AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
Abstract View
Aerosol-Phase Effects of Occupants in a Wintertime Classroom
ANITA AVERY, Michael Waring, Peter DeCarlo, Drexel University
Abstract Number: 480 Working Group: Indoor Aerosols
Abstract Humans can impact the composition of indoor air via heterogeneous reactions of gas-phase oxidants with skin constituents on a person, or skin that has been shed (desquamation), as well as by direct emissions from people themselves (bioeffluents) and the personal care products they use. However, separating the influence of the many emissions and oxidation products from those of outdoor influence has been a challenge. This work aims to identify and quantify the aerosol-phase impact of human occupants on the indoor environment. Real-time indoor and outdoor aerosols were measured simultaneously at high time resolution with a high-resolution time of flight aerosol mass spectrometer (HR-ToF-AMS) in a classroom with regular student occupants in Philadelphia. In this way, the influence of outdoor aerosols was assessed separately from that of emissions from occupants. Individual hydrocarbon mass fragments consistent with squalene fragmentation of C5H9+, C6H9+, and C7H9+ were significantly enhanced with room occupancy as determined by high indoor CO2 concentrations. Additionally, fragment C8H13O+, which is associated with the oxidation product of squalene and ozone of 4-MHO, increased by 22% in high versus low CO2 events. Fragment emission rates were quantified by relation to number of occupants. Ozone outdoors was observed in a typical diurnal pattern, while indoor ozone varied very little over time, resulting in a large calculated beta value during occupied times compared with unoccupied times. While these fragments contributed little to the overall aerosol mass in the classroom, they represented an exposure route for organic aerosol in poorly ventilated and/or highly occupied classrooms.