1. Associate Professor, Dept. of Occupational Safety and Health, China Medical Univ., Taichung, Taiwan, ROC. E-mail: kpchao@mail.cmu.edu.tw
2. Associate Professor, Dept. of Civil Engineering, Ching-Yun Univ., Chungli, Taiwan, ROC.
3. Graduate Student, Institute of Environmental Health, China Medical Univ., Taichung, Taiwan, ROC.