1. Department of Occupational and Environmental Health, College of Public Health; University of Iowa; Iowa City Iowa
2. Division of Pediatric Pulmonary Medicine, Allergy, and Immunology; Children's Hospital of Pittsburgh of UPMC, University of Pittsburgh; Pittsburgh Pennsylvania
3. Faculty of Health; Centre for Research and Action in Public Health, University of Canberra; Canberra Australia
4. Department of Epidemiology, College of Public Health; University of Iowa; Iowa City Iowa
5. Department of Environmental & Occupational Health, Faculty of Public Health; Kuwait University; Jabriya Kuwait