The damage is recognized by the body, which then triggers several defense mechanisms, including DNA repair to revert the damage, apoptosis and peeling to remove irreparably damaged skin cells, and increased melanin production to prevent future damage. Melanin readily absorbs UV wavelength light, acting as a photoprotectant. By preventing UV photons from disrupting chemical bonds, melanin inhibits both the direct alteration of DNA and the generation of free radicals, thus indirect DNA damage. However, human melanocytes contain over 2,000 genomic sites that are highly sensitive to UV, and such sites can be up to 170-fold more sensitive to UV induction of cyclobutane pyrimidine dimers than the average site  These sensitive sites often occur at biologically significant locations near genes. Sunburn causes an inflammation process, including production of prostanoids and bradykinin. These chemical compounds increase sensitivity to heat by reducing the threshold of heat receptor (TRPV1) activation from 109 °F (43 °C) to 85 °F (29 °C). The pain may be caused by overproduction of a protein called CXCL5, which activates nerve fibers.Skin type determines the ease of sunburn. In general, people with lighter skin tone and limited capacity to develop a tan after UV radiation exposure have a greater risk of sunburn. The Fitzpatricks Skin phototypes classification describes the normal variations of skin responses to UV radiation. Persons with type I skin have the greatest capacity to sunburn and type VI have the least capacity to burn.
Sun protective clothing with a SPF rating can also provide additional protection. Artificial UV exposure
The WHO recommends that artificial UV exposure including tanning beds should be avoided as no safe dose has been established. When one is exposed to any artificial source of occupational UV, special protective clothing (for example, welding helmets/shields) should be worn. Such sources can produce UVC, an extremely carcinogenic wavelength of UV which ordinarily is not present in normal sunlight, having been filtered out by the atmosphere. Treatment
The primary measure of treatment is avoiding further exposure to the sun. The best treatment for most sunburns is time; most sunburns heal completely within a few weeks. The American Academy of Dermatology recommends the following for the treatment of sunburn:
For pain relief, take cool baths or showers frequently. Use soothing moisturizers that contain aloe vera or soy. Anti-inflammatory medications such as ibuprofen or aspirin can help with pain. Keep hydrated and drink extra water. Do not pop blisters on a sunburn; let them heal on their own instead. Protect sunburned skin (see: Sun protective clothing and Sunscreen) with loose clothing when going outside to prevent further damage while not irritating the sunburn.Non-steroidal anti-inflammatory drugs (NSAIDs; such as ibuprofen or naproxen), and aspirin may decrease redness and pain. Local anesthetics such as benzocaine, however, are contraindicated. Schwellnus et al. state that topical steroids (such as hydrocortisone cream) do not help with sunburns, although the American Academy of Dermatology says they can be used on especially sore areas.