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Development and Application of Exhaled Breath Biomarkers for Studying Health Effects of Air Pollution

Jicheng Gong
Master of Science, Peking University – 2006

Thesis Advisor: Junfeng (Jim) Zhang, Ph.D.
Graduate Program in Environmental Sciences/Exposure Science

School of Public Health
Room 334 (3rd floor)

Wednesday, September 28, 2011
12:00 noon


Numerous experimental and epidemiological studies have been conducted to examine the health effects of air pollution exposure in humans. There are still aspects that remain to be better understood, for example, the toxicity of ultrafine particles, and the mechanisms by which air pollutants affect the respiratory and other systems. The overall goal of this dissertation research is to develop and apply exhaled breath biomarkers to understand how air pollutants affect the respiratory health in a group of school children and a group of young adults, all free of chronic diseases. The dissertation consists of the following two major components.
1. I analyzed the data collected on a group of school children to examine the biological relevance of several metrics (number, surface area, active surface area, and volume concentrations) for ambient particles in various size modes in relation to fractional exhaled nitric oxide (FeNO), a biomarker of pulmonary inflammation. The main findings from this analysis include the following. (i) In terms of number concentration, particles in the Aitken mode (23-70 nm) and the accumulation mode (71-800 nm) were each significantly and positively associated with FeNO, whereas particles in the nucleation mode (3-22 nm) were significantly and negatively associated with FeNO. (ii) UFPs, measured as a lamp-sum of both nucleation-mode and Aitken–mode particles, did not show a significant association with FeNO. (iii) Particles contributing largely to the surface area concentration and/or the volume concentration of ambient particles and particles deposited in the respiratory tract had a significant and positive association with FeNO.
2. We measured MDA in exhaled breath condensate (EBC) and urine samples to examine (i) whether a substantial reduction in air pollution during the 2008 Beijing Olympics resulted in a reduction in MDA, and (ii) whether MDA concentrations were associated with concentrations of air pollutants. From the pre-Olympic to the during-Olympic period, concentrations of air pollutants were reduced by up to 60%, accompanied by a significant decrease (26%) in EBC MDA but not in urinary MDA. Sulfur dioxide, carbon monoxide, PM2.5, and PM2.5 components (sulfate, EC, and OC), each was significantly associated with EBC MDA. Urinary MDA was associated with none of the pollutants measured. Significant decreases in EBC MDA associated with the Olympic air pollution control period and significant associations of EBC MDA with pollutants suggest that air pollution exposure increase lipid peroxidation (oxidative stress burden) in the respiratory tract. In contrast, no effects of air pollution were observed on lipid peroxidation in the systemic circulation.

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