Rationale: Outdoor air quality is associated with respiratory morbidity and mortality. Less is known of the relationship of indoor air quality to respiratory health of groups vulnerable to outdoor air, such as those with chronic obstructive pulmonary disease (COPD).
Objectives: To investigate among patients with COPD the association of health status with indoor air quality in their homes.
Methods: Observational study of indoor environmental characteristics of homes of 148 patients with severe COPD in North East Scotland.
Measurements and main results: Airborne living room levels of particulate matter with a diameter of 2.5 microm or less (PM(2.5)) (microg/m(3)) were measured over 8 to 14 hours using DustTrak monitors. Nitrogen dioxide exposure (ppb) in living rooms was measured over 1 week. Endotoxin (EU [endotoxin units]/mg) in living room dust was measured. Health status of participants was assessed by the St. George's Respiratory Health Questionnaire (symptoms, activity limitation, and disease impact). The mean age of participants was 69 years. Approximately 45% were male, 39% were smokers, and 49% lived in smoking households. Average indoor PM(2.5) levels were 18 mug/m(3), nitrogen dioxide was 7.8 ppb, and endotoxin levels were 95.8 EU/mg of dust. PM(2.5) was significantly higher in smoking households (P < 0.001) and was associated with higher levels of endotoxin and NO(2). PM(2.5) was significantly associated with increased symptom burden (P < 0.01), with greater effect for current smokers. Endotoxin and nitrogen dioxide exposure were not related to health status.
Conclusions: Higher levels of PM(2.5) are associated with worse health status of these patients with severe COPD. Indoor levels of PM(2.5) are significantly higher in homes with smokers.