Information on chemical hazards was provided in tabular form in this pocket guide for use as a quick reference source relating to general industrial hygiene and medical surveillance practices. The guide is intended for use by workers, employers and occupational health professionals. Minor technical changes are included in the second printing (February, 1987). Chemical names and synonyms, exposure limits and recommendations, chemical and physical properties, incompatibilities of one substance with another, analytical methods, respiratory and personal protective equipment recommendations, toxicological route that the hazardous material takes in humans (inhalation, skin absorption, ingestion, skin or eye contact), signs and symptoms of exposure, target organs, and procedures for emergency treatment are provided for various substances deemed to be chemical hazards in the workplace. Potentially hazardous substances or conditions evaluated by NIOSH through July of 1986 were tabulated. A section was included on the best use of the pocket guide.