A listing of safe personal protective devices and reliable industrial hazard measuring instruments certified by NIOSH as of December 31, 1991 was provided. Useful information concerning certified coal mine dust personal sampler units and respirators was provided in tabular form. Updated lists of approval applicants, and lists of some of the more common cautions and limitations for specific respirator classes were provided. Also included were names and addresses of manufacturers and distributors of certified equipment, self contained breathing apparatus for enter and escape, for escape only, and combined self contained breathing apparatus and supplied air respirators. Gas masks were listed which are useful for specific exposures. Types of supplied air respirators described include Type-C continuous flow, pressure demand, and demand, Type-CE abrasive blasting, Type-A, and Type-B. Particulate respirators were discussed for single use, for dusts and mists, for fumes and mist, and for high efficiency. Chemical cartridge types were listed for protection from specific toxic gases. Powered air purifiers were also included.