RATIONALE: Air pollution contributes additively to COPD morbidity beyond tobacco exposure. Limited current data focuses on the impact of fine particulate matter ≤ 2.5 µm in aerodynamic diameter (PM2.5) on COPD pathogenesis and CT-detected lung abnormalities. OBJECTIVE: To test the association between long term PM2.5 and CT measures of lung disease. METHODS: We studied participants enrolled in the SPIROMICS cohort (age 40-80 years; > = 20 pack-years). As part of the SPIROMICS Air study, 10-year mean outdoor concentrations of PM2.5 prior to enrollment at each participant's home were estimated using a hierarchical high-resolution spatiotemporal model. Using baseline chest CT scans completed at study enrollment, functional small airway disease and emphysema were quantified as percentages of total lung volume. We tested the association between PM2.5 and measures of emphysema (PRMEMPH), functional small airway disease (PRMfsad), and large airway disease (Pi10) using mixed effect regression models. Additional mixed effect regression models tested the association of PM2.5 with FEV1 and symptom scores. We stratified all analyses by baseline severity of airflow obstruction on spirometry: none (GOLD 0), mild-moderate (GOLD 1-2) and severe (GOLD 3-4), and non-tobacco exposed, healthy control participants. RESULTS: Among the 2,355 participants aged 40-80 years old included in this analysis, 176 were non-tobacco exposed control participants, 754 were GOLD 0, 982 GOLD 1-2 and 443 GOLD 3-4. Median 10-year average outdoor PM2.5 concentration for the entire cohort was 10.73 μg/m3 with an interquartile range of 3.52 μg/m3. In GOLD 0 participants, prior 10-year PM2.5 exposure was associated with greater baseline emphysema (1.33, 95% CI 1.12,1.59 per one IQR increase) and functional small airway disease (1.22, 95% CI 1.06, 1.40); and lower FEV1 -68.8 ml -126.3, -11.3. Interaction analysis revealed an association between 10-year PM2.5 exposures and greater baseline symptom scores limited to women younger than 65 in the GOLD 0 and control group. No significant associations were found in participants with COPD. CONCLUSION: PM2.5 exposure was associated with CT-detected emphysema and small airway disease as well as lower FEV1 among those with smoking history and no airflow obstruction. Additionally, PM2.5 exposure was associated with greater symptom scores in women younger than 65 years.
Bosma et al. (Tue,) studied this question.