According to the Kyunghyang Shinmun, a joint inspection of the fire that broke out on the 16th at a metal injection and printing factory in Ojeong-gu, Bucheon, Gyeonggi Province, began at 9:30 a.m. on the 17th. About 20 people from four bodies took part: the Gyeonggi Nambu Provincial Police Agency, fire authorities, the National Forensic Service and the Korea Electrical Safety Corporation. They focused on the third-floor thinner cleaning area believed to be where the fire began.

Investigators are giving the most weight to the possibility that toluene in the thinner vaporized and that static electricity or frictional heat produced a spark that ignited the vapor. Kim Hyo-seong, head of the agency's forensic science unit, said a spark during the transfer of metal parts after washing is considered the most likely trigger. This is an estimate based on findings so far, not a confirmed cause.

No explosion-proof equipment where vapor could build up

The Kyunghyang Shinmun and the Hankook Ilbo reported inspectors' remarks that, although vapor could be generated at the site, no explosion-proof equipment or related safety facilities appeared to be in place. NewsWorks noted that occupational safety rules call for explosion-proof electrical equipment in such workplaces and reported that no anti-static devices were found either.

Conditions on site are also thought to have fed the blaze. Dozens of thinner containers sat one to two meters from the ignition point, some with their lids off, and hundreds of paint cans were stacked nearby, which may have helped flames and smoke spread quickly. How fast the fire spread, trapping the firefighters who went in first, is also part of the inquiry.

The building's safety net was thin as well. At 362 square meters, the factory fell below the floor-area threshold that makes sprinklers mandatory, so it had none. Large amounts of flammable materials, including Class 4 hazardous substances such as second-category petroleum products, were found, yet the business had no record of a permit to handle hazardous materials.

Small-site blind spots and the direction of the probe

Police are investigating whether hazardous materials were stored and managed unlawfully. They plan to confirm the exact composition and quantity of the flammables to determine whether this amounted to unpermitted handling. NewsWorks reported that a dedicated team has been formed to examine safety violations and illegal storage.

Experts say the current approach of exempting facilities from fire-equipment duties based on floor area alone should be reviewed. Proposals cited by NewsWorks include tiered management according to stored quantities, minimum explosion-proof gear and first-response firefighting tools regardless of building size, and a nationwide survey of unpermitted storage with joint inspections by local governments and agencies.

Investigators will send cleaning solution collected at the scene to the National Forensic Service for analysis. The precise cause and responsibility are expected to be determined after those results and the police investigation. The basic facts of the fire are unchanged from the previous day's report; whether the findings lead to broader debate on industrial safety rules remains to be seen.