Human breath emissions of VOCs

The medical community has long recognized that humans exhale volatile organ ic compounds (VOCs). Several studies have quantified emissions of VOCs from human breath, with values ranging widely due to variation between and with in individuals. The authors have measured human breath concentrations of is oprene and pentane. The major VOCs in the breath of healthy individuals are isoprene (12-580 ppb), acetone (1.2-1,880 ppb), ethanol (13-1,000 ppb), me thanol (160-2,000 ppb) and other alcohols. In this study, we give a brief s ummary of VOC measurements in human breath and discuss their implications f or indoor concentrations of these compounds, their contributions to regiona l and global emissions budgets, and potential ambient air sampling artifact s. Though human breath emissions are a negligible source of VOCs on regiona l and global scales (less than 4% and 0.3%, respectively), simple box model calculations indicate that they may become an important (and sometimes maj or) indoor source of VOCs under crowded conditions. Human breath emissions are generally not taken into account in indoor air studies, and results fro m this study suggest that they should be.