How much sun is safe, and does the tanning bed really cause skin cancer?

UV radiation from the sun and from tanning beds demonstrably causes skin cancer. Between 60 and 70 percent of all melanomas are attributed to UV exposure. Skin cancer is the most common cancer in the world, and the number of cases continues to rise. This is not a statistical suspicion but a causal relationship that is widely supported^1,2,3.

Tanning beds are not a safe alternative to the sun. UV light damages the DNA of skin cells, suppresses the skin's local immune defences, and causes inflammation. Together, these three steps lead to melanoma formation. The more frequently and the longer you use a tanning bed, the greater the cumulative damage^4,5.

Yet some sun is biologically necessary. Your skin produces vitamin D through sunlight, and more than half of the world's population is at risk of deficiency, partly because people spend too little time outdoors. A vitamin D deficiency is associated with bone conditions such as rickets and osteoporosis. It may also play a role in certain cancers, autoimmune diseases, and infectious diseases, but the evidence for many of these conditions is far from equally strong⁶.

How much sun is 'safe' varies from person to person. Your skin pigmentation, age, the time of day, the season, and the use of sunscreen all determine how much vitamin D you produce. Fair skin produces it more quickly but also burns more quickly. A rough rule of thumb from the research: short, regular exposure of the face, arms, and hands outside of peak hours, without burning. Burning is the clearest sign that you have gone too far^7,8.

Prevention genuinely works. Public campaigns about sensible sun exposure have noticeably reduced mortality from melanoma. Researchers consider most skin cancers to be preventable. In practice: avoid sunburn, skip the tanning bed, wear protective clothing and sunscreen in the intense midday sun, but do not cut out moderate daily exposure altogether.