A toxic gas leak at POSCO's stainless steel factory in Pohang, South Korea, resulted in one death and three injuries on the morning of November 5.

The accident occurred around 9 a.m. at the annealing and pickling plant while four subcontractors from POSCO DX were preparing for equipment maintenance. All four suffered breathing difficulties and chest pain after inhaling the suspected toxic fumes.

Tragically, one worker died after being hospitalized. The three other workers sustained first and second-degree burns but have since been released.

The fire authorities suspected the leaked chemicals were nitric acid or hydrofluoric acid. POSCO immediately halted the line for safety checks. Police are investigating the factory's safety managers to determine the exact cause of the fatal incident.