Cutaneous burn at an elevated ambient air temperature

The risk of cutaneous burn is usually assessed by comparing the temperatures measured at external surfaces when the equipment is operated as intended under ambient conditions specified by the manufacturer, with the thresholds established by experimental results in delicate laboratory environments. In the real world ambient air temperature varies with geographical location, the time of the year and so on, over which equipment manufacturers only have little control. It had been an industry practice that the user will be provided with information about the maximum recommended ambient air temperature at which the equipment can operate satisfactorily without compromising its functionality, operability as well as safety. An interest arose as to how these burn thresholds would be seamlessly applied to the real world hot surfaces. It has been the author's opinion that human body temperature is nearly independent of change in ambient air temperature while surface temperatures of any equipment, with or without thermal control, would generally depend on the ambient temperature, in other words, surface temperature will vary with ambient and yet the temperature difference between the surface and skin will vary, too. This paper will first discuss how human body regulates its temperature and then how higher ambient air temperature can weaken the ability of equipment to dissipate heat. The author's hypothesis will be demonstrated by several comparative tests at different ambient temperatures.