1. Bureau of Labor Statistics, Industry Injury and Illness Data, Table SNR08, Incidence rates of nonfatal occupational illnesses, by industry and category of illness, 2002. http://www.bls.gov/iif/oshwc/osh/os/ostb1239.pdf. (accessed June 16, 2005).
2. Respirator Usage in Private Sector Firms, 2001; Bureau of Labor Statistics and National Institute for Occupational Safety and Health: Washington, DC, 2003.
3. Approval of Respiratory Protection Devices. Code of Federal Regulations, Part 84, Title 42, 2002.
4. Standard Industrial Classification Manual; Office of Management and Budget, U.S. Government Printing Office: Washington, DC, 1987.
5. Respiratory Protection. Code of Federal Regulations, Part 1910.134, Title 29, 2002.