Emission of ammonia from human skin and its impact on indoor air quality

Abstract

Ammonia is one of the members of odor gases and is a possible source of odor to neighboring persons in indoor environment when emanating from human body surface. However, little has been known on the actual emission rate of ammonia from the skin surface. This study then aimed to determine influence of ammonia from human skin on the indoor air concentration levels. Authors practically measured emission flux of ammonia from human skin of 29 volunteers by originally-developed passive flux sampler - indophenol blue methodology. Ammonia was passively collected by a trapping filter of the sampler for 1 hour, extracted by borate solution with a mild shaking and then determined by spectrometry. The emission flux was then derived from collection amount of ammonia within 1hour and area of skin surface covered by the sampler. Using the emission flux data, indoor diffusion concentrations were estimated by Near-Field Far-Field zones model. The near field was set as a hemispherical space with 60 cm of radius (corresponding to the length of arms) and a person (odor source) was assumed as a point source. The results showed estimated near field concentration of ammonia, ranging from 42 – 529 ?g/m3 (mean: 52 ?g/m3) was too low to perceive the odor by neighboring persons in most cases. However, the emission flux of ammonia significantly increased, when the volunteers were exercising with sweating, and the mean near-field concentration became 1.7 times greater than those at rest. In the latter case, most of concentration levels were enough to perceive the slight odor of ammonia by neighboring persons. These results lead a conclusion that odor intensity of ammonia emanating from skin depends on physical and/or physiological conditions of a person in indoor environment.