for every 30 minutes you are exposed to the sun – so one hour in the sun wearing SPF 30 sunscreen is the same as spending 2 minutes in the sun without sunscreen, according to the American Cancer Society

A sunscreen of 50 SPF is even more protective. A 30 SPF sunscreen allows about 3% of UV rays to reach the skin, whereas a 50 SPF sunscreen only permits about 2% to reach the skin. 

"That may seem like a small difference until you realize that the SPF 30 is allowing 50 percent more UV radiation onto your skin," Dr. Steven Q. Wang, medical director of dermatologic oncology and dermatologic surgery at the Hoag Family Cancer Institute in Irvine, California, wrote last year in a post for the Skin Cancer Foundation.

For the best protection, make sure to choose a lotion, gel or spray that is water resistant and reapply it every two hours and after you swim or towel off, according to the American Cancer Society. The U.S. Food and Drug Administration no longer allows companies to claim that their products are waterproof because water and sweat can wash off sunscreen. And those of us who have scorched their toes at the beach will remember to apply sunscreen to every inch of exposed skin, including face, neck and ears.

Although spray sunscreens are convenient for kids and hard-to-reach areas, health experts recommend using two to three tablespoons of sunscreen to cover the body, which might be hard to achieve with a spray.

If you get sunburned, the American Academy of Dermatology Association recommends the following steps:

• Immediately get out of the sun.
• Take frequent cool baths or showers to help relieve the pain.
• Apply a moisturizer that contains aloe vera or soy to help soothe sunburned skin.
• Consider taking aspirin or ibuprofen to help reduce any swelling and discomfort.
• Drink extra water to prevent dehydration that can come with sunburn.
• Do not pop blisters that may appear and allow them to heal, applying petroleum jelly.

See a doctor if your skin blisters and you have symptoms that include:

• bright red, oozing skin
• severe pain
• fever
• feeling extremely cold or shivering
• headache
• nausea and vomiting

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