Physical exercise attenuates the negative effects of short-term exposure to medium air pollution levels on cardio-respiratory responses

Abstract Background Air pollution (AP) has become a substantial environmental issue affecting human cardiorespiratory health. Physical exercise (PE) is widely accepted to promote cardiorespiratory health. There is a paucity of research on the point at which the level of polluted environment engaged in PE could be used as a preventive approach to compensate for the damages of AP. Objectives To determine the effects of PE on cardio-respiratory and inflammatory responses in different levels of short-term exposure to AP among healthy young adults. Methods We constructed a real-world crossover study of 30 healthy young adults with repeated measures. Participants participated in 90 min of moderate-intensity PE in different (low, medium, high) AP exposure scenarios. Cardiorespiratory measurements and blood samples were collected before and after the intervention. The percentage changes in cardiorespiratory health markers after exercise in the three AP levels environments were compared using linear mixed-effects models. Results Compared to the changes observed post-exercise in the low-level AP environment, only PEF (-9.36, P = 0.018) showed a significant decrease, and eosinophils showed a significant increase in the medium-level environment (25.64, P = 0.022), with no significant differences in other indicators. Conversely, post-exercise in the high-level AP environment resulted in a significant increase in DBP (6.5, P = 0.05), lung inflammation (FeNO: 13.3, p < 0.001), inflammatory cell counts (WBC: 27.0, p < 0.001; neutrophils: 26.8, p < 0.001; lymphocytes: 32.2, p < 0.001; monocytes: 28.2, p < 0.001; and eosinophils: 48.9, p < 0.001), and inflammatory factors (IL-1β: 0.76, P = 0.003; IL-10: 0.17, P = 0.02; IL-6: 0.1, P = 0.17; TNF-α: 0.97, P = 0.011; CRP: 0.17, P = 0.003). Additionally, there were significant declines in lung function parameters, including FVC (-6.84, P = 0.04), FEV1 (-8.97, P = 0.009), and PEF (-9.50, P = 0.013). Conclusions PE in medium and low-level AP environments seems relatively safe for cardiorespiratory health among healthy young adults. However, PE in high-level AP environments can be detrimental to cardiorespiratory health, significantly increasing the body's inflammatory response.