Chemical and Oxidative Properties of Indoor PM: Discerning the Influence of Residential Characteristics
P. S. GANESH SUBRAMANIAN, Alice Oloo, Vinh Vo, Brenda Koester, Vishal Verma, Sheena E. Martenies, University of Illinois Urbana-Champaign
Abstract Number: 493
Working Group: Health-Related Aerosols
Abstract
Oxidative potential (OP) is an emerging metric, that quantifies the ability of particulate matter (PM) to induce oxidative stress in humans and cause adverse health outcomes. Although people spend the largest proportion of their time in residential environments, our understanding of exposure to PM constituents and its OP in this critical environment is limited. In this study, we collected PM samples from 22 homes in the Champaign-Urbana region (CUR), Illinois, and characterized their chemical composition and OP [using dithiothreitol (DTT) assay]. Residential characteristics were also obtained using questionnaires from each participant. The median concentrations of PM (PMC), water-soluble organic carbon (WSOC), and metals across the residential environments were 12.94, 1.34, and 0.32 μg/m3, respectively. The median OPv (volume-normalized OP) of residential PM was 185.90 pmol/(min.m3), which is comparable with values reported for ambient PM2.5 in CUR. Exploratory exposure assessment revealed significantly higher OP exposure in residential environments (> 7×) compared to ambient, due to a larger proportion of time spent indoors. Chemical constituents such as WSOC, and redox-active metals such as Cu and Mn were mainly driving OPv, aligning with past findings on ambient PM2.5. Univariate analysis revealed an increase in PMC and OPv with increasing window-opening frequency or decreasing floor area, indicating the effect of building characteristics on PM characteristics. The median PMC and OPv of residences using gas stoves were 72% and 42% higher than those using electric stoves, respectively. Similarly, scented candle usage also resulted in a 71% and 34% increase in the median PMC and OPv, respectively, signifying the importance of indoor-source characteristics in determining residential exposure to toxic PM. Collectively, these findings reveal that residential characteristics play a significant role in determining PM and OPv exposure indoors and emphasize the need for studies with larger cohort sizes to reliably estimate residential exposures as a function of building and source characteristics.