Have you ever considered the unique challenges and dangers of working in confined spaces? These areas might be small and restrictive, but they have considerable risks requiring special attention and care. Today, we will explore the critical issue of confined spaces and how to manage their hazards.
This post will explore what constitutes a confined space, the risks associated with working in such environments, and essential safety measures to protect yourself and your team. By the end, you’ll be well-equipped with the knowledge and tools to ensure safety when working in confined spaces.
What You’ll Learn
- Definition and Examples of Confined Spaces: Understand what qualifies as a confined space and where you might encounter them in various industries.
- Risks of Working in Confined Spaces: Learn about the specific hazards associated with confined spaces, including limited oxygen, toxic gases, and restricted movement.
- Safety Measures and Best Practices: Discover effective strategies and essential safety protocols for working safely in confined spaces.
Introduction
Confined spaces present many physical and environmental hazards to workers, with an estimated fatality rate between 0.05 and 0.08 per 100,000 workers (Selman et al., 2018). They can be any place that creates conditions that could risk health and safety and often include vessels, tanks, containers, pits, bunds, chambers, cellars, silos, drums, vats, or other similar spaces.
While we often consider confined space risks to be associated with the manufacturing, oil and gas (Naghavi et al., 2019), or construction industries, there are risks in other industries, too. A recent report published by Purdue University (Cheng et al., 2021) discussed 64 fatal and non-fatal confined space incidents in the agricultural industry in the United States.
What is a Confined Space
A confined space is any space that may:
- Have limited access and egress and is not designed for work
- Have an oxygen concentration that may be hazardous
- Have a flammable atmosphere
- Have toxic contaminants
- Cause engulfment.
Confined spaces are particularly hazardous because the atmospheric environment can change quickly and without notice. Since they are not a normal place of work, many confined spaces are used either for access to remote locations or to perform maintenance.
Considerations with Confined Spaces
When performing a confined space risk assessment, it is crucial to identify any potential sources or processes that may introduce contaminants. Some questions that may be asked include:
- Does the vessel contain water, or did it previously contain water? Is there a potential for sludge or fungal growth? (Plant matter will respire, consuming oxygen in the space).
- Is there any oxidation of the vessel walls? (Oxidation or rusting of the vessel walls also uses oxygen).
- Have any chemicals been stored in the vessel? What was the vessel used for previously? (Toxic chemicals may also be a potential source of risk).
- Are there any sources of flammable gases or vapors? Have incoming lines been blanked, the pipe removed, or locked out?
Before Entering a Confined Space
Before entering a confined space, the atmosphere should be tested for the concentration of oxygen, flammable gases, and toxic contaminants. Entry should not be permitted unless:
- The oxygen concentration is between 19.5 percent and 23 percent
- Explosive gases are not more than 5 percent of the lower explosive limit (LEL)
- Any toxic contaminants are less than their occupational exposure standard.
The LEL is the lowest level at which an explosion may occur if there is sufficient oxygen and an ignition source. If the concentration of the LEL is less than 5 percent, work in the space can continue. If the LEL is between 5 and 10 percent, the area must be continuously monitored, and if the flammable gas concentration is more than 10 percent, the area must be evacuated.
Summary
Confined spaces are potentially high-risk workplaces. Professional advice should be sought where required, and local regulations or industry standards should be consulted for further details of safe working procedures and recommended control measures.
Helpful Resources
- Confined Space Entry and Rescue, by CMC Rescue
- NFPA 350, Guide for Safe Confined Space Entry and Work, by NFPA
- Fundamentals of Industrial Hygiene, by Jill Niland and Lucy Elam
- Industrial Hygiene Monitoring Blog Post, by Megan Tranter
- Occupational Exposure Limits Blog Post, by Megan Tranter
Bibliography
Cheng, Y.-H., Nour, M., Field, B., Ambrose, K., & Sheldon, E. (2021, May). 2020 Summary of U.S. Agricultural Confined Space-Related Injuries and Fatalities. Purdue University. https://extension.entm.purdue.edu/grainsafety/pdf/2020_Confined_Space_Summary.pdf
Naghavi, Z., Mortazavi, S., Asilian, H., & Hajizadeh, E. (2019). Exploring the Contributory Factors of Confined Space Accidents Using Accident Investigation Reports and Semistructured Interviews. Safety and Health at Work, 10(3), 305-313. https://www.sciencedirect.com/science/article/pii/S2093791118304840
Selman, J., Spickett, J., Jansz, J., & Mullins, B. (2018). An investigation into the rate and mechanism of incident of work-related confined space fatalities. Safety Science, 109, 333-343. https://www.sciencedirect.com/science/article/abs/pii/S0925753517319574
