[1] Univ Hosp, Dept Resp Med, Madrid, Spain
[2] Univ Hosp, Clin Epidemiol Unit, Madrid, Spain
[3] Municipal Inst Med Res, Ctr Res Environm Epidemiol, Barcelona, Spain
[4] Univ Utrecht, Inst Risk Assessment Sci, Environm Epidemiol Div, Utrecht, Netherlands
[5] Univ Hosp Juan Canalejo, La Coruna, Spain
[6] Ctr Invest Biomed & Red Enfermedades Resp, Madrid, Spain
[7] Univ Barcelona, Inst Invest Biomed August & Sunyer, Hosp Clin, Dept Resp Med, Barcelona, Spain
[8] Ctr Inves Biomed & Epidemiol & Salud Publ, Madrid, Spain
[9] Pompeu Fabra Univ, Dept Expt& Hlth Sci, Barcelona, Spain
[10] Autonomous Univ Barcelona, Dept Cellular Biol & Mol Genet, Barcelona, Spain