1. Institute of Occupational Medicine and Industrial Hygiene, College of Public Health, National Taiwan University, Taipei, Taiwan, R.O.C
2. Institute of Labor, Occupational Safety and Health, Ministry of Labor, Executive Yuan, Taipei, Taiwan, R.O.C
3. School of Respiratory Therapy, College of Medicine, Taipei Medical University, Taipei, Taiwan, R.O.C
4. Division of Pulmonary Medicine, Department of Internal Medicine, Shuang Ho Hospital, Taipei Medical University, Taipei, Taiwan, R.O.C
5. Industrial Technology Research Institute, Hsinchu, Taiwan, R.O.C
6. Department of Public Health, College of Public Health, National Taiwan University, Taipei, Taiwan, R.O.C