Skin burns are caused by heat through three physical effects, namely radiation, convection, and conduction. (1) radiation of heat: is a weaker thermal injury-causing factor. Because of this normal situation, only part of the infrared rays are absorbed by the skin, most of them are refracted and do not produce burns. When the heat source > 1000 ℃, such as the temperature of the arc sparks up to 4000 ℃ or more, can be in 0.1 seconds or less on the skin wrapped in thermal injury, is the most common clinical radiation burns. Another common radiation burn is “sunburn”, which is caused by ultraviolet radiation from the sun, and is actually an inflammatory response to increased skin temperature. Radiation heat generally causes only superficial burns. (2) heat convection: the severity of heat convection burns depends mainly on the dryness and humidity of the air. In dry air at 100 ℃, the skin is heated to 4.2 J (Joule) / c ㎡. 42 J / c ㎡ at 400 ℃. If it is 100 ℃ steam, the skin can be heated to 50J / c square meters. Therefore, steam heat convection at lower temperatures can also produce serious burns. (3) Heat conduction: It is the main form of thermal injury caused by direct contact of hot solids and liquids with the skin through heat conduction. Clinical thermal injuries rarely exist in a single pattern, often radiation, convection and conduction exist simultaneously. In burns caused by conduction, the temperature rise in the tissue is at least 1000 times higher than that caused by radiation or convection.