Title: “Impact of traffic-related air pollution on the cardiovascular response to exercise in patients with hypertension“
Thesis Supervisor: Dr. Michael Koehle
Committee members: Dr. Christopher Carlsten, Dr. Robert Petrella, Dr. Mark Gelfer
Chair: Dr. Bill Sheel
Abstract: Evidence from epidemiological, modelling, and experimental studies suggest that the health benefits of exercise in healthy populations outweigh the risks of air pollution in all but the most extreme air pollution concentrations. However, there is a paucity of evidence in patients with hypertension, a subgroup considered susceptible to the adverse cardiovascular effects of air population. The objective of this thesis was to assess the impact of traffic-related air pollution on the cardiovascular response to exercise in patients with hypertension. Methods: Adults aged 40-70 years old with hypertension or on anti-hypertensive medications completed a real-world, randomized, crossover study. Participants completed two 30-minute exercise bouts: once along a commercial street (i.e., high traffic) and once in an urban plaza (i.e., low traffic). Blood pressure, heart rate variability, and arterial stiffness was measured prior to and up to 26 hours following exercise. Black carbon (BC), noise, relative humidity, and temperature were measured during each exercise bout. Results: Exercising in the low traffic site was associated with a significantly (p < 0.05) lower post-exercise systolic blood pressure (-5.69 mm Hg [95% CI -9.74 to -1.63]) and mean arterial pressure (-3.45 mm Hg [95% CI -6.43 to -0.47]), relative to the high traffic site. An interquartile increase in BC (1296 ng/m3) was significantly associated with a 3.19 mm Hg (95% CI 0.84 to 5.40) and 2.22 mm Hg (95% CI 0.60 to 3.84) increase in systolic blood pressure and mean arterial pressure up to 2 hours post-exercise, respectively, as well as a 3.91 mm Hg (95% CI 2.31 to 5.61) increase in evening (i.e., 18:30 to 22:00; 2 to 5.5 hours post-exercise) systolic blood pressure. No effect was observed on heart rate variability and arterial stiffness. Conclusion: Exposure to traffic-related air pollution during exercise may attenuate or eliminate the beneficial short-term blood pressure response to exercise in patients with hypertension.