Confined spaces are found in nearly every industry and pose a challenge for workplace safety.
Confined spaces present serious risks to the workers who must enter them. Of course, it's possible (and necessary) to mitigate those risks. With a thorough understanding of confined spaces, the hazards of working in them, and how they can be managed, workers can complete their tasks safely and efficiently.
So what exactly is a confined space and what sort of PPE do you need to work safely in one? Keeping reading to find out.
What Makes a Space a Confined Space?
There are a few criteria that a work area must meet to be considered a confined space:
- The space is not necessarily designed for workers, but is large enough for someone to enter and perform certain tasks
- The space has limited or restricted means of entry and exit
- The space is not designed for continuous occupancy
Examples of commonly encountered confined spaces include:
- Tanks
- Vessels
- Silos
- Storage bins
- Vaults
- Manholes
- Tunnels
- Ductwork
- Pipelines
OSHA deems some confined spaces “permit-required.” As the name implies, only workers who are trained and hold the required permit may enter these especially hazardous confined spaces. Permit-required spaces:
- May contain a hazardous or potentially hazardous atmosphere
- May contain material that can engulf an entrant
- May contain walls that converge inward or floors that slope downward, which could trap an entrant
- May contain other physical hazards, such as unguarded machines or exposed live wires
- Must be identified by the employer, who must then inform exposed employees of the location of such spaces and their hazards
Common Confined Space Hazards
Confined space hazards are numerous and they can prove dangerous or fatal to workers who don’t take the necessary precautions. Fully understanding these hazards is a critical part of making informed decisions about what sort of PPE will be required.
Oxygen Deficiency
The leading cause of death among workers in confined spaces is oxygen deficiency. Brain damage can occur and the heart may stop after only a short amount of time in an oxygen deficient environment. The only way to detect low oxygen levels (those below 19.5 percent) is to test the air.
Low oxygen levels may result from:
- Rusting metals and combustion
- Oxygen being replaced by other gases (for example, welding gases)
- Micro-organisms (such as those present in sewer lines)
Oxygen Enrichment
While it’s not as common as low oxygen, too much oxygen (more than 21 percent) is also dangerous to the occupants of a confined space. It increases the risk of fire or explosion and can be detected only by using a properly calibrated oxygen monitor.
Toxic Atmosphere
Even with normal oxygen levels, there may be contaminants in the air that are hazardous to a worker's health.
Common toxic gases in confined spaces include hydrogen sulfide, which has a distinct rotten egg smell, and carbon monoxide, which is both odorless and colorless.
Flammable or Explosive Atmosphere
The right mixture of air and gas can easily lead to an explosion. The critical factors include:
- Oxygen content
- Presence of flammable gas or vapor
- Presence of dust
- Ignition sources (including tool sparks, welding operations, and smoking)
Engulfment Hazards
Either liquids or solids can quickly engulf a space and trap or asphyxiate the workers inside it. Common hazards include water or sewage flow and loose, granular materials like grain, sand, and coal.
Physical Hazards
Potential physical hazards in confined spaces include:
- Noise
- Extreme heat or cold
- Radiation
- Vibration
- Electrical hazard
- Inadequate lighting within the space
Limited Communication
Communication is key to keeping confined space workers safe – particularly when there is no direct line of sight between those outside the space and those in it.
Without reliable communication, workers inside have no way to call for help or alert supervisors to potentially unsafe conditions. It also means that supervisors have no real way to confirm the safety of those inside, which puts lives at risk.
Managing Hazards with the Right PPE
Despite the severe hazards that confined spaces pose, there’s good news. Proper confined space PPE can protect workers during their shifts – and even save lives. While engineering and administrative control measures should be applied first, personal protective equipment offers a final (and critical) line of defense for workers.
Here’s what you need to know.
Fall Protection
All workers – not just those entering the space – must be outfitted with fall protection. Employees working near openings (like manholes) should wear a restraint lanyard or fall arrest lifeline.
Workers entering the confined space must don a chest or full-body harness with a retrieval line sufficient to allow for the successful removal of the worker in case of emergency. The harness can be attached to a self-retracting lifeline, which acts as a personal fall arrest system should a fall take place. Workers not familiar with fall protection equipment must be properly trained before they may use it. Special attention should be paid to ensure that the fall protection doesn’t interfere with free movement in the space.
Note, however, that using dorsal mounted D-ring to perform a rescue comes with an additional risk: putting an unconscious worker's neck and head in danger. Any full-body harness used in confined spaces, then, should have accessory rings at the shoulders to facilitate a safer rescue.
An estimated 60 percent of confined space fatalities happen during botched rescue operations. It’s critical, then, that rescuers be trained and wear fall protection, as well. It doesn’t take much for one incident to turn into a complex, multi-person rescue.
Gas Detection
In confined space work, gas detection equipment is treated as PPE. Employers must provide the equipment to workers at no cost, maintain the devices, and give training on how to use them.
Before entering the space, the atmosphere must be tested for oxygen content, flammable gases and vapors, and toxic air contaminants – in that order. Atmospheric testing helps evaluate the hazards and confirm that the space is safe for entry. For this reason, a reliable multi-gas detector is a must-have for confined space work.
Respiratory Protection
Respiratory protection is required under OSHA rules anytime a space does not meet the following conditions:
- Oxygen: 19.5 to 23.5 percent
- Flammability: below 10 percent of lower flammable limit for gases, vapors, mists, or combustible dust
- Toxic gases: below the permissible exposure limit or time-weighted average of a substance
If there is a need for a breathing apparatus, entrants must use a self-contained breathing apparatus (SCBA) or supplied air respirator. Be sure to consider the type of work being done when making your selection; the length of the air line hose will limit user movement.
Rescuers should also be equipped with respirators that are well maintained and ready to use in the event of a rescue.
Communication Devices
Communication gear is a critical part of keeping workers safe inside a confined space, and as such, it should fall under the PPE umbrella. There are a number of things you need to look for in communication devices:
- Hands-free
- Wireless
- Full-duplex
- Independently powered
- Integrated with hearing protection
Cell phones should be avoided. They require workers to dial on a keypad to reach someone and mobile service can be spotty and unreliable. Two-way radios are also wireless, and are therefore susceptible to service interruptions as well.
Wearable devices are an excellent option to help protect workers while on the job. Wearable tech that is appropriate for confined space work ranges from headsets and helmets to smart watches and phones. The devices are usually hands-free, and therefore ideal for use in confined spaces that can be difficult to maneuver in. Options include devices to measure brain activity, alert supervisors when a worker falls or experiences fatigue, detect gas, and pinpoint the exact location of the wearer. Rapidly changing technology means that this area of PPE is definitely one to watch.
Other Protective Gear
When it comes to hazards like loud noise and falling objects, workers must be ready. Anyone entering a confined space should wear a full safety suit made of material that can protect against toxic or irritating substances. Workers entering a space that has extreme temperature hazards must wear protection suitable for the circumstances.
If there is the risk of head injury or falling objects, workers must wear a safety helmet that complies with international standards. All workers must wear eye and face protection, including safety goggles where there is a risk of eye-irritating chemicals, vapors, or dusts. Workers must also use gloves made of a material suitable to the hazards present in the space. Note that specialty gloves may be necessary to protect workers from extreme heat or cold or when using specific tools.
Shoes and boots should comply with safety codes and offer good traction on slippery surfaces. Additional considerations may be made for workers in spaces that have slip hazards, electricity, falling objects, chemicals, or sparks.
Finally, workers who are exposed to excessive noise must wear hearing protection. It’s important to consider communication, however, as workers inside a confined space must be able to communicate with those outside it with ease.
Conclusion
Confined space work is inherently risky, but being equipped with the right PPE for the task at hand is essential for remaining safe. Whether it’s a sewer or silo, pipeline or tunnel, understanding the hazards is the first step to selecting the PPE that can best help you manage them.
For all things Confined Space, check out our Confined Space Knowledge Center.