Outdoor air pollution and respiratory health in patients with COPD

Objectives Time series studies have shown adverse effects of outdoor air pollution on mortality and hospital admissions in patients with chronic obstructive pulmonary disease (COPD) but panel studies have been inconsistent. This study investigates short-term effects of outdoor nitrogen dioxide, ozone, sulfur dioxide, particulate matter (PM10) and black smoke on exacerbations, respiratory symptoms and lung function in 94 patients with COPD in east London. Methods Patients were recruited from an outpatient clinic and were asked to complete daily diary cards (median follow-up 518 days) recording exacerbations, symptoms and lung function, and the amount of time spent outdoors. Outdoor air pollution exposure (lag 1 day) was obtained from local background monitoring stations. Results Symptoms but not lung function showed associations with raised pollution levels. Dyspnoea was significantly associated with PM10 (increase in odds for an IQR change in pollutant: 13% (95% CI 4% to 23%)) and this association remained after adjustment for other the pollutants measured. An IQR increase in nitrogen dioxide was associated with a 6% (0-13%) increase in the odds of a symptomatic fall in peak flow rate. The corresponding effect sizes for PM10 and black smoke were 12% (2-25%) and 7% (1-13%), respectively. Conclusion It is concluded that outdoor air pollution is associated with important adverse effects on symptoms in patients with COPD living in London.