Chemical and Oxidative Properties of Indoor PM: Discerning the Influence of Typical Building and Source Characteristics

Oxidative potential (OP) is an emerging metric of PM-induced toxicity that has been linked to cardio-respiratory health outcomes in recent epidemiological studies. Although people spend almost two-thirds of their time in residential environments, their exposure to the OP of particulate matter (PM) in this critical environment is sparsely studied. Here, we quantify the OP (using dithiothreitol assay) and chemical composition of PM collected from diverse residential environments [22 homes in Champaign-Urbana Region (CUR), IL] and evaluate the effects of residential characteristics in discerning exposures to OP. The median OP of residential PM [185.90 pmol/(min m 3 )] was comparable with the values reported for ambient PM 2.5 in CUR. Both the particle mass concentrations (PMC) and OP consistently increased with decreasing floor area. The PMC and OP 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 PMC and OP, respectively, signifying the importance of indoor-origin PM in determining residential exposure to OP. Collectively, these findings emphasize the need for further investigations to reliably estimate residential exposures to toxic PM, as a function of building characteristics and source usage patterns.