Title: Investigating Changes in Responses to Controlled Effective Doses of Ozone at Different Exercise Intensities
Supervisor: Dr. Michael Koehle
Committee members: Dr. Valerie Bougault, Dr. Don McKenzie
Abstract: Due to the growing incidence of wildfires, temperature increases with climate change and increased urbanization, more people are exposed to high levels of ground-level zone (O3), a threat exacerbated during exercise by increased ventilation and changes to breathing mechanics. Effective dose is a means to quantify the amount of O3 one is exposed to during a given exercise bout. The effective dose of O3 is the product of the concentration of O3, the ventilation, and the duration of exposure. Typically, as the effective dose of O3 increases, decrements in pulmonary function increase. This study will examine whether changes in exercise intensity result in greater decrements in pulmonary function and subjective symptoms when the effective dose of O3 is controlled. It is hypothesized that exercise performed at a higher intensity while receiving the same effective dose of O3 will result in worsened responses due to changes in breathing mechanics and greater penetration of O3 into the lungs. To test this, a double-blind crossover design will be employed where participants will cycle while exposed to 180 ppb O3 and room air (<10 ppb O3) at a moderate intensity and heavy intensity as characterized by a Step-Ramp-Step VO2max protocol. Throughout each exercise bout and subsequent recovery period, breathing mechanics, pulmonary function, subjective symptoms, and ratings of dyspnea will be measured. Beyond exercise intensity, analysis of results will look to determine whether factors including sex, total lung capacity, and time impact responses to O3.