Exercise in Thermal Inversions: PM2.5 Air Pollution Effects on Pulmonary Function and Aerobic Performance

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Wilderness & Environmental Medicine






Elsevier Inc.

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Introduction Wintertime thermal inversions can lead to the accumulation of small particulate matter (PM2.5). Despite an association between respiratory hospital admissions and elevated PM2.5 levels, many people continue to exercise outdoors during inversions. This study compared pulmonary function and exercise performance during periods of low and high ambient PM2.5 concentrations. Methods Forced vital capacity and forced expiratory volume in 1 s were measured outdoors before and after two 3200 m running time trials: one with low ambient PM2.5 (0.6–14.7 microgram·m-3), and the other during high PM2.5 (19.1–42.5 micrograms·m-3). A 10 cm visual analog scale (VAS) administered postexercise quantified subjective ratings of respiratory discomfort. Results The PM2.5 differential between trials was ≥18 micrograms·m-3 for 10 healthy runners. Despite feeling more respiratory discomfort (P=0.044) during the bad air trial (VAS: 4.6±1.8 cm) compared with the good air trial (VAS: 2.9±1.8 cm), the 3200 m run time (low PM2.5: 13:54±1:34 min:s; high PM2.5: 14:07±1:44 min:s) was not different (P=0.261) between trials. Postexercise forced vital capacity was not significantly different (P=0.846) between the low (4.86±1.00 L) and high (4.84±0.95 L) PM2.5 conditions. Similarly, the difference in postexercise forced expiratory volume in 1 s was not significant (P=0.750) between trials (4.22±0.89 L vs 4.23±0.85 L). Conclusions Neither run time nor pulmonary function of healthy adults were adversely affected by an acute bout of exercise in elevated ambient PM2.5, equivalent to yellow or orange on the air quality index.

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