Occupational Safety and Health Administration OSHA

OSHA Hazard Information Bulletins
Calcium Hypochlorite (CaCl2O2)

November 14, 1991




  • Director
  • Office of Field Programs


  • Director
  • Directorate of Technical Support


  • Hazard Information Bulletin - Calcium Hypochlorite (CaCl2O2)

The Directorate of Technical Support issues Hazard Information Bulletins (HIBs) in accordance with OSHA Instructions CPL 2.65 to provide relevant information regarding unrecognized or misunderstood health hazards, inadequacies of materials, devices, techniques, and engineering controls. HIBs are initiated based on information provided by the field staff, studies, reports and concerns expressed by safety and health professionals, employers, and the public. Information is compiled based on a thorough comprehensive evaluation of available facts, literature and in coordination with appropriate parties. HIBs do not necessarily reflect OSHA policy.

The Center for Emergency Response Planning (CERP) brought to OSHA's attention potential hazard(s) associated with calcium hypochlorite. Calcium hypochlorite (hypochlorous acid, calcium salt, losantin, oxychloride and chlorinated lime) is a white, crystal and oxidizing solid material which looks much like table salt.[1] It has a faint odor of chlorine and is toxic by ingestion, skin contact and inhalation. Calcium hypochlorite is used as a disinfectant in swimming pools, sewage treatment operations and in water treatment operations.

Calcium hypochlorite should not be stored near reactive or combustible materials. Fires evolving calcium hypochlorite may be difficult to put out because if calcium hypochlorite is not kept completely dry, it will decompose liberating oxygen and chlorine. A self perpetuating fire/explosion could result if CaCl2O2 is not kept dry and stored with other organic and/or flammable material(s).[2] Therefore, calcium hypochlorite must be stored in a completely dry location, isolated from combustible materials or fully dissolved to prevent creating a hazardous condition.

Please distribute this bulletin to all Area Offices, State Plan States and Consultation Project.

References used:

  1. Center for Emergency Response Planning, "Hazard Alert - Calcium Hypochlorite" AFL-CIO/Workplace Health Fund, Washington, D.C., 1991.
  2. Hawley, G.G, "The Condensed Chemical Dictionary" Van Nostrand Reinhold Company. New York. page 182, 1990.
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