How it works : Sunburn

It's a little more complicated than a simple heat-and-char process. Immediately after sun exposure, you'll see some pink skin: that comes from dilation of the capillaries in reaction to ultraviolent B rays. "The actual burn you see later comes from series of chemical reactions," say Dr Mehmet C. Ox. Mast cell in the skin release chemicals like histamine and serotonin, triggering more chemical production and inflammation. Whitin 12 hours, skin cells begin to die, and inflammation turn the skin a darker red. UV radiation damages your DNA, setting you up for possible skin cancer and suppressing immunity. But your skin does try to fight back. As soon as you're exposed to UV radiation, cells called melanoctyes release melanin pigments that block UV ray- in the form of a tan that can reflect UV light. You;re heard it before, but it bears repeating. To prevent burns, use a sunscreen that blocks both UVA and UVB ray, and reapply often