Long-term exposure to air pollution and greenness and hospitalization for respiratory conditions in Northern Europe: The Life-GAP project

<bold>Background:</bold> Air pollution is linked to increased respiratory morbidity while greenness may benefit respiratory health. Evidence on long-term effects of air pollution and greenness on respiratory hospitalizations is scarce. <bold>Aim:</bold> We evaluated the associations between long-term exposure to particulate matter (PM2.5 and PM10), black carbon (BC), nitrogen dioxide (NO2), ozone (O3) and greenness (normalized difference vegetation index (NDVI), and respiratory hospitalization in the European Community Respiratory Health Survey (ECRHS III). <bold>Methods:</bold> We analyzed data from the ECRHS III, covering respiratory hospitalizations from 2000-2010. A mixed-effect logistic regression was used to assess the relationship between residential air pollution, greenness, and respiratory hospitalizations, adjusting for age, sex, education, body mass index, and smoking. Exposure at residential addresses for 1990 and 2000 was evaluated using the Danish Eulerian Hemispheric Model and the Urban Background Model. <bold>Results:</bold> Of the 1,332 participants, 107 (8.0 %) reported respiratory hospitalization. For 1990, each interquartile range increase in PM2.5, PM10, BC, and NO2 increased hospitalization risk with adjusted odds ratios (ORs) of 1.45 (95% CI: 1.07-1.96), 1.39 (95% CI: 1.07-1.78), 1.36 (95% CI: 0.98-1.88) and 1.30 (95% CI: 0.94-1.80), respectively. Similar tendencies were observed in 2000 exposure, but with lower precision. No associations were seen for O3 and NDVI. <bold>Conclusion:</bold> Long-term exposure to PM, BC and NO2 were associated with increased risk of hospitalization for respiratory conditions, suggesting the health risks of prolonged air pollution exposure.