AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Outside-In and Other Sources of Aerosols in the Indoor Environment
PETER DECARLO, Anita Avery, Erin Katz, Michael Waring, Marina Vance, Delphine K. Farmer, Drexel University
Abstract Number: 594 Working Group: The Air We Breathe: Indoor Aerosol Sources and Chemistry
Abstract Combining high time resolution indoor and outdoor measurements of particle composition by aerosol mass spectrometry from both studies performed in a university classroom, and the “HOMEChem” (House Observations of Microbial and Environmental Chemistry) project, we investigate the various sources and processes which contribute to indoor aerosols. For both the classroom and HOMEChem project, indoor particle mass concentrations are typically lower than outdoor concentrations in the absence of large indoor sources (e.g. cooking activities). Compositional changes for outdoor-to-indoor transported aerosol is observed and can be linked to changes in relative humidity (RH) and temperature (T) gradients between the outdoor and indoor environments (e.g. particle nitrate volatilization) when indoor T exceeds outdoor T. Additionally, unique indoor sources can be identified from residual cigarette smoke, human occupants, cooking, and cleaning activities. Residual cigarette smoke contribution to indoor aerosol was identified in a non-smoking building and contributed up to 30% of the indoor aerosol mass during warmer months when air conditioning (AC) was employed. During months when the building air supply was heated this component was not identified, and this difference is attributed to residual smoke chemical species partitioning to the liquid water phase of indoor aerosols present in summer (with AC), but not in winter. Human occupant contributions to secondary organic aerosol mass was identified during periods of high occupancy (elevated CO2) and enhanced indoor ozone loss in the classroom studies. Cleaning activities during HOMEChem also showed chemical changes to indoor aerosol composition, although mass enhancement was small. Finally cooking activities during HOMEChem showed the largest increases in indoor particle mass loadings and greatly exceeded outdoor levels. A significant fraction of this mass was chemically similar to cooking oils. The relative contribution of these various sources will be discussed.