AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Using Aerosol Principles to Advance Exposure Science: The Effect of Humidity on the Uptake of Water-Soluble Gases on Authentic Indoor Surfaces
MARC WEBB, Liyong Cui, Joanna Atkin, Glenn Morrison, Jason Surratt, Barbara Turpin, UNC-Chapel Hill
Abstract Number: 214 Working Group: The Air We Breathe: Indoor Aerosol Sources and Chemistry
Abstract Surfaces play an important role in indoor chemistry, where surface area-to-volume ratios are greater than 3 m2/m3, orders of magnitude greater than typical of ambient aerosols. The surfaces of materials found in indoor environments are known to be soiled with films composed of oxidized organic compounds that present a condensed phase for partitioning of semi-volatile organic compounds (SVOCs), many of which are considered water-soluble. Even though “dampness” is a substantial issue in buildings, little is known about the hygroscopicity of indoor surfaces, the adsorption/absorption of water-soluble gases, the effects of liquid water on indoor surface chemistry, and the subsequent effects of that chemistry on exposure. However, even a 5 nm water film on indoor surfaces (assuming 20 m2/m3 of surface in a 300-m3 home) will provide more than 1000 times the volume of liquid water as is found in aerosols outdoors. Since the resulting aqueous solutions will be highly concentrated, aqueous surface chemistry on authentic indoor surfaces may mimic aqueous aerosol chemistry.
We provide results to date on controlled experiments with fresh and authentic indoor surfaces—painted wallboard and window panels exposed to indoor air in real occupied homes for 4-8 months. A custom parallel plate flow reactor designed to hold indoor surface materials and a high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) are used to monitor uptake of acetic acid, IEPOX, ISOPOOH and hydrogen peroxide on indoor surfaces at 5%, 50% and 90% RH. The difference in RH entering and exiting the flow reactor allows quantification of water content of the indoor material at each RH. Surface film composition of glass slides from each home will be characterized by ultra-high resolution electrospray ionization QTOF-MS. This work is designed to provide quantitative constraints for indoor modeling that will ultimately improve our understanding of the impact of “dampness” on indoor exposures.