1. a National Personal Protective Technology Laboratory, National Institute for Occupational Safety and Health (NIOSH), 626 Cochrans Mill Road, Pittsburgh, PA 15236
2. b Division of Respiratory Disease Studies, NIOSH, 1095 Willowdale Road, Morgantown, WV 26505
3. c Department of Industrial and Management Systems Engineering, West Virginia University, Morgantown, WV 26506