The association between air pollution and the incidence of idiopathic pulmonary fibrosis in Northern Italy

Acute exacerbations and worsening of idiopathic pulmonary fibrosis (IPF) have been associated with exposure to ozone (O3), nitrogen dioxide (NO2) and particulate matter, but chronic exposure to air pollution might also affect the incidence of IPF. We investigated the association between chronic exposure to NO2, O3 and particulate matter with an aerodynamic diameter <10 μm (PM10) and IPF incidence in Northern Italy between 2005 and 2010. Daily predictions of PM10 concentrations were obtained from spatiotemporal models, and NO2 and O3 hourly concentrations from fixed monitoring stations. We identified areas with homogenous exposure to each pollutant. We built negative binomial models to assess the association between area-specific IPF incidence rate, estimated through administrative databases, and average overall and seasonal PM10, NO2, and 8-hour maximum O3 concentrations. Using unadjusted models, an increment of 10 μg·m-3 in NO2 concentration was associated with an increase between 7.93% (95% CI 0.36-16.08%) and 8.41% (95% CI -0.23-17.80%) in IPF incidence rate, depending on the season. After adjustment for potential confounders, estimated effects were similar in magnitude, but with larger confidence intervals. Although confirmatory studies are needed, our results trace a potential association between exposure to traffic pollution and the development of IPF.