Physical Causes: Heat, Cold, and Other Atmospheric Factors

Abstract

Several ambient conditions or physical work-related exposures can induce skin changes. These may either represent normal reactions to an “abnormal” level of an exogenous factor, e.g., high or low temperature, or abnormal reactions to conditions which are normally compensated by skin homoeostasis and thus generally tolerated. Heat induces skin damage directly in terms of thermal or electrical burns of various degrees and extent, requiring adequate emergency treatment. However, heat may be applied to skin also via infra-red radiation or prolonged direct exposure to moderate heat, causing Erythema ab igne. Ambient heat may cause sweat retention in different layers of the eccrine sweat glands and thereby miliaria. Similar conditions predispose to intertrigo, a macerated, Erythematous eruption in body folds, especially with excessive sweating and in obese persons. Cold has considerable, potentially life-threatening systemic effects (exposure) and can cause frostbite. Moderate cold may cause an abnormal reaction in the susceptible in terms of perniosis (chilblains) of exposed acral body regions, mostly the fingers. Prolonged wetness, usually of the feet and lower legs, especially if combined with low temperature, can cause “immersion foot” as a nonfreezing cold injury. As another nonfreezing injury, and with mechanical effects of rowing contributing to etiology, “pulling boat hands” have been described. In addition to temperature, ambient humidity may have some adverse effect on skin, for instance, in terms of low outdoor humidity (typically less than 10 mg/l) contributing to skin irritation and eventually irritant contact dermatitis. Similarly, low indoor humidity, e.g., in clean-rooms, has been found to cause highly pruritic, if clinically largely inconspicuous skin eruptions in a large share of exposed workers. Symptoms may be aggravated by, e.g., fine, irritating particles.