The sun delivers both benefit and risk. Ultraviolet radiation fuels vitamin D production in the skin, bolstering bone health and immune function. But excessive UV exposure damages skin cells, triggering mutations that spiral into melanoma and other cancers.
UV radiation comes in three types. UVA penetrates deep into the skin and accelerates aging. UVB burns the surface layers and drives melanoma risk. UVC gets filtered by the atmosphere, so it poses no threat on Earth's surface. The UV Index, measured on a scale of 0 to 11 and beyond, tells you how intense solar radiation is at any given moment and location.
Protection starts with sunscreen. Broad-spectrum formulas block both UVA and UVB rays. The SPF number indicates UVB defense, not UVA coverage. SPF 30 blocks roughly 97 percent of UVB rays. SPF 50 gets to 98 percent. Most people apply far less sunscreen than needed for full protection. Dermatologists recommend a shot glass full (about one ounce) for the whole body.
Timing matters. UV rays peak between 10 a.m. and 4 p.m. Seek shade during these hours, especially in summer. Wear protective clothing, hats, and sunglasses when outdoors. UV-blocking fabrics offer better defense than cotton alone.
Children face particular risk. Their skin hasn't developed full protection mechanisms. Babies under six months should stay out of direct sunlight entirely. Older children need sunscreen reapplied every two hours, or more frequently after swimming.
The goal isn't avoiding sun exposure entirely. Brief, unprotected exposure generates vitamin D without triggering skin damage. The balance tilts toward protection in high-UV environments and for those with fair skin, family histories of melanoma, or previous sun damage.