IVL Swedish Environmental Research Institute

People influence indoor air chemistry through theirchemical emissions via breath and skin. Previous studies showed thatdirect measurement of total OH reactivity of human emissionsmatched that calculated from parallel measurements of volatile organiccompounds (VOCs) from breath, skin, and the whole body.

In thisstudy, we determined, with direct measurements from twoindependent groups of four adult volunteers, the effect of indoortemperature and humidity, clothing coverage (amount of exposedskin), and indoor ozone concentration on the total OH reactivity ofgaseous human emissions.

The results show that the measuredconcentrations of VOCs and ammonia adequately account for themeasured total OH reactivity. The total OH reactivity of humanemissions was primarily affected by ozone reactions with organic skinoilconstituents and increased with exposed skin surface, higher temperature, and higher humidity. Humans emitted a comparabletotal mixing ratio of VOCs and ammonia at elevated temperature-low humidity and elevated temperature-high humidity, withrelatively low diversity in chemical classes.

In contrast, the total OH reactivity increased with higher temperature and higherhumidity, with a larger diversity in chemical classes compared to the total mixing ratio. Ozone present, carbonyl compounds were thedominant reactive compounds in all of the reported conditions.