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

INTRODUCTION

Wintertime thermal inversions can lead to the accumulation of small particulate matter (PM). Despite an association between respiratory hospital admissions and elevated PM levels, many people continue to exercise outdoors during inversions. This study compared pulmonary function and exercise performance during periods of low and high ambient PM 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 PM (0.6-14.7 microgram·m), and the other during high PM (19.1-42.5 micrograms·m). A 10 cm visual analog scale (VAS) administered postexercise quantified subjective ratings of respiratory discomfort.

RESULTS

The PM differential between trials was ≥18 micrograms·m 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 PM: 13:54±1:34 min:s; high PM: 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) PM 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 PM, equivalent to yellow or orange on the air quality index.