Particulate Matter 2.5 Level Modulates Brachial Artery Flow-Mediated Dilation Response to Aerobic Exercise in Healthy Young Men

Particulate matter 2.5 (PM2.5) is an environmental pollutant linked with the risk of cardiovascular disease. Aerobic exercise performed in polluted environments may have fewer benefits because of increased PM2.5 inhalation during exercise. However, the vascular responses to aerobic exercise in high PM2.5 (HPM2.5) conditions remain unknown. This study aimed to examine the acute flow-mediated dilation (FMD) response to moderate-intensity treadmill running in HPM2.5 levels compared to low PM2.5 (LPM2.5) levels in healthy young males. Treadmill running in both HPM2.5 and LPM2.5 levels was completed by nine subjects. Brachial artery FMD was measured before and after the exercise to assess vascular endothelial function. Indoor PM2.5 concentration was significantly higher in HPM2.5 than in LPM2.5 conditions (p < 0.001). Scaled FMD significantly increased after the exercise in LPM2.5 conditions but not in HPM2.5 (p = 0.03), and baseline diameter increased only in HPM2.5 conditions after the exercise (p = 0.001). Baseline diameter and peak diameter were smaller, and time to peak dilation was delayed in HPM2.5 compared to LPM2.5 in pre-exercise intervention measurements (p < 0.05). Therefore, acute PM2.5 exposure can counteract the positive effect of aerobic exercise on vascular endothelial function in young males.