Association between long-term exposure to traffic-related air pollution and lung function: the European Study of Cohorts for Air Pollution Effects (ESCAPE)

Abstract

Background. Acute air pollution effects on lung function are well established and evidence is also strong for long-term effects on lung function growth in children. The chronic impact of ambient air pollutants on lung function in adults remains poorly understood. Aims. We investigated the association of residential traffic-related air pollution with level and decline of lung function in the context of five European cohorts of adults (ECRHS, EGEA, NSHD, SALIA, SAPALDIA). Methods. Residential exposure to nitrogen oxides (NO2, NOx) and particulate matter (PM) was obtained from standardized measurement protocols and land use regression models. Traffic load at the road nearest to participants’ home and on major roads within a 100 meter buffer was assessed. Study-specific analyses were performed with random effects linear regression adjusting for gender, age, height, BMI, education, smoking status. The level and annual decline in the spirometric parameters FEV1, FVC, and FEV1/FVC were considered as outcomes. Cohort-specific results were combined using random-effects meta-analysis. Results. Based on lung function data from 7,613 subjects undergoing spirometry twice over a period of 11 years on average, we observed that a 10 µg/m3 increase in NO2 exposure was associated with lower levels of FEV1 (-13.8 mL (95%CI: -25.82, -2.14)) and FVC (-14.93 mL (-28.73,-1.13)). A higher traffic load at the home address also went along with lower levels of FEV1 and FEV1/FVC. The observed associations were particularly observed in women and generally stronger in participants reporting use of respiratory medication. None of the lung function parameters was related to PM exposure. Conclusions. In this analysis of adults mostly living in urban environments, we observed a lung function decline with increased nitrogen oxide or traffic load exposure. The reported gender differences stimulate research into the underlying mechanisms.