This summer, TikTok and Instagram feeds have been full of a new ritual: “checking the UV.” Gen Z content creators are tracking the daily UV index — not to avoid the sun, but to head outside when it’s strongest for what they see as the “optimal” tan. At the same time, some social media influencers are spreading claims that sunscreen is harmful or unnecessary, a trend that has dermatologists increasingly concerned.

While online conversations about sun exposure are trending, the risks of UV radiation are real and cumulative. Peak UV exposure affects all skin tones, from sunburn and premature aging to hyperpigmentation and, in some cases, skin cancer.

Y. Linda Liou, DO, an assistant clinical professor in the Department of Dermatology at UC San Diego School of Medicine, offered to explain the science of the UV index, the real risks of intentional sun exposure, and how to enjoy sunny days without paying for it later.