Effects of ionized water nanodroplets (mist) released from an air-conditioner on the biophysical and biomechanical properties of skin in low humidity rooms

Abstract

Due to the construction of airtight housing, which has been developed to conserve energy in order to prevent global warming, and heat island phenomena caused by urbanization, it has become commonplace for families living in modern homes in Japan to own one or more air-conditioners. At offices, a lot of electronic equipment releases heat all day long. It is not uncommon for relative humidity levels to fall below 20% in air-conditioned rooms, which can cause the occupants’ facial skin to become dry. Severe skin drying can occur in people with reduced skin barrier function, e.g., those with atopic dermatitis, middle-aged women, the elderly, etc. Although conventional humidifiers have been used to moderate skin dryness in air-conditioned rooms, some problems have arisen, such as thermal dissatisfaction caused by increases in humidity during summer; dew condensation on windows during winter; the growth of bacteria in water for humidification; and debate regarding the optimal placement of air-conditioning units in terms of effectiveness and safety, etc. In recent years, the generation of nanosized particles and ions using electrospray techniques has been successfully employed to create indoor water vapor via the Peltier effect; i.e., the “mist” described in the present paper. In addition, home appliance and cosmetic companies have started to incorporate mist generators in health/beauty equipment. The nanosized droplets emitted from such equipment are expected to penetrate into the stratum corneum and improve its moisture content. However, little data about the biophysical and physiological effects of such droplets have been reported. A new type of air-conditioner containing a mist generator has recently been tested during summer and winter to examine whether it could contribute to moisturizing and softening skin without increasing ambient humidity. The present paper reviews recent studies regarding the effects of mist on the biophysical and biomechanical properties of skin.