Intense sun exposure causes solar dermatitis, also known as sunburn. After intense sun exposure, within a few hours or the next day, the sunburned skin becomes red and swollen, with a burning sensation and stinging pain, and the symptoms reach their peak 12 to 24 hours after sun exposure. In milder cases, the erythema and burning pain begin to subside only after a few days, and patches of scaling and deep brown spots with itching occur. In patients with severe symptoms, in addition to significant redness and swelling of the sun, blistering and blistering occurs, and the burning pain is intense and unbearable when clothes are rubbed together. The conjunctiva can be congested and the eyelids are often excessively swollen or even cannot be opened. In addition to the occurrence of severe dermatitis, there are also symptoms of heat stroke in the form of nausea, vomiting, fever, rapid heartbeat, delirium and even shock, especially when extensive solar dermatitis prevents sweat excretion and is more likely to cause heat stroke. The most likely cause of solar dermatitis is in late spring and early summer, because the skin does not have enough melanin to protect the skin from strong sunlight, a strong sun exposure can cause solar dermatitis, the severity of which depends on the intensity of the light, the length and extent of the sun exposure, and is related to the sensitivity of the individual; people with fairer skin tones are more prone to sunburn, and farmers who are often exposed to the sun are more difficult to be sunburned than urban residents. . Some skin reddens or even blisters for tens of minutes or hours after sun exposure, while others have a slight erythema only the next day. Clothes and umbrellas can cover sunlight to avoid sunburn, but water, snow and deserts can reflect sunlight, so sun dermatitis can occur even though travelers use umbrellas and straw hats to shield their skin from the sun. In addition, the intensity of sunlight can be affected by the smoke in the air, the thickness of the clouds, the size of the humidity and the altitude. Sunlight reaching the ground contains medium-wave ultraviolet (UVB), long-wave ultraviolet (UVA), visible light and infrared light, of which ultraviolet light accounts for 40%. Medium-wave UVB can act directly on the skin’s blood vessels or promote the release of vasodilating substances and cause delayed erythema, vascular permeability also increases and edema occurs; medium-wave UVB can also stimulate melanocytes, a large number of melanin color in the sun 2 to 3 days after the generation, so the skin gradually tanned. Long-wave ultraviolet light is 100 times more than medium-wave ultraviolet light, and easy to penetrate ordinary glass, but less irritating, can make the skin immediately erythema, after dozens of minutes can disappear, long-wave ultraviolet light can also increase the oxygen content of melanin and quickly cause pigmentation, but the duration is shorter. Visible light has little biological effect on the skin, but it is easy to stimulate the retina. Infrared light is invisible radiant heat and causes only temporary dilation of skin vessels due to thermal stimulation. Prevention Those who are sensitive to sunlight, especially in early summer when the skin is not yet tanned, should pay attention to prevent from strong sunlight by holding an umbrella or wearing a wide-brimmed hat and long-sleeved clothes, but sunlight can be reflected from the ground, water, desert or snow, which often cannot completely prevent sunburn. In order to gradually enhance the skin’s tolerance to sunlight, the exposure time can be gradually extended under not too strong sunlight, so that the skin gradually tans and strengthens the ability to resist light, but should be carefully exercised to prevent the occurrence of acute heliodermatitis. People whose skin is prone to sunburn but who have to work in the sun can apply shading agents, which have a temporary light-protective effect. Shading agent can be divided into physical and chemical: 1, physical shading agent There are zinc oxide, iron oxide, bismuth subcarbonate and titanium dioxide, etc., can block a variety of wavelengths of ultraviolet light, light-proof effect is good. The thicker the coating, the better the effect, but because of the impact on aesthetics, patients often do not like the application. 2, chemical sunscreens There are ellagic acid, benzyl salicylate or methyl salicylate, p-aminobenzoic acid and benzophenone, etc., with the appropriate substrate formulated into a sunscreen coated on exposed skin, can more or less prevent sun dermatitis. 3, sunscreen selection First of all, we must correctly identify the label of the sunscreen and its significance, PA refers to the classification of the UVA protection factor, while SPF refers to the UVB protection factor, the two do not have the significance of cross-reference. A single indicator does not indicate protection against all UVB rays in the sun. The zinc oxide and titanium dioxide contained in the shading agent have the effect of reflecting sunlight. The new sunscreen, some adding antioxidants such as vitamin A, C, E and green tea extract, etc., can enhance its light-protection effect. Of course, the strength of sunscreens is related to their sun protection factor, and SPF 30 sunscreens are 30 times more effective than the natural sun protection of normal skin. Despite the use of this shade, the skin will still have some tanning. 4, the application of sunscreen sunscreen effect and its actual application dose, water resistance performance is closely related. The general test method in the application amount is 2mg/cm2, when the sunscreen application amount is halved, its protection factor can be reduced by 50% to 60%. In the specific use of sunscreen products, should be selected according to the actual amount of UV exposure. Women who work indoors and housewives can use sunscreen with SPF10 and PA+ when they go out, while those who work outdoors and those who are active outdoors at noon are recommended to use sunscreen with about SPF20 and PA++, while those who are active under the scorching sun and when bathing in seawater should use sunscreen with good water resistance and about SPF30 and PA+++; sunscreen with super high SPF value is necessary for those who have photosensitivity. It is necessary for patients with photo allergy. When going out in summer, it is important to use not only UVB protection, but also UVA protection. Treatment Topical medications such as glyburide lotion, zinc cream, etc. In case of severe acute dermatitis, it is best to use diluted compound aluminum sulfate solution or wet compresses with cold buttermilk, which can make the patient comfortable. The corticosteroid configuration of the lotion, spray or cream can make the inflammation and pain reduced. 0.1% alcohol solution of anti-inflammatory pain can be applied, it is believed that anti-inflammatory pain can inhibit prostaglandin synthetase in the skin and can prevent the formation of prostaglandin E, thus preventing UVB from causing erythema. When the sunburn is severe, corticosteroids such as prednisone can be taken, and aspirin can make the pain less.