Background: Few studies have investigated traffic-related air pollution as a risk factor for respiratory infections during early childhood. Objectives: We aimed to investigate the association between air pollution and pneumonia, croup, and otitis media in 10 European birth cohorts—BAMSE (Sweden), GASPII (Italy), GINIplus and LISAplus (Germany), MAAS (United Kingdom), PIAMA (the Netherlands), and four INMA cohorts (Spain)—and to derive combined effect estimates using meta-analysis. Methods: Parent report of physician-diagnosed pneumonia, otitis media, and croup during early childhood were assessed in relation to annual average pollutant levels [nitrogen dioxide (NO2), nitrogen oxide (NOx), particulate matter ≤ 2.5 μm (PM2.5), PM2.5 absorbance, PM10, PM2.5–10 (coarse PM)], which were estimated using land use regression models and assigned to children based on their residential address at birth. Identical protocols were used to develop regression models for each study area as part of the ESCAPE project. Logistic regression was used to calculate adjusted effect estimates for each study, and random-effects meta-analysis was used to calculate combined estimates. Results: For pneumonia, combined adjusted odds ratios (ORs) were elevated and statistically significant for all pollutants except PM2.5 (e.g., OR = 1.30; 95% CI: 1.02, 1.65 per 10-μg/m3 increase in NO2 and OR = 1.76; 95% CI: 1.00, 3.09 per 10-μg/m3 PM10). For otitis media and croup, results were generally null across all analyses except for NO2 and otitis media (OR = 1.09; 95% CI: 1.02, 1.16 per 10-μg/m3). Conclusion: Our meta-analysis of 10 European birth cohorts within the ESCAPE project found consistent evidence for an association between air pollution and pneumonia in early childhood, and some evidence for an association with otitis media.

The research leading to these results was funded by the European Community’s Seventh Framework Program (FP7/2007–2011) under grant 211250. The BAMSE study was supported by the Swedish Research Council FORMAS (for Environment, Agricultural Sciences and Spatial Planning), the Stockholm County Council, the Swedish Foundation for Health Care Sciences and Allergy Research, and the Swedish Environmental Protection Agency. The GINIplus study was supported for the first 3 years by the Federal Ministry for Education, Science, Research and Technology, Germany (interventional arm) and Helmholtz Zentrum München, Germany (former GSF; National Research Center for Environment and Health) (observational arm). The LISAplus study was supported by grants from the Federal Ministry for Education, Science, Research and Technology, Germany; Helmholtz Zentrum München, Germany (former GSF); Helmholtz Centre for Environmental Research–UFZ, Germany; Marien-Hospital Wesel, Germany; and Pediatric Practice, Bad Honnef, Germany. The PIAMA study is supported by The Netherlands Organization for Health Research and Development; The Netherlands Organization for Scientific Research; The Netherlands Asthma Fund; The Netherlands Ministry of Spatial Planning, Housing, and the Environment; and The Netherlands Ministry of Health, Welfare, and Sport. MAAS was supported by an Asthma UK Grant (04/014); the JP Moulton Charitable Foundation, UK; and the James Trust and Medical Research Council, UK (G0601361). INMA was funded by grants from the Spanish Ministry of Health-Instituto de Salud Carlos III (Red INMA G03/176, CB06/02/0041, FISPI041436, FIS-PI081151, FIS-PI042018, FIS-PI09/02311, FIS-PI06/0867, FIS-PS09/00090, FIS-FEDER 03/1615, 04/1509, 04/1112, 04/1931, 05/1079, 05/1052, 06/1213, 07/0314, and 09/02647); Generalitat de Catalunya-CIRIT, Spain (1999SGR 00241); Conselleria de Sanitat Generalitat Valenciana, Spain; Universidad de Oviedo, Obra social Cajastur, Spain; Department of Health of the Basque Government, Spain (2005111093 and 2009111069); Provincial Government of Gipuzkoa (DFG06/004 and DFG08/001), Spain; and Fundación Roger Torné, Spain. GASPII was funded by The Italian Ministry of Health (ex art.12 D.Lgs 502/92, 2001)