Blast at Osaka Factory: Explosion and Chemical Blaze Leaves Four Workers Severely Burned, Area Evacuated

Osaka, Japan— Four industrial workers were left severely burned after a factory explosion triggered a chemical blaze in Osaka on October 22, 2026.

The explosion hit at 11:05 a.m. inside a chemical processing plant in the Konohana industrial zone. Workers were heating a solvent batch in a reactor when pressure spiked. A relief valve failed to open. The vessel ruptured. Flammable vapor filled the room and ignited, sending a fireball through the workshop.

The blast blew out windows and buckled metal doors. Inside, four men working within five meters of the reactor were engulfed. Co-workers in adjacent bays pulled them out and used safety showers to cool burns. The plant’s fire suppression kicked in but could not control the chemical fire.

Osaka city fire brigade arrived with six engines and a chemical unit. They found a pool fire under the reactor and thick black smoke containing irritants. A 200-meter evacuation was ordered for neighboring factories. Foam was used to smother the fire while water cooled adjacent tanks.

“These are high-temperature operations. The batch record shows temperature rose fast. Operators tried to vent manually but ran out of time,” said a plant supervisor outside the cordon. He said the reactor was 15 years old and inspected in August.

The four injured were taken to Osaka University Hospital’s advanced burn center. Doctors said all have burns over 50 percent of their bodies and inhalation injuries. Two are in critical condition on ventilators. Two are serious but stable.

Air monitoring showed elevated volatile compounds near the site but below dangerous levels beyond 300 meters. Residents were told to stay indoors for one hour. No off-site injuries were reported.

The Osaka Labor Bureau and the prefectural police have opened investigations. Logs, sensor data and maintenance records have been seized. The company has suspended operations in that unit and said it will cooperate.

The fire was declared under control after three hours. The reactor is destroyed. The site remains locked and under guard.