Keira McGowan lies across a towel in a blue bikini. The UV index is nine, McGowan said, her legs stretched out and glistening in the sun.
McGowan, a college student from Bensenville, is one of the young women closely tracking the Ultraviolet (UV) Index, an international standard measuring ultraviolet radiation on a scale of 1 to 11. After seeing the high reading, she and a friend planned to spend the morning tanning on Clark Street Beach.
McGowan checks the UV index up to 20 times a day hoping to maximize sun exposure at peak tanning hours, she said. “When I wake up, I’ll check it right away. I check it every hour.”
Created to help people limit harmful sun exposure, the UV index serves as a tanning forecast for many teens and young adults. In a culture where bronzed skin remains tied to beauty standards, the easily accessible reading in the Apple Weather app has become a daily reference point.
The percentage of dermatology patients who are looking at the UV index and using it to make behavioral decisions is increasing, said Northwestern Medicine dermatologist Dr. Paras Vakharia.
Some patients use the index as intended, Vakharia said, checking it to decide when to wear sunscreen and minimize sun exposure.
Others, like McGowan, use it for the opposite reason.
Aleksandra Piaszcznyski, a rising college freshman at Lewis University from Rosemont, said many of her high school peers frequently checked the index to plan their days around getting outside at high UV levels.
“I check it to see the best days to go out, because if the UV is bad, then what’s the point?” she said.
McGowan says she cares about her health and does not want to get skin cancer. But she still likes soaking in the sun. Tanning is only part of the appeal, she said. Spending time outside when there is a high UV makes her feel happier and calmer.
Dermatologists warn that treating the UV index as a guide for maximizing time in the sun when it is most powerful undermines its intended purpose and can encourage harmful exposure.
“A tan is our body’s way of telling us that our DNA is damaged,” said Dr. Peter Lio, a dermatologist at Medical Dermatology Associates of Chicago. Optimizing tanning is effectively optimizing skin damage, he said.
Still, the sunlight can have benefits, including supporting vitamin D production and encouraging people to spend time outdoors, so Lio does not believe people should avoid the sun entirely, he said.
“There’s probably some middle path, getting some careful sun exposure and using the UV index as it was intended to avoid the time when it’s at least four or above,” Lio said. “Try to focus on the times when it’s lower, where you can safely spend some more time outside without worrying.”
Whether used to avoid the sun or seek it out, the UV index has become a routine piece of daily information for many young Americans.
“I have it on the top of my phone, on my screensaver,” McGowan said. “At the top it says the date, and then it says the UV right above the time.”
