Confined Spaces, the Hazards & Worker Protection in Confined Spaces

What Confined Spaces

Confined spaces represent significant health and safety risks for many workers. Recognising and planning appropriately for confined space work can mean distinguishing between a job well done and a disaster.

This article presents essential information to be used as a guideline for safety and protection working in confined spaces, with particular emphasis on appropriate personal protective equipment selection. This publication is not a technical instruction manual nor all-inclusive in content or scope.

Confined spaces exist in many sizes and shapes. They are found in heavy industry, food, chemical, and petroleum processing, utility and communications installations, and construction sites, to name just a few. The following areas are typically classified as confined spaces and should be treated with caution:

• Storage tanks
• Pump wet wells
• Degreasers
• Sewers and septic tanks
• Pipelines
• Pits
• Furnaces
• Manholes
• Tunnels
• Boilers
• Silos
• Vessels
• Grain elevators
• Mixers
• Open-topped water tanks
• Water towers
• Bottom-access enclosures
• Railcar tanks
• Slaughterhouse blood pits
   

In most cases, these confined spaces are relatively easy to spot. When areas with determined space characteristics are not included in the listing above, it is always best to treat unknown areas and their interior environments as confined spaces and take all necessary safety precautions.

Confined Spaces May Be Hazardous

Hazards found in confined spaces appear in one of six groups:

• Atmospheric
• Physical
• Engulfment
• Corrosive
• Biological
• Other hazards
   

Physical hazards within the work area should be identified after atmospheric hazards of a confined space have been identified. Physical hazards, such as grinding equipment, agitators, steam or steam fittings, mulching equipment, drive shafts, gears, and other moving parts, can pose a danger within confined spaces, and burn, maim or crush confined space entrants.

Engulfment hazards frequently exist within areas where loose materials such as grains, crushed stone, or sawdust are stored. Often housed within silos or other containment equipment, these materials harbour air pockets that can collapse under a worker’s weight. Engulfment hazards either block workers’ airways or compress their upper body to suffocate.

Corrosive hazards such as acids, solvents, and cleaning solutions can pose additional confined space hazards. Contact between these substances and skin, mucous membranes, or eyes can cause severe irritation or burns. Vapours released by these materials can also irritate the respiratory system and cause gastrointestinal distress.

Biological hazards such as mould mildew and spores frequently found in the dark, damp spaces can irritate the respiratory system. Bacteria and viruses in applications such as sewage treatment plants can also threaten the body with various diseases. In addition, bird and animal faeces can present severe human health hazards.

Other hazards, such as poor visibility, inadequate lighting, electrical wiring installations that are not up to code, and insecure footing, can cause significant confined space safety hazards. Confined spaces may also harbour rodents, snakes, spiders, or insects, which may be hazardous to confined space entrants. Finally, sudden changes in wind or weather can contribute to unexpected variations within confined space environments.

Worker Protection in Confined Spaces

Tools and equipment required to complete confined space tasks must be collected before confined space entry. Lack of proper equipment can pose dangerous situations for workers and waste valuable work time.

All equipment should be checked before use and in good working order. Protective measures should also be taken to protect people working outside the confined space area; barricades should be erected to protect passers-by from open utility holes, hatch entrances, and other unmarked confined space area entrances.

Proper respiratory protection should be selected once confined space atmospheres have been analysed and should be provided to all confined space entrants. Recommended confined space respirator types include SCBA (self-contained breathing apparatus), dual-purpose SCBA, combination air-line respirators with escape cylinders, air-purifying devices, and escape respirators. Because these devices vary in design, application, and protective capability, it is essential to assess work site contaminant levels first.

MSA Safety Confined Spaces Protection

Self-Contained Breathing Apparatus (SCBA) provide the highest level of respiratory protection, as they protect workers within oxygen-deficient atmospheres. SCBA is equipped with user-worn air cylinders that provide dependable yet limited air supply without hoses or tethers to impede movement.

Air-purifying respirators are designed for use only within atmospheres containing sufficient oxygen to sustain life (at least 19.5%) and containing known concentrations of gases, vapours, and particulates. These devices use special filters/chemical cartridges to remove specific gases, vapours, dust, mists, and fumes from ambient air. For respirators to be effective, levels of contaminants must be within the concentration limitations of the specific respirator and filter.

Head protection should be worn by all workers entering confined spaces to protect the wearer from maximum impact. The employer should determine the necessary safety based on hazards within a specific work area. Workers should not be allowed to enter confined spaces without appropriate head protection.

Eye protection in the form of protective spectacles or goggles helps to shield workers’ eyes from flying debris. For additional face protection, face shields are available for protection against splashes and debris. Made for use with helmet-mounted frames or protective headgear, MSA recommends that face shields be worn over impacted-rated spectacles or goggles.

Hearing protection products provide hearing protection from noises commonly generated within confined spaces. By their nature, confined spaces tend to reverberate and amplify even small sounds, creating potentially serious auditory hazards for workers. Aural protectors frequently take two forms: flexible plugs that insert into workers’ ear canals or earmuffs that cover each ear.

Communication equipment is critical within confined space work areas. Reliable communication equipment allows workers to communicate amongst themselves and with work area attendants stationed outside. In an emergency, communication equipment allows for help to be summoned quickly. Contact must be maintained between workers and attendants stationed outside when working in confined spaces. Battery-operated, voice-activated communication systems are frequently used, allowing workers to move freely within confined spaces, eliminating the need to hand-operate communication devices.

Confined space entry kits and retrieval equipment may be necessary to facilitate entry into and exit from confined spaces. Proper retrieval systems for workers and equipment consist of a full-body harness, a heavy-duty lifeline, a tripod, and a personnel /material hoist. Retrieval equipment helps lower workers into confined spaces as it controls the descent rate and prevents accidental falls into the work area. Additional work hoists are frequently used to raise more inadequate tools and equipment. Every entrant should wear a full-body harness and have some lifeline attached to the harness, even in horizontal entry applications. If an entrant becomes non-responsive, the lifeline can be used to haul the worker out as a non-entry rescue.

Multigas monitors are available to simultaneously monitor oxygen, combustible, and toxic gases. Toxic gases and vapours that can be inhaled or absorbed through the skin are frequently found within confined spaces. Sometimes these atmospheric hazards displace oxygen and may make the body incapable of maintaining respiration. Some toxic gases and vapours can also cause long-term physical damage to the body in cases of repeated exposure.

As a result, careful planning and preparation of all personnel involved in confined space entry should occur before anyone enters work areas.

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