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NOTE: This page is archived for historical purposes and is no longer being maintained or updated.

	worker climbing into manhole

"Confined Space" refers to a space which, by design, has limited openings for entry and exit, unfavorable natural ventilation which could contain or produce dangerous air contaminants, and which is not intended for continuous worker occupancy.

According to data collected by the U.S. Department of Labor (USDOL), Bureau of Labor Statistics (BLS) Census of Fatal Occupational Injuries (CFOI) program, fatal injuries in confined spaces fluctuated from a low of 81 in 1998 to a high of 100 in 2000 during the five-year period, averaging 92 fatalities per year.

What are types of confined spaces?

Confined spaces include but are not limited to:

  • Storage tanks
  • Compartments of ships
  • Process vessels
  • Pits
  • Silos
  • Vats
  • Degreasers
  • Reaction vessels
  • Boilers
  • Ventilation and exhaust ducts
  • Sewers
  • Tunnels
  • Underground utility vaults
  • Pipelines



Worker Deaths in Confined Spaces
NIOSH Publication No. 94-103 (January 1994)
This publication provides a summary of surveillance findings and the full text of 70 investigative case reports from 70 incidents in which 109 workers died. These incidents and investigations occurred between December 1983 and September 1993.

A Guide to Safety in Confined Spaces
NIOSH Publication No. 87-113 (July 1987)
This manual provides information on recognition of confined spaces and their hazards, and specific safe work practices for testing, monitoring, and ventilating the atmosphere; isolation of energy sources (lockout-tagout); respirators; standby/rescue; and addressing general physical hazards such as temperature extremes, engulfment hazards, slick surfaces, and noise. A checklist for confined space entry is appended.

NIOSH Alert: Request for Assistance in Preventing Occupational Fatalities in Confined Spaces
NIOSH Publication No. 86-110 (January 1986)
This publication emphasizes the hazards faced by workers and rescuers who enter confined spaces. It provides summary case reports of eight fatal incidents that were investigated under the Fatality Assessment and Control Evaluation (FACE) program. The report concludes that in each case there was lack of recognition of the hazards; lack of testing, evaluation, and monitoring; and lack of planned rescue procedures. The Alert provides recommendations for addressing these problems.

Criteria for a Recommended Standard: Working in Confined Spaces
NIOSH Publication No. 80-106 (September 1979)
This publication outlines a classification system for confined spaces (Class A-Immediately Dangerous to Life/Health (IDLH); Class B-dangerous, but not IDLH; Class C-potentially hazardous). It provides a checklist of factors to consider for each class, and provides information on establishing a permit-based entry system, testing and monitoring the atmosphere in a confined space, safe work procedures, and safety equipment and clothing. Other specific topics covered include ventilation, lockout-tagout, rescue, and training.

Fatality Assessment and Control Evaluation (FACE) Program Investigations

Since the inception of the FACE program in 1982, 171 fatal incidents involving confined space entry and rescue efforts have been investigated by NIOSH and State investigators. These links provide lists of those cases which in turn link to the full-text reports.

Health Hazard Evaluations (HHEs)

HHEs are field investigations of possible confined space health and safety hazards in the workplace, conducted under the authority of the Occupational Safety and Health Act of 1970, which authorizes the Secretary of Health and Human Services — following a written request from employees, authorized representative of employees, or employers — to determine whether any substance normally found in the place of employment has potentially toxic effects in such concentrations as used or found.

Other Confined Space Resources