Investigation records and statistics compiled in the immediate aftermath of a serious industrial accident are filled with phrases pointing to individual fault — "worker carelessness," "a misstep," "improper operation." But the accident-cause assessments written by inspectors at the Korea Occupational Safety and Health Agency and now open to the public tell a different story. The direct causes lay in engineering defects in the equipment itself and in safety systems that lacked any mechanism to prevent accidents.
The Ministry of Employment and Labor has been publishing accident investigation reports on its website since May, ahead of the June implementation of the amended Occupational Safety and Health Act. The reports released cover 51 serious accident cases that occurred in 2024 and for which court rulings have become final. The Seoul Economic Daily analyzed seven fatalities that took place at manufacturing worksites.
In one case, a permanent employee at Company A, a plastic container manufacturer in Hwaseong, Gyeonggi Province, was crushed to death between molds in June 2024 while inspecting the inside of a blow molding machine. A high-frequency oscillation proximity sensor, designed to halt operation when the inspection door was opened, was installed at the top of the door. The sensor detects changes in the magnetic field when a metal object comes within 5mm, registering whether the door is open or closed.
A joint investigation by the agency and police found a magnet 2cm in diameter on the surface of the left proximity sensor. With the magnet attached, the sensor lamp stayed lit even when the door was open, so the machine did not stop. On its face it appears that the worker attached the magnet, but the engineering analysis points to a defect in equipment management. Plastic melt molding machines are built such that a full shutdown, followed by cooling and reheating, results in the loss of raw material and hours of downtime. With product temperatures rising and defects a concern, there was no authority to halt the line and no standard operating procedure for doing so.
Weaknesses also emerged in the safety equipment standards. The report identified as core defects behind the accident the decision to leave a simple proximity sensor — one easily bypassed with an ordinary magnet — in place as an interlock safeguard; the failure to install an anti-defeat switch or physical latch that cannot be released without a dedicated key; and the absence of a Lock Out-Tag Out (LOTO) system for cutting power and applying locks during maintenance. Unaware that the door was open, the machine narrowed the gap between the left and right molds, which extends to a maximum of 1.3 meters, to 33cm, crushing the worker.
A roof fall in February at Company B, a chemical fertilizer manufacturer in Asan, South Chungcheong Province, also stemmed from physical defects in the walking environment. A daily-hire worker dismantling an aging skylight on a warehouse roof 4.7 meters above the ground fell to the floor and later died while receiving hospital treatment. Agency inspectors measured the site and found that the spacing between screw holes in the steel channel beams serving as supports on the roof was 91cm. That is 17cm wider than the 74cm average stride of South Korean men in their 40s and 50s, as recorded in a paper published by the Ergonomics Society of Korea. On a roof pitched at nine degrees, the worker could move only by stretching out more than 17cm beyond a normal stride. The skylight the worker stepped on after losing balance was just 1 to 1.13mm thick. The aging plastic skylight, installed in 2016, could not bear the load and broke, causing the fall.
The impact force on the human body in a fall from 4.7 meters is roughly 2,906 kilograms, exceeding the 200-kilogram limit the human skull can withstand. Yet none of the basic fall prevention measures — work platforms, safety nets or anchorage for safety harnesses — were in place. The analysis concludes that the fall was caused not by worker error but by an environment designed to exceed the limits of the human body.
A fatal entrapment in an automatic stacker in April at Company C, a concrete block manufacturer in Hwaseong, Gyeonggi Province, combined an algorithm error in the control system with defects in safety barriers. When agency inspectors reconstructed the accident on site, they confirmed a programming error: if a single brick was missing near sensor No. 1, the conveyor would carry bricks beyond the prescribed six rows, up to a maximum of 12.
At the time of the accident, seven rows of bricks entered and sensor No. 2 detected them, stopping the machine. With the cubing machine left in automatic mode and its power still on, the operator removed the seventh row of bricks. As sensor No. 2 stopped detecting them, the cubing machine registered conditions as normal and began its descent. The worker, bent forward to clean the floor, was pinned between the cubing machine body and the conveyor. The equipment qualified as an "industrial robot" under the Occupational Safety and Health Act. Yet there was no 1.8-meter safety barrier to block entry into its range of motion, and no interlock linked to an access gate. A gap 0.6 meters wide had been left as a passage between the barrier and the conveyor. There was no presence-sensing safeguard to protect workers in the event of a malfunction.
The same pattern held at Company D, a machinery installation contractor in Seosan, South Chungcheong Province. There, a contract worker was crushed to death by equipment that toppled over while a heat exchanger was being moved out. The investigation found the plate heat exchanger measured 79cm wide and 140cm high and weighed 390 kilograms. But it was asymmetrical, with roughly 80% of its weight concentrated on the right side where the plates were. With three base plates 95mm in diameter that had anchored it to the floor removed, it stood on just three supports 20mm thick, maximizing the risk of tipping. In a cramped space measuring 135cm by 150cm, the dangerous practice of moving the heavy object with a 1.5-meter crowbar, without bracing to prevent it from toppling, continued.
An entrapment in a shredder at Company E, a single-ingredient feed manufacturer in Jeongeup, Jeonbuk State, was also a preventable accident. The direct cause was the layout of the control panels. A manager asked to move a crane's grab pressed the wrong switch, starting the shredder. The shredder's local control panel, installed directly alongside the crane control panel, carried no label identifying the load it served and no start or stop markings. The report found that a defect in equipment management — the failure to attach identifying labels to a control panel added on an ad hoc basis in 2010 for convenience — induced the human error.
At Company F, a recycled plastic manufacturer in Hwaseong, Gyeonggi Province, 600-kilogram ton bags — the oversized sacks used to hold raw material — were stacked two high without pallet racking to prevent them from tipping. The worksite assigned forklift transport in a cramped storage yard to a daily-hire worker without preparing a work plan for handling heavy objects or verifying that the worker was qualified. When a damaged pallet tore the lower ton bag, the worker was patching the gap with duct tape when the upper bag lost its balance, toppled and crushed the worker to death. At Company G, a corrugated cardboard manufacturer in Seo-gu, Incheon, a worker in their 70s who was securing netting from the bed and cab roof of a one-ton truck caught a foot on a roof rack and fell to their death. Despite the work being performed at height, the worker was provided with neither anchorage for a safety harness nor a hard hat.
All seven accidents occurred during non-routine tasks — inspecting, repairing or clearing errors on operating equipment, and loading and unloading. Every report concluded that administrative measures such as reminding workers to stay alert cannot block human error. They called for adopting fail-safe systems in which the equipment itself is designed to guard against human mistakes: installing anti-defeat interlocks that physically stop machines when doors open; mandating LOTO systems that cut power and apply locks during maintenance and repair; providing work platforms at least 30cm wide, sized to account for human stride, along with fall protection nets; installing 1.8-meter barriers around industrial robots; and adding bracing and pallet racking to keep heavy objects from toppling.
Sharing detailed accident information is essential to identifying mechanical defects in equipment and prompting worksites to invest in prevention. Ryu Hyun-chul, head of the ministry's Occupational Safety and Health Headquarters, wrote on his Facebook page that "for the Occupational Safety and Health Headquarters, the proper way to mourn and pay tribute is to do our job properly," adding that "companies, researchers and workers must be able to see these reports so that serious accidents do not happen again."
