Skin temperature during sunbathing--relevance for skin cancer.

It has been found that exposure to heat and infrared radiation (IR) can be carcinogenic, and that a combination of ultraviolet radiation (UVR) and IR possibly amplifies carcinogenesis. To investigate how the skin temperature is affected by sunbathing, we measured the skin temperature on 20 healthy volunteers over 6 days' sun holiday in Egypt. Temperatures were measured with an infrared thermometer gun at 8 skin sites on the volunteers while they were indoors in the morning and when sunbathing during the day. Skin temperatures were higher during sunbathing (33.5 °C ± 2.1 °C) (mean ± SD) than when indoors in the morning (32.6 °C ± 1.4 °C) (mean ± SD) (P < 0.0001). The average skin temperature for men was higher than for women by 0.40 °C in the morning (P = 0.02) and by 0.44 °C during sunbathing (P < 0.0001). Our results show that sunbathing has an impact on skin temperature, which possibly by activation of the heat shock response, is likely to contribute to the immediate and delayed effects of UV in a way that has to be found out in future studies.