The impact of ambient humidity on healthy and diseased skin

Background: Temperature and ultraviolet radiation levels are known to have an impact on the skin’s health and function. Several studies have examined the role of another variable climatic factor humidity on healthy and diseased skin in human and mouse subjects, with varying results. Methods: An online literature search using key words was based around ambient relative humidity and its impact on skin health and function. Results: Murine studies determine that low humidity causes a number of changes in the skin, including the impairment of the desquamation process, while studies in humans demonstrate changes in transepidermal water loss values (a measure of the integrity of the skins barrier function), water content in the stratum corneum, skin elasticity and roughness parameters. Further epidemiological studies indicate an association between common dermatoses and ambient humidity, while several studies support the hypothesis that changes in humidity levels can induce or exacerbate dry skin disorders. Conclusion: Evidence suggests that humidity, and changes therein, can have an impact on a range of parameters involved in skin health. Further studies examining the effect of humidity on diseased skin and the associated biological mechanisms could provide evidence to support new treatment regimens for patients, helping to alleviate the burden of dry skin associated with many common skin disorders.