After a deadly battery factory fire, attention turns to the safety of migrant workers

Choi, the labor attorney, questioned how airtight the company's safety training could have been.

"Would what they call routine safety training have been of any use for day laborers?" he said. "It's a system that is fundamentally flawed because it's not like they can redo all the safety training every time someone new comes in."

Lithium batteries can combust from moisture, external impact or faulty manufacturing, making fires an ever-present threat for which manufacturers should be prepared, experts say.

Aricell's product — a military-grade, nonrechargeable battery — was especially dangerous, according to Park Chul-wan, a battery expert at Seojeong University.

Used for portable military devices like walkie-talkies, the batteries contain a chemical called thionyl chloride, which is preferred for its high energy density. But if vaporized in a fire, the chemical is highly corrosive to the eyes, skin and throat.

"It makes the window to get to safety incredibly short," Park said. "The moment the room fills with this vapor, anyone would instantly panic and fall to the ground."

Lithium battery fires are exceptionally difficult to put out. Because temperatures can quickly reach more than 2,000 degrees, standard extinguishers or even water from sprinklers won't work.

The best hope, according to Park, is an overwhelmingly large volume of water, or a specialized fire extinguisher graded for metal fires.

But in South Korea, the provision of these special fire extinguishers isn't mandated by law. And although the company has said that it had several of these extinguishers on the premises, they were not the ones the workers had at hand.

Outside the smoldering factory, a family member of one of the migrants who died threaded his way through the fire trucks until he was stopped by a group of reporters.

"What is this?" he said. "Safety should have been observed. We foreigners are made to do the lowest form of labor. How can this stand?"