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Moala Bannavti

Environmental Sciences Seminar

DATE/TIME: Friday, April 7, 2023, 2:30 pm

Moala Bannavti
University of Iowa

Impact of Indoor Material PCB Emissions on Concentrations for Airborne Remediation Prioritization

There are few regulations that require the remediation of PCBs in buildings. Currently, federal laws on indoor PCBs only regulate building material concentrations. Yet, airborne exposure to PCBs has increasingly become a concern. To reconcile federal regulation of material PCB concentrations with airborne PCB advisories there is a need to characterize PCB emissions and congener distributions. We measured PCB emissions of the same set of wood panel walls, tile flooring, and tile flooring overlaid with carpet using polyurethane foam emissions samplers. Emissions of the sum of 209 congeners (excluding analytical standards) ranged from 4.61 x 103 from wood panel to 2.98 x 104 ng m-2day-1 from vinyl tile. Emissions varied from material to material within a single building, even in the same room. Bare vinyl tile (> 37%) and intra-room tile with carpet overlay (> 8%) installed during the peak of PCB production were significant influences on the congener distribution of PCBs observed in the room air before and after hexane wiping. We observed statistically similar congener distributions between material PCB emissions profiles and room PCB air profiles (cos θ > .97). There was a statistically even distribution of surface PCBs on large-area materials within a room (104 – 105 ng m-2). Hexane wiping reduced surface PCBs by 61%, however, a repeated emissions deployment post-wiping showed that this remediation method was temporary. The material concentrations ranged from 204.91 to 1.20 x 104 ng g-1. A mass balance model of two rooms showed the PCB mass from gross post-wipe emissions of measured materials fully accounted for the mass present in room air. If the rooms had a no PCBs in the air initially, and the concentration flowing into the room from outside was negligible, it would take about 12 hours for emissions from floors and walls to reach observed air concentrations (21.79 – 133.90 ng m-3). States like Vermont are beginning to set mandatory action levels for airborne PCBs indoors, especially in schools (30 – 90 ng m-3). Our results support the hypothesis that direct material emissions are a better indication of airborne PCB levels than material concentrations of room air considered too dangerous fors children’s exposure by the state of Vermont. These results indicate emissions of indoor building materials are relevant in both magnitude and congener distribution and can serve as an alternate criterion for creating more efficient prioritization of material or room PCB remediation.

Seminar Host:
Lisa Rodenburg
Department of Environmental Sciences, Rutgers University