Year of Award

2013

Document Type

Dissertation

Degree Type

Doctor of Philosophy (PhD)

Degree Name

Toxicology

Department or School/College

Department of Biomedical and Pharmaceutical Sciences

Committee Chair

Curtis W. Noonan

Commitee Members

Tony J. Ward, Andrij Holian, Christopher Migliaccio, Christopher Palmer

Keywords

ASTHMATIC CHILDREN, COARSE PARTICULATE MATTER, EVALUATING EXPOSURES, HEALTH EFFECTS, INDOOR

Abstract

The primary aim of the ARTIS study (Asthma Randomized Trial of Indoor Wood Smoke) is to improve the quality of life of asthmatic children living in wood stove homes by reducing in-home fine particulate matter (PM2.5). In the original project, characterizing exposure to the coarse fraction of particulate matter (consisting of particles <10 μm and >2.5 μm; PMc) was not proposed. The coarse fraction has been shown to elicit increased pulmonary inflammation compared to PM2.5. This may be due to biogenic constituents of PMc such as endotoxin, a component of the cell wall of Gram-negative bacteria. Scientific interest in the coarse fraction is on the rise due to its unique documented adverse health effects and potential for regulatory status. A novel filterbased sampler (coarse particle environmental monitor, CPEM) was used to characterize coarse fraction and airborne endotoxin concentrations in a subset of ARTIS homes. In 50 homes, only the presence of pets was associated with PMc concentrations. The frequency of wood stove use (loading/stoking) was not associated with either PMc or airborne endotoxin concentrations. Following 43 homes from pre- to post-intervention, homes that received an active filter intervention had a 27.4 μg/m3 greater reduction in PM2.5 relative to a placebo intervention with a treatment effect of ~90%. The placebo filters were unexpectedly efficient in significantly reducing PMc and airborne endotoxin concentrations. As a result, the active filter intervention showed no enhanced ability to reduce PMc and airborne endotoxin relative to the placebo intervention. These effects remained significant when the filter units were run at least 50% of the time. Finally, baseline health outcomes were investigated for association with PMc and airborne endotoxin concentrations in 38 asthmatic children living in the wood stove homes. As a whole we found a more general pro-inflammatory and oxidative stress response to increased endotoxin concentrations as opposed to the phenotypic allergic asthma response. We also found separate and unique health outcome associations with PMc and airborne endotoxin. Overall, these studies significantly advance our understanding of in-home exposures, health effects, and reduction efforts of asthma exacerbating agents in wood stove homes.

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© Copyright 2013 Marcy Lynn McNamara