By Kathy Gill & Jeffrey Zientek
Between 2011 and 2018, there were a reported 1,030 confined space deaths according to the Bureau of
Labor Statistics (BLS). That averaged out to about 100 deaths per year. It’s difficult to obtain accurate statistics for the period between 2019 and 2025 without extensive research. BLS reported 44 confined space deaths in 2022, and Purdue University reported 22 agricultural confined space deaths in 2024. However, that number may not include non-agricultural confined space deaths.
Regardless of the statistics, far too many people die each year in entirely preventable incidents. So, why are these tragedies still happening?
OSHA defines confined spaces as areas large enough for human occupancy, with limited ingress and
egress, and not designed for continuous occupancy. A permit-required confined space is one with a
known hazard, such as a hazardous atmosphere, restricted configuration, sloping or converging walls,
an engulfment hazard (grain, water, etc.), or any other recognized danger (unguarded machinery,
electrical hazards, heat stress, etc.).
Not all confined spaces are clearly identified with signage. For example, in 2017, three workers
entered a manhole to investigate why the street above was sagging. The first worker entered and was
immediately overcome by hydrogen sulfide gas in deadly concentrations. Two others attempted a rescue
but were also overcome. When firefighters arrived, one attempted entry but could not fit while wearing
his breathing apparatus. He removed it, expecting his partner to hand it down, but inhaled a single
breath of toxic gas and was instantly knocked unconscious. Fortunately, he was rescued and survived. The three workers, however, all perished.
In many confined space fatalities, more would-be rescuers die than the initial entrants. This is known as chain reaction death, and it often claims two to three additional lives. Between August 22 and August 27, 2025, nine people died in two separate confined space incidents in Colorado and Texas. Seven of the nine were attempting to rescue the original victim. It is difficult to imagine that, after one rescuer collapses, others would still enter, but in the chaos and urgency of the moment, the human instinct to help often overpowers rational safety decisions.
As a retired special operations fire captain from a major metropolitan fire department, Jeff has seen many confined space rescues and recoveries. What’s the difference? A rescue is an urgent entry where rescuers assume significant risk to save lives believed to be salvageable. A recovery is a slower, calculated operation after it has been determined that survival is no longer possible. While this decision feels callous, it is necessary to prevent additional deaths.
So why are people still dying in confined spaces? In addition to his fire service career, Jeff Zientek, trained emergency response teams (ERTs) for a large Texas manufacturing company handling exotic chemicals and numerous confined spaces. Team members, who held regular plant jobs, were trained in rope rescue, hazardous materials, trench rescue, and confined space emergencies. Employees were taught to recognize hazards, follow strict safety procedures, and use protective equipment. Worksites like this, with proper training and signage, rarely experience confined space fatalities. Knowledge and preparation save lives.
Most confined space deaths occur in areas not labeled or even considered “confined spaces.” Workers are often unaware of the hazards or lack the equipment to evaluate the environment. Examples include sewers, storm drains, crawl spaces, manure pits, silos, septic tanks, underground mines, caves, tank trucks, machinery compartments, wells, and cisterns. These places may exist on private property or even in everyday public spaces such as city streets. Have you ever seen a manhole marked as a “confined space”? It should be. More accurately, it should be labeled a permit-required confined space. Without clear labeling and education, people will continue to underestimate these dangers.
In an informal (and admittedly unscientific) assessment, we believe the most common confined space killer is hydrogen sulfide (H₂S), followed by carbon monoxide and then simple asphyxiants such as carbon dioxide and methane. H₂S is especially underestimated. It forms naturally when organic matter decomposes in oxygen-poor environments, meaning it isn’t stored in drums but develops in everyday places like sewers, alleys, or even drains in our homes. H₂S is both toxic and flammable, but it becomes lethal long before it reaches flammable concentrations. At 600–700 ppm, it can cause “one-breath knockdown,” and at around 120 ppm, it disables the sense of smell, leaving victims unaware of continued exposure.
The good news: H₂S and other deadly gases can be easily detected using inexpensive air monitors—if workers are equipped with them and trained to use them. Engulfment hazards, particularly in grain handling, are another major cause of fatalities. Workers attempting to unclog grain chutes often know the risks but continue anyway, perhaps relying on past successes. As the saying goes, “It’s fine—until it’s not.” Workplace safety, particularly important for industries such as construction, utilities, and manufacturing, where workers may encounter hazardous environments. These spaces, defined by OSHA as areas with limited entry or exit and not designed for continuous occupancy, pose significant risks, including poor air quality, engulfment, and entrapment. Proper training equips workers with the knowledge to identify potential dangers, utilize personal protective equipment (PPE), and execute emergency procedures effectively.
As of September 6, 2025, adherence to OSHA 29 CFR 1910.146 standards remains mandatory, underscoring the necessity of comprehensive programs that cover hazard recognition, atmospheric testing, and rescue protocols to prevent fatalities and injuries. The importance of confined space training extends beyond compliance, fostering a culture of safety and preparedness that protects both employees and employers. Well-trained personnel can respond swiftly to emergencies, reducing downtime and mitigating legal and financial liabilities. For instance, training on the use of ventilation systems, gas detectors, and rescue harnesses ensures that workers are not only aware of the risks but also capable of managing them. Advancements in safety technology, integrating hands-on simulations and regular refresher courses, are essential to keep skills sharp and adapt to evolving workplace challenges, ultimately safeguarding lives and enhancing operational efficiency.
Jeffrey Zientek is a retired fire captain with the City of Phoenix (AZ) and is the author of Hazmat Response: A Field Operations Guide. Jeffrey has and continues to instruct in special operations disciplines such as rope rescue, hazardous materials, confined space, helicopter rescue, & building collapse.
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https://hazmatresponseguide.com/
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