Repeated or prolonged exposure to a heater is a common cause of this condition in elderly individuals. Occupational hazards of silversmiths and jewellers (face exposed to heat), bakers and chefs (arms, face) Resting a laptop computer on the thigh (laptop computer-induced erythema ab igne). In a 2012 review, Riahi and Cohen describe the characteristics of laptop computer-induced erythema ab igne.[5] Temperatures between 43-47 °C can cause this skin condition; modern laptops can generate temperatures in this range.