[1] Univ Utrecht, Inst Risk Assessment Sci, Environm & Occupat Hlth Div, NL-3508 TD Utrecht, Netherlands
[2] Natl Res Ctr Hlth & Environm, Inst Epidemiol, Neuherberg, Germany
[3] Natl Publ Hlth Inst, Environm Epidemiol Unit, Kuopio, Finland
[4] Municipal Hlth Serv Amsterdam, Dept Environm Med, Amsterdam, Netherlands
[5] Natl Res Ctr Hlth & Environm, Inst Inhalat Biol, Neuherberg, Germany
[6] Univ Helsinki, Dept Phys, Helsinki, Finland