Dissertation
Emission characterization and criteria for remediation of airborne Polychlorinated Biphenyls in a school and a university building
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Spring 2023
DOI: 10.25820/etd.007002
Abstract
Polychlorinated biphenyls (PCBs) are a group of 209 human-made persistent organic pollutants. Inhaled exposure to PCBs has been linked to cancer, hormone disfunction, and cognitive learning disorders regardless of age or sex. PCB mixtures were intentionally produced in the United States as Aroclors by Monsanto from the 1930s to late 1970s when it was outlawed by the Toxic Substance Control Act (TSCA). Increased usage of PCBs in building materials directly coincides with the rise of public construction from the 1950s to 1980. An estimated 55,000 US public and private schools are contaminated with Aroclor PCBs. Additionally, schools may be contaminated with modern PCBs that are inadvertently manufactured in colorant production processes. These colorants are added to inks, paints, and other brightly colored items used in schools. PCB remediation in schools is often expensive and is not airborne-focused, despite evidence that inhalation is an equal or greater exposure route than diet. The work of this thesis is to understand the emission characterization of airborne PCBs indoors and diverse stakeholder perspectives on remediation in hopes of improving its cost efficiency and equity. This work seeks to observe if a room can serve as a PCB micro-environment within a building, and furthermore, if materials within a room can dictate the magnitude and distribution patterns of PCB congeners. I conducted three major studies to meet these goals.
First, I examined the differences in airborne PCB concentration and congener distribution from room-to-room in a school building. I deployed polyurethane foam passive air samplers (PUF-PAS) in nine rooms and one outdoor location (n = 3 each) in Columbus Secondary School. Airborne PCB concentrations varied significantly from room-to-room (1.5 – 36 ng m-3). Rooms constructed or renovated before the TSCA (1977), had higher concentrations than those built after. Cosine theta analysis, positive matrix factorization and principal component analysis were used to observe differences in PCB congener distribution which also varied from room-to-room (cosine theta > 0.9). Most room air profiles were dominated by a mixture of Aroclor 1254 and 1016. Nevertheless, in the practice gym non-Aroclor PCBs were a significant source (~30%). Second, I identified airborne PCB emissions from commonly used, large surface area, indoor materials. I sampled emissions directly, using polyurethane foam passive emissions samplers (PUF-PES) in the University of Iowa’s Institute of Rural Environmental Health office building. Measurements were taken before and after removing surface PCBs via hexane wiping the flooring (tile with carpet overlay) and wood panel walling from two rooms, and hallway tile outside those rooms. Surface PCB removal significantly reduces emissions across all measured materials (p-value = 1.2 x 10-4). The difference before and after wiping the flooring (n=6) averaged 6,187 ng m-2d-1, wood panel (n=6) averaged 3,832 ng m-2d-1, and tile (n=3) averaged 11,841 ng m-2d-1. These results indicate a removable PCB surface layer is a distinct emissions source. Most of the 209 PCB congeners were significantly reduced by hexane wiping (59%). Using a mass balance simulation, I found emissions from flooring and walling fully accounted for the mass of PCBs in the room air.
Finally, I investigated which forms of science communication aid stakeholders in making decisions about PCB remediation of school air in the United States. I conducted a comprehensive review of studies specific to airborne PCB remediation in schools. Nine academic publications met the inclusion criteria. The review uncovered the need for all stakeholder groups to further investigate the influence of cost, legal regulation, and effectiveness of remediation practices on the state airborne PCB contamination in schools. To advance the exploration of these themes I held interviews with US Environmental Protection Agency personnel, engineering consultants, and a parent-teacher community group leader. Stakeholders use various forms of science communication to make decisions on airborne PCB remediation in schools including rigorous peer-reviewed journal articles and easily digestible, short presentations.
Throughout my dissertation work I participated in community-centered report back such as specialized lectures and a press release. The research presented in this dissertation advances stakeholder understanding of the sources and distribution of PCBs in schools and the predictive relationship between material emissions and air concentration indoors.
Details
- Title: Subtitle
- Emission characterization and criteria for remediation of airborne Polychlorinated Biphenyls in a school and a university building
- Creators
- Moala Keshei Bannavti
- Contributors
- Keri C Hornbuckle (Advisor)Craig L Just (Advisor)Rachel F Marek (Committee Member)Corey D Markfort (Committee Member)Brandi Janssen (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Civil and Environmental Engineering
- Date degree season
- Spring 2023
- DOI
- 10.25820/etd.007002
- Publisher
- University of Iowa
- Number of pages
- xix,153 pages
- Copyright
- Copyright 2023 Moala Keshei Bannavti
- Grants
- Language
- English
- Date submitted
- 04/25/2023
- Date approved
- 06/30/2023
- Description illustrations
- illustrations, tables, graphs
- Description bibliographic
- Includes bibliographical references (pages 143-153).
- Public Abstract (ETD)
- Polychlorinated biphenyls (PCBs), a group of 209 toxic chemicals, are found in school air across the United States. Exposure to inhaled PCBs in children has been linked to diabetes, respiratory ailments, thyroid complications, and disruption in brain development. However, some student populations are at a greater risk to encounter the negative ramifications of PCB exposure. Schools in lower-income communities have older facilities and often cannot afford currently advised remediation tactics like demolition, abatement, and mitigation. This inequity motivates me to better understand airborne PCB characterization indoors such as room-to-room differences, emission sources, and stakeholder perspectives on removal. I evaluated schoolrooms looking for differences in the total amount and pattern of airborne PCBs. I found that total amount and pattern of airborne PCBs vary from room-to-room in a single school building depending on the construction date and whether the emission sources are historic or modern. Prior studies failed to identify important emission sources and analyze them for all 209 types of PCBs. My studies confirmed that indoor floors (tile) and walls (wood) emit PCBs. These materials also have a removable surface layer of PCBs that contribute to room air concentrations. I conducted a comprehensive review of studies focused on the legal requirements of removing PCBs from school air and interviewed other professionals about their thoughts on whether these laws are effective. Though it is known that airborne PCBs in schools are not specifically regulated by the US Environmental Protection Agency, stakeholders agree with putting in place actionable limits. However existing state action levels may still lend themselves to inequity as they are currently written.
- Academic Unit
- Civil and Environmental Engineering
- Record Identifier
- 9984425312602771
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