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Confined space safety: Don't take it for granted

Updated: Mar 13

During the past week, a number of members of the American Society of Safety Engineers (ASSE) group on LinkedIn have been having a spirited discussion about the subject of confined space safety. Specifically, how deep does a trench need to be in order to be considered a confined space? As little as one foot, says one safety manager - about the average width of the human torso. If someone was lying down installing plumbing fittings, in such a trench, they could be overcome by fumes. According to OSHA, any open-top space more than 4 ft. deep with limited means of entry and egress may be considered a confined space. Another safety professional reminds us that the term "confined space" can cover many different types of restricted work environments: "Potentially any structure in which people work could be or could become a confined space. Confined spaces can be very large or they can be very small. What the term actually describes is an environment in which a broad range of hazardous conditions can occur. These conditions include personal confinement, as well as structural, process, mechanical, bulk or liquid material, atmospheric, physical, chemical, biological, safety and ergonomic hazards." The danger of an enclosed space has very little to do with its depth, but much to do with the gases that may be leaching through the soil and into the trench, causing oxygen to be displaced. Even a shallow trench may have high levels of carbon dioxide, hydrogen sulfide or xylene, which can be fatal to workers exposed to them. The LinkedIn group concluded that every confined space needs to be evaluated before a worker enters it, regardless of depth. If the type of work may expose workers to potentially harmful gases, then instruments should always be used to measure the levels of oxygen and other gases present in the environment prior to anyone entering the space. Interested? See: Confined Space for Construction.

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