American Association for Aerosol Research - Abstract Submission

AAAR 39th Annual Conference
October 18 - October 22, 2021

Virtual Conference

Abstract View


Humidity and the Uptake of a Model Organic Peroxide on Naturally Soiled Indoor Window Surfaces

MARC WEBB, Liyong Cui, Karsten Baumann, Jason Surratt, Glenn Morrison, Joanna Atkin, Barbara Turpin, UNC-Chapel Hill

     Abstract Number: 206
     Working Group: Indoor Aerosols

Abstract
Aqueous chemistry on wet aerosol surfaces significantly alters outdoor air composition. Likewise, aqueous chemistry on indoor material surfaces may alter indoor air composition. Surfaces play an important role in indoor air chemistry, where surface area-to-volume ratios are greater than 3 m2/m3, orders of magnitude greater than that of typical aqueous aerosols. Indoor material surfaces are soiled with organic and inorganic species from exposure to air pollution; soiling provides a condensed phase reservoir for partitioning of indoor gases , including water. Adsorbed water on indoor surfaces may enhance partitioning and enable aqueous surface chemistry of water-soluble organic gases (WSOGs), including organic peroxides. Here, the effect of relative humidity (RH) on the deposition velocity (vd) and reaction probability (γ) of a model organic peroxide to naturally soiled interior window surfaces was investigated.

Isoprene hydroxy hydroperoxide (ISOPOOH) was used because of the potential importance of organic peroxides to indoor air quality and chemistry. Glass was soiled in 3 local homes for 1+ years and the surface composition measured. The uptake of ISOPOOH by clean and soiled glass was measured under 5%, 55%, and 85% RH conditions using a novel indoor surface flow reactor coupled to a chemical ionization mass spectrometer (CIMS). Under humid conditions ISOPOOH was initially substantially (78%) depleted for soiled glass; in contrast only 24% removal was observed for clean glass. Under dry conditions, there was no significant enhancement of ISOPOOH uptake to soiled glass compared to clean glass. Steady-state vd and γ to soiled glass at 55% RH was 0.003-0.001 cm sec-1 and 3.3 x 10-7-6.0 x 10-8, respectively. The fate of the ISOPOOH and reversibility of uptake will be discussed. This work contributes parameters for indoor air quality and exposure modeling for indoor settings.