Learn about confined space safety, the hazards involved, permit-required confined spaces, and safety tips to stay safe in confined spaces.
Published 15 Dec 2021
Confined space safety is the practice of ensuring safe work conditions in fully or partially enclosed areas such as manholes, pipelines, boilers, utility vaults, and storage bins. Confined space safety precautions should be undertaken accordingly to comply with health and safety regulations and prevent work-related injuries, illnesses, or even deaths.
According to the U.S. Occupational Safety and Health Administration (OSHA), a confined space is an area large enough to fully enter or perform certain jobs. A confined space also has limited or restricted means of entry or exit (e.g. portals, hatches, manholes, ladders, spiral stairways, crawl spaces or long distance to exit) and is not designed for continuous occupancy. Apart from the OSHA criteria, confined spaces are defined across countries or regions as follows:
Based on the definition of the National Institute for Occupational Safety and Health (NIOSH), a confined space refers to a space which, by design, has limited openings for entry and exit, unfavorable natural ventilation which could contain or produce dangerous air contaminants, and which is not intended for continuous worker occupancy.
While OSHA enforces regulations, NIOSH provides research-based recommendations to prevent work-related injuries. Therefore, it is empirical that NIOSH includes the element of “unfavorable natural ventilation” in their definition of a confined space.
As the regulator of occupational health and safety legislation in the U.K, the Health and Safety Executive (HSE) explains that a confined space is a place which is substantially enclosed (though not always entirely), and where serious injury can occur from substances or conditions within the space or nearby (e.g. lack of oxygen).
While OSHA and NIOSH specify that a confined space is not designed or intended for continuous worker occupancy, the HSE emphasizes that a confined space safety does not only include substances or conditions within the area, but also nearby or around it.
The Canadian Centre for Occupational Health and Safety (CCOHS) probably offers the most detailed description of a confined space. CCOHS elaborates that a confined is a fully or partially enclosed space that is not primarily designed or intended for continuous human occupancy and has limited or restricted entrance or exit, or a configuration that can complicate first aid, rescue, evacuation, or other emergency response activities.
However, the CCOHS adds that a confined space is a fully or partially enclosed space that can represent a risk for the health and safety of anyone who enters, due to one or more of the following factors:
As a statutory agency based in the Canadian province of British Columbia, WorkSafeBC simply states that a confined space is an enclosed or partially enclosed area that is big enough for a worker to enter.
Nevertheless, they gave examples of a confined space that is enclosed on all sides such as a tank, or as few as two sides such as an enclosed conveyor. WorkSafeBC concurs that confined spaces are not designed for someone to work in regularly.
According to the definition of Safe Work Australia (SWA), a confined space is determined by the hazards associated with the specific situation—not just because work is performed in a small space.
As the Australian government statutory body for developing national policy relating to work health and safety (WHS) and workers’ compensation, SWA stresses that hazards in a confined space are not always obvious and may change from one entry point to the next.
Examples of confined spaces include tanks, vaults, pits, manholes, tunnels, equipment housings, pipelines, boilers, furnaces, compactors, sewers, attic spaces and elevator pits. Common work performed in confined spaces include maintenance, inspection, repair, and cleaning.
A permit-required confined space also known as a “permit space” contains or has the potential to contain a hazardous atmosphere or any other serious safety or health hazards. Permit-required confined spaces are characterized as a high-risk workplace, requiring regulatory permits and strict entry and safety procedures.
OSHA 1910.146 is the standard for confined spaces. It is found in Title 29 (Labor) Subtitle B (Regulations Relating to Labor) Part 1910 (Occupational Safety and Health Standards) Subpart J (General Environmental Controls). The OSHA confined space standard explains the requirements for permit-required confined spaces in detail. Generally, listed below are some OSHA confined space requirements:
A confined space rescue plan is a system of steps undertaken by designated personnel to rescue employees from permit spaces. The rescue and emergency services often use a retrieval system, or the equipment used for non-entry rescue of persons from permit spaces, among other equipment necessary for safe entry into and rescue from permit spaces. The OSHA requirements related to a confined space rescue plan is as follows:
Statistics show that an average of 90 people died each year while working in confined spaces in the United States alone. Most of these incidents are caused by asphyxiation or oxygen deficiency due to the presence of deadly gases while performing certain jobs.
Detailed safety procedures must be thoroughly conducted to ensure all entrants will be provided adequate protection while performing their job inside the confined space. Moreover, employers are responsible for educating and reinforcing their workers about safety rules.
The main hazard when working in a confined space is the deadly atmosphere due to the presence of carbon monoxide, hydrogen sulfide, and methane gas that may result in oxygen deficiency or asphyxiation. Other common confined space hazards include unguarded machinery, exposed live wires, and heat stress.
Outside the confined space, 21 percent oxygen is necessary to sustain life. Oxygen in confined spaces tends to go low. It might be used for rust, bacterial growth, and slime. Other gas may enter the confined space and displace the oxygen. Operations like heating will consume oxygen.
If oxygen is reduced to 12 to 16 percent, workers will increase pulse and respiration and experience loss of coordination. If the oxygen decreases to 6 to 10 percent, they will experience nausea, vomiting, loss of consciousness, and even death.
Confined spaces, particularly permit spaces, must be areas only accessible by trained professionals. Here are some general safety rules to help you stay safe in confined spaces:
Working in a confined space requires deep knowledge about safety procedures and protocols to secure all entrants from known hazards. iAuditor by SafetyCulture is a mobile app and cloud-based solution that empowers teams to collect consistent data to ensure adequate protection was provided to all entrants while performing their job inside a confined space.
With iAuditor, safety officers can perform confined space risk assessments on mobile devices anytime, anywhere—even while offline. They can easily capture, annotate, and attach photos of non-compliant items for more accurate reports. Confined space risk assessments can be sent immediately right after the inspection to any member of the organization with a single tap of a finger.
iAuditor by SafetyCulture is an award-winning management platform which allows teams to generate real-time reports on mobile devices while on-site. With iAuditor, you can easily evaluate confined spaces and capture hazards for immediate resolution. Get started with these free customizable confined space safety checklists:
Carlo Sheen Escano
Carlo Sheen Escano is a contributing writer for SafetyCulture based in Makati City, Philippines. Sheen has experience in digital marketing and has been writing for SafetyCulture since 2018. His articles mainly discuss risks in the workplace and well-known safety and quality processes used to mitigate them. Furthermore, Sheen is passionate about providing insights to global customers on how technology can help them to do the best work of their lives.
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