[1] Univ Utrecht, Environm & Occupat Hlth Unit, Utrecht, Netherlands
[2] GSF, Inst Epidemiol, Neuherberg, Germany
[3] Natl Publ Hlth Inst, Unit Environm Epidemiol, Kuopio, Finland
[4] Municipal Hlth Serv Amsterdam, Dept Environm Med, Amsterdam, Netherlands
[5] GSF, Inst Inhalat Biol, Neuherberg, Germany