Associations between air pollution and pediatric eczema, rhinoconjunctivitis and asthma: A meta-analysis of European birth cohorts

•Uncertainty exists as to the role of air pollution on childhood respiratory health.•Data from five recent European birth cohorts were meta-analyzed.•No evidence found for role of air pollution on asthma and allergies up to 8 years.•Findings consistently null across all cohorts considered. Uncertainly continues to exist regarding the role of air pollution on pediatric asthma and allergic conditions, especially as air pollution levels have started to decrease in recent decades. We examined associations of long-term air pollution levels at the home address with pediatric eczema, rhinoconjunctivitis and asthma prevalences in five birth cohorts (BIB, EDEN, GASPII, RHEA and INMA) from seven areas in five European countries. Current eczema, rhinoconjunctivitis and asthma were assessed in children aged four (N = 6527) and eight years (N = 2489). A multi-morbidity outcome (≥2 conditions versus none) was also defined. Individual outdoor levels of nitrogen dioxide (NO2), nitrogen oxides, mass of particulate matter with an aerodynamic diameter