Relationship of long-term air pollution exposure with chronic obstructive pulmonary disease: an Italian multicentre observational study.

Background: Recent evidence showed that 50% of chronic obstructive pulmonary disease (COPD) may be attributable to air pollution. We aimed to investigate the association between long-term air pollution exposure and COPD symptoms/diagnosis in an Italian epidemiological study.

Methods: A total of 14 420 adults living in Ancona, Pavia, Pisa, Sassari, Turin and Verona were investigated in 2005-2011. Data on risk factors and health outcomes were collected by questionnaires; mean annual concentrations of particulate matters (PM) like PM₁₀ and PM_2.5 as well as NO₂ and mean summer concentrations of O₃ (µg/m³) at residential level with a 1 km resolution (period 2013-2015) were obtained by machine learning techniques. The relationship of pollutant exposure and COPD prevalence was assessed by logistic regression models (single pollutant) and principal component logistic regression models (multipollutant) adjusting for sex, age, education level, smoking habits, season of interview, and city-specific climatic index and including a random intercept for cohorts.

Results: A 10 µg/m³ increase of PM₁₀, PM_2.5 and NO₂ exposure was related to COPD diagnosis and symptoms (OR 1.31, 95% CI 1.03 to 1.65 for PM_2.5; OR 1.26, 95% CI 1.03 to 1.54 for PM₁₀ and OR 1.07, 95% CI 1.00 to 1.15 for NO₂) using a multipollutant approach. Similar results emerged for dyspnoea (OR 1.24, 95% CI 1.05 to 1.47 for PM_2.5; OR 1.21, 95% CI 1.05 to 1.39 for PM₁₀ and OR 1.06, 95% CI 1.01 to 1.11 for NO₂). Associations between COPD symptoms and summer O₃ were less clear. By multipollutant models, OR estimates were lower than those by single pollutant models.

Conclusions: Further evidence about the relationship between air pollution and respiratory effects in Italian adults was provided indicating PM as the main driver.