associations between exposure to traffic-related air pollutants and parameters of respiratory health for the dutch and the swedish centres will be published in separate papers. analyses of the respiratory symptom data of the dutch part of the TRAPCA study have shown an association between exposure to traffic-related air pollution and wheeze and asthma in the first 2 yrs of life. the signification between cough and air pollution in the german cohort could not be confirmed. in sweden there was a nonsignificant positive association between asthma at the age of 2 yrs and air pollution. since the diagnosis of specific respiratory illnesses during the first years of life is difficult, a more definitive conclusion about the risk of traffic-related air pollution on respiratory health and in particular on asthma requires further studies when the children are older