AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Characterizing VOC Emissions from Human Occupants in a University Classroom
XIAOCHEN TANG, Pawel Misztal, Allen H. Goldstein, William Nazaroff, University of California, Berkeley
Abstract Number: 596 Working Group: Indoor Aerosols
Abstract Little is known about the chemical emissions associated with human occupants, even though this source can make important contributions to indoor airborne particles and volatile organic compounds (VOCs).
In this work, we characterize gaseous occupant-related emissions in a university classroom by measuring real-time concentrations and calculating per person emission rates for hundreds of VOCs using a proton transfer reaction time-of-flight mass spectrometer (PTR-ToF-MS). Among the more than 300 ions detected in 19 class sessions, more than 80% were in the range m/z = 30-150. Among the ions detected are those with well-known human emissions, such as isoprene, acetone, and acetic acid. For each ion, we assign a proposed chemical formula and/or structure when reporting the indoor and supply air concentration and the emission rate (ug h$^(-1) person$^(-1)). Remarkably, these ions with low to moderate m/z ratios only comprise about half of the total emitted mass. The other half was dominated by three organic cyclic siloxanes: D4 (octamethylcyclotetrasiloxane), D5 (decamethylcyclopentasiloxane) and D6 (dodecamethylcyclohexasiloxane). The inferred emission rate of D5 is one to two orders of magnitude greater than that of D4 and D6. The emissions of D5 and D6 show relatively strong correlation (r>0.7) with each other, suggesting similar sources, which we believe to be personal care products used by classroom occupants. This study represents the first broad characterization of VOCs emitted from human occupants using the highly sensitive PTR-ToF-MS over the mass range m/z 30-500. The research findings will broaden knowledge about indoor air chemistry and advance understanding of the relationship between humans and their everyday environment.