Sorption of semi-volatile organic compounds to dust and other surfaces in indoor environments

Semi-volatile organic compounds (SVOCs) are ubiquitous in indoor environments. Because they partition strongly to dust other surfaces in the indoor environments, most SVOCs persist for years after the source is removed. Biomonitoring data based on blood and urine testing suggested the universal and significant human exposure to SVOCs, which may result in serious adverse health effects. However, because of the poor understanding of their transfer process from sources to indoor surfaces, significant uncertainties exist for the estimation of exposure to SVOCs through various pathways and effective strategies to limit such exposure remains hamstrung. The goal of this dissertation is to explicitly elucidate the sorption of important and emerging SVOCs to dust and other surfaces in the indoor environments. The specific research objectives are to 1) investigate the emission, sorption, and fate of phthalates in a residential test house; 2) characterize the direct transfer of SVOCs from sources to settled dust through systematic chamber study; and 3) measure SVOC levels in heating, ventilation, and air conditioning (HVAC) filter dust of U.S. lowincome homes and investigate their association with concentrations in settled dust, seasons, building characteristics, and childhood asthma. Strong sorption of phthalates was observed on interior surfaces, including dust, dish plates, windows, mirrors, fabric cloth, and wood, in a residential test house. In addition, when dust is in contact with the PVC floorings, equilibrium dust concentrations of phthalates are orders of magnitude higher than typical dust concentrations reported in the literature. And we found that the equilibrium concentrations of phthalates in dust can be predicted with the concentrations of phthalates within the gas layer in adjacent with the flooring materials. Finally, the results suggest that HVAC filter dust is a useful sampling media to monitor indoor SVOC concentrations with high sensitivity. When using settled dust, in addition to considering seasonal influences, it is very important to know the sampling location because the types and levels of SVOCs might be related to the local materials.