Abstract
People influence indoor air chemistry through their chemical emissions via breath and skin. Previous studies showed that direct measurement of total OH reactivity of human emissions matched that calculated from parallel measurements of volatile organic compounds (VOCs) from breath, skin, and the whole body. In this study, we determined, with direct measurements from two independent groups of four adult volunteers, the effect of indoor temperature and humidity, clothing coverage (amount of exposed skin), and indoor ozone concentration on the total OH reactivity of gaseous human emissions. The results show that the measured concentrations of VOCs and ammonia adequately account for the measured total OH reactivity. The total OH reactivity of human emissions was primarily affected by ozone reactions with organic skin-oil constituents and increased with exposed skin surface, higher temperature, and higher humidity. Humans emitted a comparable total mixing ratio of VOCs and ammonia at elevated temperature-low humidity and elevated temperature-high humidity, with relatively low diversity in chemical classes. In contrast, the total OH reactivity increased with higher temperature and higher humidity, with a larger diversity in chemical classes compared to the total mixing ratio. Ozone present, carbonyl compounds were the dominant reactive compounds in all of the reported conditions.
Highlights
On average, we spend 85−90% of our time indoors,[1,2] that is, at home, in offices, and schools
We showed that the reactive volatile organic compounds (VOCs) budget was closed, that when O3 was present, “OH reactivity approximately doubled” with the increase due to unsaturated secondary products of O3-skin-oil chemistry (57%), and that no significant difference was observed among different age groups.[34]
In this study, using results from a different set of experiments, we examine the effects of indoor O3 concentration, clothing, temperature, and relative humidity on the total OH reactivity of whole body emissions from experiments involving two different groups of adult volunteers
Summary
We spend 85−90% of our time indoors,[1,2] that is, at home, in offices, and schools.
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