Preventing Occupational Fatalities in Confined Spaces

Confined spaces may be encountered in virtually any occupation; therefore, their recognition is the first step in preventing fatalities. Since deaths in confined spaces often occur because the atmosphere is oxygen-deficient or toxic, confined spaces should be tested before entry and continually monitored as personnel work in these environments.

According to data collected by the U.S. Department of Labor (USDOL), Bureau of Labor Statistics (BLS) Census of Fatal Occupational Injuries (CFOI) program, there are 92 fatalities in confined spaces per year, averaging almost two per week. And more than 60% of confined space fatalities occur among would-be rescuers. According to OSHA, over 4.8 million confined space entries are made every year in the United States. Over 11,000 injuries could be prevented if employers and workers had simply implemented a well-designed and properly executed monitoring and rescue plan and followed the procedures outlined under 29 CFR 1910. 146.

What Is A Confined Space?

The Occupational Safety and Health Administration (OSHA) defines a confined space in 29 CFR 1926.21 as “any space having a limited means of egress, which is subject to the accumulation of toxic or flammable contaminants or has an oxygen-deficient atmosphere.” Many workplaces contain areas that are considered “confined spaces” because while they are not necessarily designed for people, they are large enough for workers to enter and perform certain jobs. Examples of 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, and pipelines.

OSHA also uses the term “permit-required confined space” (permit space) to describe a confined space that has one or more of the following characteristics:

  • contains or has the potential to contain a hazardous atmosphere;
  • contains material that has the potential to engulf an entrant;
  • has walls that converge inward or floors that slope downward and taper into a smaller area which could trap or asphyxiate an entrant; or
  • contains any other recognized safety or health hazard, such as unguarded machinery, exposed live wires, or heat stress.

Because of these characteristics, this type of confined space can be considered an Immediately Dangerous to Life or Health (IDLH) environment because of exposure to airborne contaminants that are “likely to cause death or immediate or delayed permanent adverse health effects or prevent escape from such an environment.” IDLH values developed by National Institute for Occupational Safety and Health (NIOSH) are often used to guide the selection of breathing apparatus made available to workers or firefighters in specific situations. This is why the selection of proper respiratory equipment is paramount before entering an IDLH environment (respiratory equipment suggestions are linked below in this post).

“Non-permit required spaces” do not contain or, with respect to atmospheric hazards, have the potential to contain any hazard capable of causing death or serious physical harm. These are places that may be tough to get into but aren’t going to hold dangers to your breathing or the sort of engulfment hazards you might find in a grain elevator or similar facilities.

It is imperative that if you work in confined space areas, you take proper precautions before and during your work, as it could mean the difference between life and death!

Case Study of Fatal Incidents

Based on information derived from several case studies across a two-year span by NIOSH, they concluded that the majority of the fatalities occurred as a result of encountering one or more of the following potential hazards:

  • Lack of natural ventilation
  • Oxygen deficient atmosphere
  • Flammable/explosive atmosphere
  • Unexpected release of hazardous energy
  • Limited entry and exit
  • Dangerous concentrations of air contaminants
  • Physical barriers or limitations to movement
  • Instability of stored product

In each of these cases, there was a lack of recognition and testingevaluation, and monitoring before entry, nor had a well-planned rescue been attempted. These incident reports suggest that recognizing a confined space in conjunction with the proper testing, evaluation, and monitoring of the atmosphere and development of appropriate rescue procedures could prevent such deaths.


In light of their case findings regarding occupational deaths in confined spaces, NIOSH recommends that managers, supervisors, and workers be made familiar with the following three steps:

1. Recognition

Worker training is essential to recognize what constitutes a confined space and the hazards that may be encountered in them. This training should stress that death to the worker is likely if proper precautions are not taken before entry is made.

2. Testing, Evaluation, and Monitoring

A qualified person should test all confined spaces before entry to determine whether the confined space atmosphere is safe for entry. Tests should be made for oxygen level, flammability, and known or suspected toxic substances. Evaluation of the confined space should consider the following:

  • Methods for isolating the space by mechanical or electrical means (i.e., double block and bleed, lockout, etc.)
  • Institution of lockout-tagout procedures
  • Ventilation of the space using a blower that’s powerful enough to fully ventilate that particular confined space. Using our Confined Space Blower Selector Tool will help calculate the CFM needed from your blower to completely ventilate your space for safe working conditions. Some types of ventilation blowers are:
  • Cleaning and/or purging
  • Work procedures, including use of safety lines attached to the person working in the confined space and its use by a standby person if trouble develops
  • Personal Protective Equipment required, such as clothing, boots, and respirators listed below:
  • Special tools required
  • Communications system to be used

The confined space should be continuously monitored to determine whether the confined space’s atmosphere has changed due to the work being performed.

For more information on any of our products, please contact our customer service department or call us at 800.622.3530 

3. Rescue

Rescue procedures should be established before entry and should be specific for each type of confined space. A standby person should be assigned for each entry where warranted. The standby person should be equipped with rescue equipment, including a safety line attached to the worker in the confined space, self-contained breathing apparatus, protective clothing, boots, etc. The standby person should use this attached safety line to help rescue the worker. The rescue procedures should be practiced frequently enough to provide a level of proficiency that eliminates life-threatening rescue attempts and ensures efficient and calm response to any emergency.