The ability of particles with a 50% cut-off aerodynamic diameter of 10 microm (PM10) to cause respiratory health effects possibly depends on their composition. This study evaluated whether the soluble elemental concentrations in PM10 were related to acute respiratory health effects. The Pollution Effects on Asthmatic Children in Europe (PEACE) study is a multicentre study of the acute effects of PM10 and other air pollution components on the respiratory health of children with chronic respiratory symptoms in urban and suburban panels. Children, 1208, divided among 17 panels were followed for > or =2 months. Exposure to air pollution was monitored on a daily basis. Health status was monitored by twice daily peak expiratory flow (PEF) measurements and a symptom diary. Median concentrations of iron ranged 105-1,110 ng x m(-3) in the urban and 32-517 ng x m(-3) in the suburban locations. The daily concentrations of most elements were not associated with daily variation in PEF, prevalence of respiratory symptoms or bronchodilator use. Silicon and iron concentrations tended to be negatively associated with PEF, and positively associated with the prevalence of phlegm. In two pollutant models, PM10 effect-estimates on phlegm prevalence were reduced and lost significance, whereas the effect-estimates of iron or silicon remained essentially unchanged. The effects of silicon and iron could not be separated. In conclusion, this study provides only weak support for the hypothesis that daily fluctuations in soluble elemental concentrations in ambient particulate matter are responsible for acute health effects.