Your summer sunscreen guide: What to use and how to wear it

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This story was updated on June 2 to clarify the position of Emily Brewer.


Hey sunshine, summer is here — the season we all look forward to for longer, brighter days. Whether you are sitting poolside or strolling around town, there is nothing more important than making sure you protect your skin from the sun's ultraviolet rays.

Most skin cancers are caused by ultraviolet radiation exposure, according to the American Cancer Society. The routine application of sunscreen is one of the most effective ways to prevent skin cancer and reduce the risk of melanoma.

But among the myriad options at your local drugstore, how do you choose the right sunscreen? And how do you apply it, for that matter?

Generally, experts recommend using about an ounce of sunscreen for the body, or the amount that would fill a shot glass.

According to Chattanooga nurse practitioner Emily Brewer, chief executive officer of The DERM Center, "For the face, the simplest way to measure how much to apply is by using the two-finger rule. You want to apply sunscreen to the full length of your index finger and middle finger and then apply that to your face."

There are two common forms of sunscreen: chemical and physical.

Chemical sunscreen tends to be thinner and easier to rub into the skin, according to Chattanooga's Galen Dermatology.

"Chemical sunscreens allow UV light into the skin," Brewer says. "However, once the light is absorbed into the skin, the chemicals create a reaction in which UV light is converted to heat, and the heat dissipates from the skin."

The lightweight nature of chemical sunscreen allows it to work well under makeup and moisturizers. Though chemical sunscreens can sometimes be skin irritants, and the amount of chemicals absorbed into the bloodstream continues to be a concern for some, Brewer says.

Those wary of the chemical option may consider physical sunscreen.

Physical or mineral sunscreens, composed of ingredients like zinc oxide and titanium dioxide, tend to be thick and can leave behind a white cast to the skin, according to Brewer. In recent years, companies have worked to produce tinted mineral sunscreens to help match darker-pigmented skin types.

"Mineral sunscreens are made of very small particles that sit on the skin's surface and physically prevent UV rays from penetrating the skin," Brewer says. "The ingredients are recognized by the FDA as safe and effective, making it a good choice for patients with more sensitive skin."

Sunscreen application is recommended for all skin types and skin colors and can be applied to those as young as 6 months old, Brewer says. Daily application of sunscreen also fights against premature aging.

For more guidance on sunscreen, Brewer recommends reaching out to a dermatology provider, though she emphasizes the importance of using a broad-spectrum sunscreen that has a sun protection factor (SPF) of 30 or greater.

Moreover, the Skin Cancer Foundation recommends using a water-resistant sunscreen and reapplying it every two hours.

"It's the consumer's choice whether to use a mineral versus chemical sunscreen," Brewer says. "Both are considered safe and effective."