THERMAL CONDITIONS WHICH CAUSE SKIN BURNS.

After describing the structure of human skin, it is pointed out that clinically there are two important depths of burn, those that involve the partial thickness of the skin and those in which the entire depth of the skin (and possibly underlying tissues) has been destroyed. Partial skin thickness burns, although painful, will heal from surviving epithelial elements in skin deep to the burn. Full thickness burns can only heal by ingrowth of new epithelium from the wound edge; in man this process is slow and frequently unsatisfactory; consequently such burns, if more than a few square centimetres in area, are treated by skin grafting. Standard curves showing minimum times and temperatures required to produce various types of burn are shown. Such curves can be used to determine safe surface temperatures of heated objects that might accidentally come into contact with skin. However, it is to be remembered that the limit of these curves is skin damage; in some situations - for example, where hot objects have to be handled - it might be wiser to choose conditions that do not cause discomfort. The authors investigated this by using human subjects; from these experiments a further curve was produced which was found to parallel the curves of conditions causing actual skin damage. Small thermocouples were used to monitor the temperature between the skin and the hot handle (a copper pipe through which thermostatically controlled water was circulated); it was found that most subjects reported discomfort when the skin/handle interface reached 43 degree C. It seemed likely that preferred bath and shower temperatures might also provide information concerning the temperature that skin could tolerate without discomfort. The average bath temperature of a group of 20 subjects was 40. 5 degree C; the range was from 36 degree C to 42. 5 degree C.