Acute effects of urban air pollution on respiratory health of children with and without chronic respiratory symptoms

Objectives-To investigate to what extent different components of air pollut ion are associated with acute respiratory health effects in children with a nd without chronic respiratory symptoms. Methods-During three consecutive winters starting in 1992-3, peak expirator y flow (PEF) and respiratory symptoms were registered daily in panels of ch ildren of 7-11 years old with and without symptoms, living in urban areas w ith high traffic intensity in The Netherlands. Simultaneously, panels of ch ildren living in non-urban areas were studied. Daily measurements of partic les with aerodynamic diameter <10 pm (PM10), black smoke (BS), sulphate, SO 2, and NO2 were performed in both areas. Results-The contrast in particle concentrations (PM10, BS, and sulphate) be tween urban and non-urban areas was small, but there was more contrast in t he concentrations of SO2 and NO2. In children with symptoms from both areas , significant associations were found between PM10, BS, and sulphate concen trations and the prevalence of symptoms of the lower respiratory tract (LRS ) and decrements in PEF. Particle concentrations were also associated with use of bronchodilators in the urban areas, but not in the non-urban areas. After stratification by use of medication, stronger associations were found in children who used medication than in children who did not use medicatio n. The magnitude of the estimated effects was in the order of a twofold inc rease in the use of bronchodilators, a 50% increase in LRS, and an 80% incr ease in decrements in PEF for a 100 mu g/m(3) increase in the 5 day mean PM 10 concentration. In children without symptoms, significant associations we re found between concentrations of PM10 and BS and decrements in PEF in bot h areas, but these associations were smaller than those for children with s ymptoms. No associations with respiratory symptoms were found. Conclusions-The results suggest that children with symptoms are more suscep tible to the effects of particulate air pollution than children without sym ptoms, and that use of medication for asthma does not prevent the adverse e ffects of particulate air pollution in children with symptoms.