Date of Award:

5-2014

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Civil and Environmental Engineering

Committee Chair(s)

William J. Doucette

Committee

William J. Doucette

Committee

R. Ryan Dupont

Committee

Erik Dettenmaier

Abstract

Adults living in North America spend an estimated 80-90% of their time indoors where they can be exposed to a wide range of volatile organic chemicals (VOCs) found in home construction materials and consumer products (e.g. molded plastics, adhesives, cleaning products, paints, etc.). Some of these VOCs are known to be harmful if exposure concentrations are high or occur over a long period of time. Vapor intrusion (VI), the process by which VOCs in the soil or groundwater migrate to indoor air from a contaminated site, can also contaminate indoor air. Since remediation activities to prevent or stop VI are often very expensive, it is important to determine if the source of indoor air VOCs is internal or external.

The focus of this study was twofold. First to show that consumer products can have a significant effect on VOC concentration within indoor air and that screening level calculations can be made using a products emission rate to estimate the potential effects of a product on indoor air quality. Second to suggest a simple, cost-effective and sustainable approach to sampling indoor air VOC concentrations using plant leaves as samplers.

A full-scale house level study, monitoring air concentrations over time with consumer products acting as a source of VOCs in indoor air, was performed to determine if VOC concentrations could reach levels that can confound VI studies or pose a health risk. The full-scale house level study was used along with two other studies, a small-scale headspace study and a bench top scale flow-through glass and stainless steel chamber study to evaluate the relationship between measured leaf-air distribution coefficients, as well as leaf kinetics in an attempt to establish a relationship that could be used to calculate indoor air concentrations.

The comparison of estimated indoor air VOC concentrations to measured concentrations suggests that a standard box model can be used to evaluate the risk level of a certain product to contaminate indoor air, given its emission rate. Measured VOC concentrations from a craft glue (E-6000), gun cleaner and a molded plastic lamp base showed that objects can cause indoor air concentrations above the United States Environmental Protection Agencies (USEPA) screening levels for carcinogenic risk-based compounds. These concentrations are thus capable of providing false positives in VI investigations. Correlations between leaf and air concentrations in the different scales of plant studies suggest that leaves can be used to monitor indoor air concentrations for VOCs. Plant species appears to play a role in the plants effectiveness as a sampler. This difference appears to result from physical/chemical differences between species most notably lipid content and density.

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