Long-term exposure to low-level air pollution and incidence of asthma: the ELAPSE project

Abstract

Background Long-term exposure to ambient air pollution has been linked to childhood-onset asthma, while evidence is still insufficient. Within the multicentre project “Effects of Low-Level Air Pollution: A Study in Europe” (ELAPSE), we examined the associations of long-term exposures to particulate matter with diameter<2.5 µm (PM2.5), nitrogen dioxide (NO2), and black carbon (BC) with asthma incidence in adults. Methods We pooled data from three cohorts in Denmark and Sweden with information on asthma hospital diagnoses. The average concentrations of air pollutants in 2010 were modelled by hybrid land use regression models at participants’ baseline residential addresses. Associations of air pollution exposures with asthma incidence were explored with Cox proportional hazard models, adjusting for potential confounders. Results Of 98 326 participants, 1965 developed asthma during a 16.6 years mean follow-up. We observed associations in fully adjusted models with hazard ratios and 95% confidence intervals of 1.22 (1.04−1.43) per 5 μg·m−3 for PM2.5, 1.17 (1.10−1.25) per 10 µg·m−3 for NO2, and 1.15 (1.08−1.23) per 0.5 10−5 m−1 for BC. Hazard ratios were larger in cohort subsets with exposure levels below the EU and US limit values and possibly WHO guidelines for PM2.5 and NO2. NO2 and BC estimates remained unchanged in two-pollutant models with PM2.5, whereas PM2.5 estimates were attenuated to unity. The concentration response curves showed no evidence of a threshold. Conclusions Long-term exposure to air pollution, especially from fossil fuel combustion sources such as motorised traffic, was associated with adult-onset asthma, even at levels below the current limit values. Footnotes This manuscript has recently been accepted for publication in the European Respiratory Journal . It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article. Conflict of interest: Dr. Liu has nothing to disclose. Conflict of interest: Dr. Jørgensen has nothing to disclose. Conflict of interest: Dr. Ljungman has nothing to disclose. Conflict of interest: Dr. Pershagen has nothing to disclose. Conflict of interest: Dr. Bellander has nothing to disclose. Conflict of interest: Dr. Leander has nothing to disclose. Conflict of interest: Dr. Magnusson has nothing to disclose. Conflict of interest: Dr. Rizzuto has nothing to disclose. Conflict of interest: Dr. Hvidtfeldt has nothing to disclose. Conflict of interest: Dr. Raaschou-Nielsen has nothing to disclose. Conflict of interest: Dr. Wolf has nothing to disclose. Conflict of interest: Dr. Hoffmann has nothing to disclose. Conflict of interest: Dr. BRUNEKREEF has nothing to disclose. Conflict of interest: Dr. Strak has nothing to disclose. Conflict of interest: Ms. Chen has nothing to disclose. Conflict of interest: Dr. Mehta has nothing to disclose. Conflict of interest: Professor Atkinson has nothing to disclose. Conflict of interest: Mariska Bauwelinck (MSc) has nothing to disclose. Conflict of interest: Dr. Varraso has nothing to disclose. Conflict of interest: Dr. Boutron-Ruault has nothing to disclose. Conflict of interest: Dr. Brandt has nothing to disclose. Conflict of interest: Dr. Cesaroni has nothing to disclose. Conflict of interest: Dr. Forastiere has nothing to disclose. Conflict of interest: Dr. Fecht has nothing to disclose. Conflict of interest: Dr. Gulliver has nothing to disclose. Conflict of interest: Dr. Hertel has nothing to disclose. Conflict of interest: Dr. de Hoogh has nothing to disclose. Conflict of interest: Dr. Janssen has nothing to disclose. Conflict of interest: Dr. Katsouyanni has nothing to disclose. Conflict of interest: Dr. Ketzel has nothing to disclose. Conflict of interest: Dr. Klompmaker has nothing to disclose. Conflict of interest: Dr. Nagel has nothing to disclose. Conflict of interest: Dr. Oftedal has nothing to disclose. Conflict of interest: Dr. Peters has nothing to disclose. Conflict of interest: Dr. Tjønneland has nothing to disclose. Conflict of interest: Dr. Rodopoulou has nothing to disclose. Conflict of interest: Dr. Samoli has nothing to disclose. Conflict of interest: Doris Tove Kristoffersen has nothing to disclose. Conflict of interest: Dr. Sigsgaard has nothing to disclose. Conflict of interest: Dr. Stafoggia has nothing to disclose. Conflict of interest: Dr. Vienneau has nothing to disclose. Conflict of interest: Dr. Weinmayr has nothing to disclose. Conflict of interest: Dr. Hoek has nothing to disclose. Conflict of interest: Dr. Andersen has nothing to disclose.