Safety alert: Confined space hazards
Death and injury continue to occur among construction workers who are required to enter confined spaces. According to the Occupational Safety and Health Administration (OSHA), many workers die and hundreds are injured every year as a result of confined space hazards and accidents on construction sites.
NIOSH (The National Institute for Occupational Safety and Health) defines a confined space as any space that is large enough and so configured that an employee can enter and perform assigned work, has limited or restricted means of entry or exit, and is not designed for continuous employee occupancy.
Examples of confined spaces hazards:
- Excavations and trenches. With excavations and trenches, cave-ins are the greatest risk to workers. Other potential hazards in confined space excavations are falls, falling loads, hazardous atmospheres, and incidents involving mobile equipment. Trench excavations of specific depths must be equipped with a steel trench box that keeps the sides of the excavation from collapsing on workers.
- Vaults, manholes and catch basins. These enclosed concrete structures are typically below ground with limited access, no ventilation and often potentially dangerous utilities such as high voltage electricity, gas or steam lines. Manholes are common on construction sites as entry into and exit from vaults, tanks, pits, etc. Manholes can be particularly dangerous as covers are often removed and not replaced.
- Ventilation ducts. Ventilation ducts are common on construction sites. These sheet metal enclosures move heated and cooled air and exhaust fumes and workers often need to enter through access holes. Inside the duct, there is the potential for oxygen deficiency, and since ductwork usually has many bends, entry and exit and communication with others can be difficult. Electric shock hazards and heat stress can also be a problem.
- Tanks. Used for a variety of purposes on a construction site, including storage of water and chemicals, tanks require entry for cleaning and repairs. Dangers are oxygen deficiency, toxic and explosive atmospheres created by what is stored in the tanks, excess heat, and because electric cords are often taken into the tank, electric shock.
- Sumps. Common on jobsites, sumps collect water and other liquids. Workers that work in sumps will encounter an oxygen-deficient atmosphere, electrical shock hazards due to the power tools used inside and accidents resulting from poor lighting.
- Pipe assemblies. Piping 16 to 36 inches in diameter is used for a variety of purposes. While it might not immediately be recognized as a confined space, it presents several hazards, including oxygen-deficiency, welding fumes from work done inside and outside the pipe, restricted movement, poor communications, electric shock due to ungrounded tools and excess heat.
Confined space hazards
Confined spaces share many of the same potential hazards to workers. Asphyxiation generally results from oxygen deficiency or exposure to toxic atmospheres. While working in vaults, tanks or other confined spaces workers can be exposed to the build-up of dangerous gases created by the contents of the space or the work being performed.
Another hazard associated with confined spaces is material or equipment that falls on workers as they enter, leave or work in a confined space. Vibration can cause materials on top of the space to roll off and cause injury to the workers inside.
Electrocution can result from improperly grounded tools or equipment, as well as failure to properly de-energize equipment. Fatalities have resulted when workers were accidentally drawn into moving parts within a confined space.
Confined spaces are typically poorly lit making any sort of work within more hazardous.
The dangers to rescuers
In the event of a construction accident, other workers will usually attempt a rescue. This can be especially hazardous with accidents that occur in confined spaces. Unorganized and ill-informed rescue attempts have resulted in more fatalities and injuries than the original accident.
OSHA has strict policies to help protect workers from confined space hazards. Confined spaces categorized as “permit required confined spaces” require pre-work permits, thorough air monitoring, rescue equipment, and safety checklists and procedures be in place before work begins. Additional air quality and/or explosive or toxic fumes monitoring is required at periodic intervals.
In addition, employers are required by law to ensure workers are not exposed to unnecessary risk, and both workers and supervisors must complete safety training before working in any confined space.
New OSHA rule on confined space hazards
A new OSHA rule to protect employees from the hazards resulting from exposure to confined spaces in the construction industry is expected to be finalized in March.
The new regulation requires employers to first determine whether there is a confined space at a jobsite. If there is a confined space, the employer must determine if there are existing or potential hazards in the space.
If there are hazards, the employer must classify the space as Isolated-Hazard Confined Space, Controlled-Atmosphere Confined Space, Permit-Required Confined Space or Continuous System-Permit-Required Confined Space. The requirements for each type of confined space are included in the new rule.
OSHA says, if implemented properly, the new rule will reduce the average number of fatalities and injuries in confined spaces covered by the standard by about 90 percent. For more information, visit