5 killed, 8 hospitalized in toxic gas accident at Vietnam pig farm

Doctors said the victims fell prey to the 'slaughterhouse sledgehammer effect,' in which people lose consciousness within seconds after inhaling high concentrations of the gas in enclosed spaces.

Bach Mai Hospital's Ninh Binh campus in Ninh Binh Province, northern Vietnam, admitted the eight injured workers after the accident occurred at a biogas pit on a pig farm operated by Dabaco Thanh Hoa Co., Ltd. in Thach Quang Commune, Thanh Hoa.

The eight workers were taken to the hospital after five of their coworkers died at the scene from inhaling a high concentration of hydrogen sulfide gas.

The accident began at around 5:30 pm on Saturday, when a male employee of the company slipped and fell into a biogas pit, losing consciousness.

His coworkers rushed into the pit one after another to rescue him, while others leaned over the pit opening in an attempt to pull him out, all without protective equipment.

The rescue effort quickly turned into a chain-reaction accident, with multiple workers collapsing at the scene.

As a consequence, five workers died at the scene, while eight others were hospitalized.

Upon admission to the hospital, all eight patients were conscious and reported headaches, while some also had conjunctival irritation and congestion, lactic metabolic acidosis, and rhabdomyolysis.

They remained under close observation at the hospital's Poison Control Center.

Dr. Nguyen Trung Nguyen, director of the center, said the victims were exposed to hydrogen sulfide inside an enclosed waste storage pit measuring about two meters by two meters by three meters, with an opening slightly wider than one meter.

He explained that hydrogen sulfide is an extremely toxic gas whose poisoning mechanism is similar to that of cyanide, rapidly disrupting cellular respiration.

The gas is particularly dangerous in confined spaces such as biogas pits, wells, wastewater tanks, sewers, and enclosed compartments on ships.

He added that the condition is known in medical literature as the 'slaughterhouse sledgehammer effect' because victims can lose consciousness almost instantly after inhaling the gas.

At low concentrations, hydrogen sulfide has the distinctive smell of rotten eggs.

At higher levels, however, it can paralyze the olfactory nerves, preventing people from detecting the odor and leaving them unaware that they are inhaling the toxic gas.

“Many people mistakenly believe that deaths in biogas pits are caused by methane. In reality, hydrogen sulfide is responsible for many of these rapid fatalities,” Dr. Nguyen said.

The Poison Control Center urged the public never to enter confined spaces such as biogas pits, storage tanks, deep wells, or sewers without proper ventilation and appropriate protective equipment.

If someone is found unconscious inside a confined space, rescuers should not instinctively rush in after the victim, the center warned.

Instead, only properly equipped personnel should enter while others remain outside to assist.

If toxic gas is suspected, the area should first be ventilated by opening access points and using fans or pumping fresh air into the confined space before anyone enters.

Doctors emphasized that prompt medical treatment during the 'golden hour' is critical to improving victims' chances of survival following toxic gas poisoning.

On Sunday, Cao Van Cuong, deputy chairman of the Thanh Hoa administration, inspected the accident scene and ordered a comprehensive investigation into the cause of the accident.

He also requested a thorough inspection of the pig farm's operations, including its compliance with construction, environmental, and wastewater treatment regulations.

Cuong instructed the company to strengthen workplace safety measures to protect employees and personnel involved in the investigation and recovery efforts.