Arterial blood pressure responses to short-term exposure to low and high traffic-related air pollution with and without moderate physical activity

Background: Short-term exposure to traffic-related air pollution (TRAP) has been associated with adverse cardiovascular outcomes. Physical activity (PA) in polluted air may increase pollutant uptake and increase these effects. Methods: Crossover real-world exposure study in 28 healthy participants comparing systolic (SBP) and diastolic blood pressure (DBP) responses to four different exposure scenarios: 2 h exposure in high or low-TRAP environment, each at rest and combined with intermittent moderate PA consisting of 15 min intervals alternating rest and cycling on a stationary bicycle. Data was analyzed using mixed effect models for repeated measures. Results: Exposure to high TRAP was associated with higher DBP (1.1 mm/Hg, p0.002) post-exposure, irrespective of exercise status. Ultrafine particles (UFP) increased DBP post-exposure (0.9 mm/Hg, p0.004). Interquartile increases in black carbon (BC), fine particulate matter (PM₁₀ and PM_coarse), UFP, and nitric oxides (NO_x) were associated with statistically significantly higher SBP post-exposure (1.2, 1.0, 1.1, and 1.1 mm/Hg, respectively). Intermittent PA compared with rest was associated with lower SBP post-exposure (-2.4 mm/Hg, p<0.001). PA lowered SBP more after exposure to the low-TRAP site (-2.3 mm/Hg) compared with the high-TRAP site (-1.6 mm/Hg). We only found evidence of an interaction between PA and both PM₁₀ and PM_coarse, increasing SBP. Conclusion: Both SBP and DBP increase after exposure to TRAP. Intermittent PA attenuates the TRAP-related increases in SBP, with the exception of PM₁₀ and PM_coarse, which potentiate these increases. We showed that in low-TRAP environments intermittent PA has stronger beneficial effects on SBP than in high-TRAP environments.