Effect of Ambient Humidity on the Transmission of UV/Visible Light through Model Human Epidermis

Abstract

Transmission of light through model human epidermal samples is investigated at four different wavelengths and at varying ambient humidity. Light from light emitting diodes (LEDs) is used for transmission measurements through the samples at a UVA wavelength of 365 nm, and visible wavelengths of 460 nm, 500 nm, and 595 nm. Ambient air-humidity is varied between 20% and 100%. Results show that for high ambient humidity, near 100%, transmission of light through the epidermis is higher than at low ambient humidity, 60% or lower. These results are explained with a simple model of epidermis as a turbid medium and the effect of adsorbed water in reducing light-scattering by refractive-index-matching. Biological implications of increased light-transmission through epidermis at high ambient humidity are discussed. KeywordsModel Human Epidermis, Model Skin, Effect of Humidity, Transmission of Light, Optical Properties of Epidermis

Increased incidence of chronic actinic dermatitis in relation to climate changes and air pollution during the past 15 years in Korea

“…Owens et al 22 demonstrated that higher humidity enhances the injurious effects of UV-A radiation in vitro. Farley et al 23 showed that a higher mean air humidity increases light transmission through the hydrated stratum corneum and induces greater damage from UV radiation than does a lower mean air humidity. Furthermore, in the Korean peninsula, the mean air humidity is highest under the influence of typhoons in summer season.…”