Using smog chambers to estimate the toxic effects of reactive atmospheric mixtures Public Deposited

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Last Modified
  • March 21, 2019
Creator
  • Doyle, Melanie Lynn
    • Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
Abstract
  • We live in a dynamic environment with atmospheric pollutants constantly transforming, interacting with one another, and generating secondary pollutants. Many of these secondary pollutants have not been identified and, because they are often more oxygenated, many are more toxic than their parent compounds. Continuous emissions from biogenic and anthropogenic sources into this reactive environment create problematic conditions for evaluating the respiratory toxicity of exposure to individual components of urban atmospheres. While previous investigations have studied individual atmospheric components of air pollution, the evaluation of "one atmosphere" effects has been limited by experimental complexities. In this work, new techniques were developed to create an air-liquid interface exposure system coupled with a controllable atmospheric reactor, or "smog chamber", and these were used to examine various reactive atmospheric mixtures using a laboratory setting that still mimicked the outdoor environment. This smog chamber - in vitro exposure system combines common techniques used in classic toxicology with an outdoor environmental chamber system that was developed to investigate chemical reaction mechanisms. This dissertation is divided into three main parts that demonstrate new methods to study reactive atmospheric pollutants utilizing the smog chamber - in vitro exposure system. In the first part, 1,3-butadiene and isoprene were used to evaluate the differences in respiratory toxicity between unreacted parent pollutants and their complete mixture of products generated during photochemical transformations. The second part applied similar techniques to differentiate the roles that specific photochemical products play in the induction of toxicity mediators; in particular, the role of ozone effects compared to the other known, first generation products. In addition to determining the effects induced by product mixtures generated during photochemical transformations, understanding which products induce the greatest overall effect is particularly helpful when regulating ambient pollutants. In the final part, a preconditioning method was developed to ascertain if repeated ozone exposures modify the respiratory effects induced by subsequent challenges to atmospheric mixtures. Combined, these results characterize and estimate the toxic potential of a realistic, complex, reacting, polluted atmosphere.
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  • In Copyright
Advisor
  • Jeffries, H. E.
Degree granting institution
  • University of North Carolina at Chapel Hill
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  • Open access
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