Physiological and Subjective Responses to Low Relative Humidity

Abstract

In order to investigate the influence of low relative humidity, we measured saccharin clearance time (SCT), frequency of blinking, heart rate (HR), blood pressure, hydration state of skin, transepidermal water loss (TEWL), recovery sebum level and skin temperature as physiological responses. We asked subjects to judge thermal, dryness and comfort sensations as subjective responses using a rating scale. Sixteen non-smoking healthy male students were selected. The pre-room conditions were maintained at an air temperature (Ta) of 25 degrees C and a relative humidity (RH) of 50%. The test room conditions were adjusted to provide a Ta of 25 degrees C and RH levels of 10%, 30% and 50%.RH had no effect on the activity of the sebaceous gland and on cardiovascular reactions like blood pressure and HR. However, it was obvious that low RH affects SCT, the dryness of the ocular mucosa and the stratum corneum of the skin and causes a decrease in mean skin temperature. Under 30% RH, the eyes and skin become dry, and under 10% RH the nasal mucous membrane becomes dry as well as the eyes and skin, and the mean skin temperature decreases. These findings suggested that to avoid dryness of the eyes and skin, it is necessary to maintain an RH greater than 30%, and to avoid dryness of the nasal mucous membrane, it is necessary to maintain an RH greater than 10%. Subjects felt cold immediately after a change in RH while they had only a slight perception of dryness at the change of humidity.

Higher Prevalence of Dry Symptoms in Skin, Eyes, Nose and Throat among Workers in Clean Rooms with Moderate Humidity

“…There are relatively more studies on the effects of RH in the 5% to 30% range, and they have generally found skin effects as well, especially in people with pre-existing atopic eczema [12][13][14][15][16][17][18] . In particular, Wyon 19) and Nordstrom et al 20) described an improvement of dry symptoms and sick building syndrome after humidification, and Reinikainen et al 21) reported a decrease in symptoms of allergic reactions in office workers subsequent to an elevation in RH from 20% to 40% in the working environment.…”

Update of the scientific evidence for specifying lower limit relative humidity levels for comfort, health, and indoor environmental quality in occupied spaces (RP-1630)

“…Subjects in the study by Laviana et al (1988) indicated no significant changes in eye comfort for healthy eyes without contacts between 10% and 30% RH. In the study by Sunwoo et al (2006a) blink frequency was higher at 30% RH and 10% RH than it was at 50% RH, but they did not address whether visual acuity was affected by environmental conditions. Wyon et al (2006) conducted a thorough study using a mucus ferning test which indicated eyes were drier at 5% and 15% RH compared to 25% and 35% RH at room temperature, suggesting that RH greater than 15% is preferable.…”

“…The focus of the literature review was to determine the effects of low humidity on healthy eyes (Laviana et al, 1988;McCulley et al, 2006;Sunwoo et al, 2006a;Wyon et al, 2006;Arciniega et al, 2011;Abusharha and Pearce, 2013), although several papers were located that addressed the effects of humidity on subjects with dry eyes (Mathers and Daley, 1996;Borchman et al, 2009;Arciniega et al, 2011;Galor et al, 2011;Tomlinson et al, 2013). In addition, the effects of contact lenses were not the main focus of this study, but have been studied by several researchers (Laviana et al, 1988;Tsutsumi and Tanabe, 2002).…”

Oral Intake of Glucosylceramide Improves Relatively Higher Level of Transepidermal Water Loss in Mice and Healthy Human Subjects

“…Decrease of barrier function is associated with diseases such as atopic dermatitis (AD), [1][2][3][4] which is characterized by skin dryness and intense itching. Impairment of skin barrier function may also be caused by sudden change of the weather 5,6) or contact with chemical agents such as cleansers. 7,8) Severe itching may reduce the quality of life (QOL) through induction of sleep disorders.…”