Humans generate high concentrations of hydroxyl (OH) radicals when exposed to ozone

In this study, we quantified for the first time the OH radicals generated via ozonolysis of alkene compounds emitted by humans indoors. To achieve this, we used direct measurements of VOCs and OH reactivity (inverse of OH lifetime) from three different groups of four adult subjects occupying a controlled environmental chamber. The subjects were exposed to either clean air or air containing 35 ppb of O₃. Measured data were input into a model describing the chemistry associated with skin emissions, and results were input into a computational fluid dynamic model that estimated the spatial distribution of OH radicals and OH reactivity inside the room. Our findings show that human beings, in the presence of O₃, are capable of generating substantial concentrations of OH radicals indoors. The spatial concentration gradient depends on the flow field, O₃ entry point, and occupant location.