Association of air pollution exposure with exercise-induced oxygen desaturation in COPD

Background There is a link between exposure to air pollution and the increased prevalence of chronic obstructive pulmonary disease (COPD) and declining pulmonary function, but the association with O-2 desaturation during exercise in COPD patients with emphysema is unclear. Our aims were to estimate the prevalence of O-2 desaturation during exercise in patients with COPD, and determine the association of exposure to air pollution with exercise-induced desaturation (EID), the degree of emphysema, and dynamic hyperinflation (DH). Methods We assessed the effects of 10-year prior to the HRCT assessment and 7 days prior to the six-minute walking test exposure to particulate matter with an aerodynamic diameter of < 10 mu m (PM10) or of < 2.5 mu M (PM2.5), nitrogen dioxide (NO2), and ozone (O-3) in patients with emphysema in this retrospective cohort study. EID was defined as a nadir standard pulse oximetry (SpO(2)) level of < 90% or a delta (o)SpO(2) level of >= 4%. Ambient air pollutant (PM2.5, PM10, O-3, and NO2) data were obtained from Taiwan Environmental Protection Administration (EPA) air-monitoring stations, usually within 10 km to each participant's home address. Results We recruited 141 subjects with emphysema. 41.1% of patients with emphysema exhibited EID, and patients with EID had more dyspnea, worse lung function, more severe emphysema, more frequent acute exacerbations, managed a shorter walking distance, had DH, and greater long-term exposure to air pollution than those without EID. We observed that levels of 10-year concentrations of PM10, PM2.5, and NO2 were significantly associated with EID, PM10 and PM2.5 were associated with the severity of emphysema, and associated with DH in patients with emphysema. In contrast, short-term exposure did not have any effect on patients. Conclusion Long-term exposure to ambient PM10, PM2.5 and NO2, but not O-3, was associated with EID.

Automated summary

This study aimed to evaluate the prevalence of exercise-induced desaturation (EID) in COPD patients with emphysema and determine its association with air pollution exposure, emphysema severity, and dynamic hyperinflation (DH). The results showed that long-term exposure to PM10, PM2.5, and NO2 was associated with EID.