1. Department of Otolaryngology, Tainan Hospital, Department of Health, 125 Zhongshan Road, West Central District, Tainan City 700, Taiwan
2. Department of Environmental and Occupational Health, Medical College, National Cheng Kung University, 138 Sheng-Li Road, North District, Tainan City 704, Taiwan
3. Department of Otolaryngology, Medical College and Hospital, National Cheng Kung University, 138 Sheng-Li Road, North District, Tainan City 704, Taiwan
4. Institute of Occupational Safety and Health, Council of Labor Affairs, Executive Yuan, 99, Lane 407, Heng-Ke Road, Si-Jhih City, Taipei County 221, Taiwan
5. Department of Occupational Safety and Health, College of Public Health, China Medical University, 91 Hsueh-Shih Road, Taichung City 404, Taiwan
6. Department of Environmental and Occupational Medicine, Medical College, National Taiwan University, Room C339, 17 Syu-Jhou Road, Jhong-Jheng District, Taipei City 100, Taiwan
7. Department of Occupational Safety and Health, Chung Hwa University of Medical Technology, 89 Wun-Hua First Street, Ren-De Township, Tainan County 717, Taiwan