Sun Protection Myths That Dermatologists Keep Correcting

This is one of the most consequential myths dermatologists encounter. People with deeper skin tones do have higher levels of melanin, which provides a natural SPF equivalent of roughly 13 or lower — far below the SPF 30 minimum recommended by dermatology organizations. UV exposure can still cause hyperpigmentation, premature aging, and, critically, melanoma in people of all skin tones. Because skin cancer is often diagnosed at later stages in people with darker skin — partly due to this myth — the outcomes can be more serious. Everyone benefits from daily broad-spectrum sunscreen use.

Clouds block visible light, but they scatter rather than absorb UV radiation. Up to 80% of UV rays can pass through overcast skies, according to general guidance from the U.S. Environmental Protection Agency. UV index levels are also elevated at higher altitudes and can reflect intensely off snow, sand, and water. Winter sun — especially in snowy environments — can cause significant UV exposure. A daily sunscreen habit, applied every morning regardless of the forecast, is far more reliable than trying to judge UV intensity by how bright it looks outside.

SPF 30 filters approximately 97% of UVB rays, SPF 50 filters about 98%, and SPF 100 reaches roughly 99%. These are meaningful distinctions in clinical settings, but in real-world use they're largely erased by how little sunscreen most people actually apply. Studies suggest most people apply only 20–50% of the amount used in official SPF testing, which dramatically reduces effective protection regardless of the number on the label. Applying a generous, even layer — and reapplying every two hours when outdoors — delivers more protection than doubling the SPF but skimping on coverage.

Standard glass blocks most UVB rays (the ones primarily responsible for sunburn) but transmits a significant portion of UVA rays. UVA penetrates more deeply into the skin and is associated with photoaging — wrinkles, sunspots, and loss of elasticity — as well as a contribution to skin cancer risk. People who spend long hours near windows, whether working from home, commuting, or sitting by a glass-fronted office, accumulate meaningful UVA exposure over time. Broad-spectrum sunscreen applied each morning addresses both UVA and UVB exposure, indoors or out.

Dermatologists frequently see sun damage and skin cancer on commonly overlooked areas: the backs of hands, the tops of ears, the lower lip, the neck, and the chest. The scalp, particularly along hair part lines, is another vulnerable spot often missed entirely. For areas where applying lotion is awkward, SPF-protective clothing, wide-brimmed hats, and powder or spray sunscreen formulas can help fill the gaps. A thorough application routine accounts for the full body surface that will be exposed — not just the face.