Date of Award

Spring 1-1-2017

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Lupita D. Montoya

Second Advisor

Angela R. Bielefeldt

Third Advisor

Clint Carroll

Abstract

Most homes on the Navajo Nation (NN) use wood, coal, or a combination of the two fuels for heating in residential stoves that are often old, damaged, or improperly designed for coal use. Health effects from this practice have been observed for residents in the NN cities of Shiprock, NM, Fort Defiance, AZ, and Tuba City, AZ. In response to a call for assessing heating options available in the NN, a mixed-methods framework was developed to identify the most viable options in terms of culture, perception, costs and benefits. A residential wood stove change-out program was supported by findings of all three independent assessments. Next, the combustion emissions of two wood and two coal types commonly used on the NN were characterized with an in-use residential wood stove. On a fuel energy basis, coal compared to wood emitted significantly more fine particulate matter (PM2.5), organic carbon (OC), and carbon monoxide (CO).

The emission factors developed from the testing were then utilized in a chemical mass balance model to predict steady-state indoor concentrations in a “Typical” Navajo home. The model was validated against data from a 2014 indoor air quality study on the NN conducted by the Hannigan research team at CU Boulder. The model-predicted concentrations of PM2.5, EC, and CO were not significantly different than field-measured concentrations for coal burning homes. With further validation, this model may serve to estimate emission reductions from the wood stove change-out program on the NN scheduled for 2017.

Lastly, aqueous extracts of PM2.5 sampled from the emissions tests were assessed using an oxidative stress model in murine macrophage cells. Both wood and coal induced the oxidative stress protein heme oxygenase-1 (HO-1) and the inflammatory cytokine tumor necrosis factor alpha (TNF-α). The magnitude of both responses correlated with mass particle content of low volatile OC, EC, and soluble copper. This research incorporated development of a mixed-methods framework, traditional emissions modeling, residential stove emissions testing, and the use of biological assays to assess the current issue of wood and coal use on the NN.

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