Title: Interactions between aerobic exercise and ozone exposure: Characterizing the dose-response relationship & examining changes in breathing mechanics
Thesis Supervisor: Dr. Michael Koehle
Committee Members: Dr. William Sheel, Dr. Valerie Bougault
Chair: Dr. Jean-Sébastien Blouin
Abstract:
Introduction: Ozone is an air pollutant present in the low atmosphere that is known to have deleterious effects on respiratory function and contributes to adverse respiratory symptoms. Aerobic exercise increases the amount of air pollution to which an individual is exposed via an increase in ventilation. Despite this, it is not known whether exercise itself alters responses when the inhaled dose of ozone is controlled. Additionally, changes in the mechanics of breathing throughout an ozone exposure have yet to be investigated.
Purpose: In Study I, a bespoke ozone delivery system will be developed and validated to allow for precise regulation of inspired ozone concentration in subsequent experimental studies. Study II will focus on acutely examining the dose-response relationship on an individual level, with responses associated with resting exposure compared to those obtained during moderate intensity exercise and eucapnic hyperpnea. Finally, Study III will delve more specifically into responses during ozone exposure, attempting to understand if and how exposure influences the mechanics of ventilation during exercise.
Methods: In Study I, the developed ozone exposure system will be employed for use in several human exposure studies, with system performance being evaluated across a range of exposure conditions and ventilations. Study II will utilize serial lung function assessment during multiple double-blinded ozone exposures conducted both at rest and during moderate intensity exercise in order to examine response kinetics. Additionally, a novel exposure protocol will also be evaluated to determine whether a eucapnic hyperpnea protocol can adequately model the dose-response characteristics of an exercise exposure. Finally, Study III will delve more specifically into responses during exposure, attempting to understand if and how ozone exposure influences the mechanics of ventilation during exercise. We will employ the use of esophageal balloon catheterization during double-blinded ozone exposures to evaluate whether ozone exposure alters the work of breathing during moderate and severe intensity exercise. In both Studies II & III, comprehensive assessment of participant respiratory health and function will allow for exploratory analyses, aimed at correlating responses to ozone exposure with individual characteristics.
Significance: In combination, these studies will provide novel insight into the interaction between aerobic exercise and ambient ozone exposure. Provided elevated ambient ozone continues to be of concern, understanding its acute impacts on the respiratory system will inform recommendations surrounding physical activity in polluted environments. Furthermore, understanding of the specific kinetics and underlying characteristics of the exercise response will help to inform potential countermeasures.