Winter air pollution and disease parameters in advanced chronic obstructive pulmonary disease panels residing in Denver, Colorado

Background: Ambient pollution might worsen chronic obstructive pulmonary disease (COPD). Objective: We explored the associations of pollution to pulmonary function, rescue medication, and symptoms over 2 winters in 2 panels of subjects with advanced COPD in Denver, Colorado. Methods: Subjects measured lung function and recorded symptoms and rescue medications. Daily ambient pollution concentrations for particulate matter (PM10 and PM2.5), carbon monoxide (CO), and nitrogen dioxide (NO2) were obtained for Denver. Estimated effects of pollution on outcomes were derived for the same day and I and 2 days after pollution measurements (lags 0, 1, and 2, respectively). Results: Sixteen (mean age, 65.8 years; mean FEV1, 42.3% of predicted value) and 18 (mean age, 67.4 years; mean FEV1, 39.4% of predicted value) subjects participated in the first and second winters, respectively. There were no differences in demographic or disease characteristics between the 2 panels. In the first winter no detrimental associations were found. In the second winter, however, there were significant detrimental associations of CO in the morning and PM10, CO, and NO2 in the evening, increasing medication use at lag 0. Total symptom score increased at lag 0 with NO2. The concentrations of particulates were increased in the second winter compared with in the first winter, and this winter was colder and more humid. Conclusions: In the second winter, subjects with severe COPD had worse lung function at lags 0 and I and increased rescue medication at lag 0 with increases in ambient air pollution. The effects of pollution varied between the 2 winters, perhaps related to levels of pollution and weather patterns. Significant effects were seen despite ambient pollution levels that conformed to US Environmental Protection Agency standards.