Close quarters

The hazards of confined spaces

May 1, 2014

Key points

  • Confined spaces have limited exits and entrances, and can force employees to work in positions that are hard on the body.
  • Confined space hazards include ergonomics, heat and struck-by.
  • Experts recommend always having a second worker outside the confined space to communicate with the worker.

The roll of duct tape was only 5 feet away, resting inside a reactor chamber at a refinery. The chamber was being purged with nitrogen, and cleanliness criteria dictated that the roll of tape could not be there. In an attempt to retrieve it, one worker either fell or intentionally went inside and – due to the near-zero oxygen concentration within the reactor – was dead within minutes, according to a Chemical Safety Board report on the incident.

The situation, already horrific, then got worse.

An onsite foreman quickly descended the reactor’s ladder in an apparent rescue attempt. He never returned.

“All too often, and as this case illustrates, would-be rescuers become victims,” the CSB report states.

CSB went on to say that the double-fatality case, which occurred in Delaware in 2006, offers important lessons: Confined spaces can be dangerous even if they do not appear to be, and proper safety and rescue precautions must be taken when working in them.

According to OSHA, about 90 deaths involving confined spaces occur every year. Guy Colonna, division manager for industrial and chemical engineering at the National Fire Protection Association in Quincy, MA, said such incidents may occur because workers and employers do not know what confined spaces actually are or what dangers may lurk inside. One study concluded 40 percent of confined space fatalities involve attempted rescuers.

“They’re still failing to recognize a space as having the attributes of a confined space, and they’re making assumptions about the space and going in without the proper safeguards,” Colonna said.

Defining confined spaces

Generally, a confined space is large enough for a person to enter, has limited or restricted means of exit, and is not designed for continuous human occupancy, according to Gary Flores, EHS regional director for Strike USA, a pipeline manufacturer and service provider based in The Woodlands, TX. Everything from tanks and tunnels to manholes and silos can be considered confined spaces.

Colonna stressed that confined spaces do not always have to be an area with only one opening. An area may have several openings but would still be considered a confined space if those openings are 15 feet off the ground. Likewise, a space with multiple openings can be considered a confined space if a worker has to crawl under and over various obstructions to get to the opening.

A “permit-required” confined space contains one or more of the following characteristics:

  • A hazardous atmosphere or the potential for one
  • Material, such as grain, that could potentially engulf an individual
  • Walls converging inward or floors sloping downward and tapering into a smaller area that could trap or asphyxiate an individual
  • Any other recognized safety or health hazards, including unguarded machinery and heat stress

Employers are required to alert workers of the location and the dangers of permit-required confined spaces. This can be done with signs or by other methods, the Washington-based American Federation of State, County and Municipal Employees states.


The buddy system

To help protect a worker inside a confined space, many stakeholders consider it a best practice to have a second worker on the outside. OSHA advises these workers to always maintain contact through either visual, phone or radio means. This monitoring allows the attendant to order the worker in the confined space to evacuate, and to contact emergency personnel to help with rescue if necessary.

Although not all types of work require an outside individual, David LeGrande, health and safety director for the Washington-based Communication Workers of America, stressed that it is a best practice for that worker to monitor the situation, and said some states have enacted provisions requiring the second worker regardless of the type of work.

A confined space may have been tested to be clear for entrance, but an airborne contaminant may be at ground level in the confined space and not noticeable until the employee begins to work at the lower level. That individual could then be overcome by the substance and pass out.

“And that’s why it’s so important to have a second person above ground,” LeGrande said.

This outside worker should be trained in first aid and CPR, he said, and should be able to perform emergency procedures that could include helping the worker get out of the confined space.


LeGrande worries that employers are failing to adequately train employees about working in confined spaces. Instead of going through proper procedures, warning employees of all possible hazards and explaining precautions to take, he said, employers are focusing on completing the work.

“It’s all spurred by this drive to increase performance and productivity,” he said.

Denise Bowles, health and safety specialist with the American Federation of State, County and Municipal Employees, said AFSCME wants workers who are trained to think about their confined workplaces and ask whether they can get in and out safely.

Bowles has learned of situations in which new workers learn from colleagues who have been on the job for years, but who have not had formal training on confined space hazards and are entering the areas incorrectly.

Workers should be trained on the dangers they could face in a confined space, procedures for safe entry and exit, and what protective gear they should have, AFSCME states. Employers also should train workers on the company’s written confined space program, Flores suggested, including air monitoring, safe work practices, lockout/tagout and an emergency action plan.

Confined space incidents

Read a list of NIOSH Fatality Assessment and Control Evaluation Reports.

Proper equipment

Bowles suggested going through confined space equipment to make sure it is still in good shape. If damaged, it may not operate effectively, putting workers at risk.

“Take a look at the equipment you have and make an honest assessment of the useful life of it,” said Dianne Matthew Brown, AFSCME health and safety specialist. “A lot of stuff gets thrown around and it takes abuse it was never meant to take.”

Bowles knows of a municipality that, to help ensure its gear stays in good condition, places all confined space equipment in a single trailer. When employees must perform confined space work, they hook the trailer up to their truck and tow it to the site, use the equipment, and return it to its proper location before towing it back to the main facility.

“It makes it easy, and you don’t have to worry about the equipment being thrown in the back of the truck,” Bowles said.

Emergency response

Workers in confined spaces should be hooked up to equipment that can retrieve them if they are overcome. Unfortunately, this is not always possible.

“They have to crawl over and under pipes that are in that space,” Bowles said. In those situations, workers may have to unhook from retrieval equipment. If something goes wrong, that individual will not be quickly pulled out – the attendant on the outside no longer has visual contact, and cannot safely go into the confined space without proper protection against whatever incapacitated the victim.

Some worksites have emergency response teams on standby, and Brown suggested establishing a relationship with local emergency services. All personnel should be trained on emergency procedures, a written plan and the emergency retrieval systems, according to Flores. Employees should know all potential hazards, and none should attempt a rescue without being trained, he added.

Rescue scenarios could be avoided if proper safety procedures are followed beforehand – even with pressures to get the job done quickly, Bowles said.

“Your job is to get services back online, but we want to make sure we do it safely,” she said.


Confined spaces have many unique hazards in addition to the “regular” hazards – ergonomics or struck-bys, for example – that workers may come across in a non-confined space setting.

“Our folks have seen all kinds of stuff,” said Denise Bowles, health and safety specialist with the American Federation of State, County and Municipal Employees, whose members frequently work in manholes and underground vaults. “There’s a lot of junk that ends up in there,” Bowles said, including bugs, snakes and decomposing animals.

Even typical work-related hazards can be exacerbated by the conditions inside a confined space.

“Fitting in the manhole and getting the work done can often be an issue,” said David LeGrande, health and safety director for the Communication Workers of America, headquartered in Washington.


The leading cause of death in confined spaces is asphyxiation, generally the result of oxygen deficiency or exposure to toxic atmospheres, according to OSHA. Additionally, the lack of ventilation in a confined space increases a worker’s potential for exposure to any airborne hazard, LeGrande said.

Before entering a confined space, workers should test the atmosphere for sufficient oxygen content. Blower equipment may be needed to ensure proper ventilation, LeGrande said, and AFSCME advises continuous ventilation to ensure the hazardous atmosphere does not re-form while workers are inside. However, LeGrande cautioned that blowers may not be effective in all confined spaces, such as older manholes that are deep and narrow.

Although OSHA standards specify that employers retest air levels as often as necessary, several experts who spoke to Safety+Health said workers should have continuous monitoring to ensure levels stay within a safe zone.

“With the advancement of instruments, most people ought to be able to get closer to continuous monitoring,” said Guy Colonna, division manager for industrial and chemical engineering at the National Fire Protection Association in Quincy, MA.

LeGrande warned that while low oxygen content is an expected hazard in confined spaces, hazardous chemicals such as gasoline can leach into confined spaces as well – unbeknownst to workers until they are inside the area. As an example, he pointed to manholes – hundreds of thousands exist across the country, and records on their conditions are poor. LeGrande believes manholes of particular concern are those “in concentrated geographical areas – areas with lot of people, thus a greater amount of industry and contaminants.”

But busy metropolitan areas are not the only places hazardous chemicals or substances can enter confined spaces. LeGrande said areas near gas stations may be at risk for chemicals leaching into nearby confined spaces.


Temperatures in a confined space can reach dangerous levels, especially in hotter climates and confined spaces that are metal tanks, according to Colonna.

“If you’re working in an empty steel box, which is essentially what these tanks are, they get very hot very quickly,” he said, noting that temperatures can be upward of 140° F in some situations.

To protect workers from heat stress or heat stroke, Colonna recommended instituting work-rest procedures that limit employees to 15 minutes of work in a hot enclosed space. In scenarios with extreme temperatures, work-rest procedures alone may not be the safest option – employers may need to design and install air-conditioning units to lower the temperature.


Being able to see is often an important part of getting work done. Unfortunately, “a confined space normally doesn’t come with installed overhead lighting for your convenience,” Colonna said.

As a result, additional hazards – such as slips, trips or falls – can arise. Employers should equip employees working in confined spaces with hard hats to protect their heads from inadvertent strikes.

Also, Colonna warned that not every light source is certified for a confined space environment. In an environment with a flammable atmosphere, any unapproved electrical lighting source could have unprotected circuitry. Gases and vapors can then get inside the circuitry and, when the light is turned on, ignite. Make sure any electrical lighting has been approved for use in a confined space, Colonna said.

Cramped quarters

The layout of a confined space may force workers to be careful about how they position themselves, LeGrande said.

Employees might end up in a position that makes it difficult to move while working, Colonna said, adding that even getting to the location where the work is to be conducted can be difficult and hard on the body. “You find yourself contorting your body to get to every place you might need,” he said. Employers should monitor how long workers are in such positions, and evaluate the length of time it is safe to remain there, Colonna added.


Proper lockout/tagout and hazardous energy control standards should be followed when workers are in confined spaces. Workers inside a machine such as a mixer or stirrer are vulnerable to inadvertent startups that could injure or kill them.

Colonna shared the example of an incident in which a grain inspector was aboard a ship inspecting cargo holds, and someone failed to lock out and de-energize the auger. The auger was activated, and the inspector and a terminal worker were killed.