1. Public Health Division of Gipuzkoa; Department of Health of the Regional Government of the Basque Country; Donostia Spain
2. CIBER of Epidemiology and Public Health; Madrid Spain
3. Biodonostia Research Institute; Donostia Spain
4. Public Health Division of Bizkaia; Department of Health of the Regional Government of the Basque Country; Bilbo Spain
5. Laboratory of Public Health; Regional Government of the Basque Country; Bilbo Spain
6. Environmental Management; Regional Government of the Basque Country; Bilbo Spain
7. Department of Preventive Medicine and Public Health; University of the Basque Country UPV/EHU; Leioa Spain
8. Paediatric Emergency Department; Cruces University Hospital; Basque Health Service; Bilbo Spain
9. Emergency Department; Donostia University Hospital; Basque Health Service; Donostia Spain
10. Allergology Department; Basurto University Hospital; Basque Health Service; Bilbo Spain
11. Department of Paediatrics; Donostia University Hospital; Basque Health Service; Donostia Spain
12. Public Health Division of Alava; Department of Health of the Regional Government of the Basque Country; Vitoria-Gasteiz Spain