The incident began on Tuesday when the rail car, owned by the company INEOS, started venting the hazardous chemical, raising concerns over the potential for an explosion.

By Wednesday morning, officials from the Central Railroad of Indiana, the railroad company that owns the tracks, confirmed that the rail car had ceased venting styrene. However, first responders continue to douse the car with water to ensure it remains cool, as overheating could still trigger an explosion. Little Miami Fire Department Chief Mike Siefke announced during a noon press conference that despite the cessation of the venting, roads would remain closed and evacuations would persist due to the unresolved risk.

Mike Miller, a spokesperson for Central Railroad of Indiana, explained that a failed stabilizer additive was the likely cause of the venting. According to Miller, the rail car followed its safety design by venting the chemical when it overheated instead of exploding. Despite the car now solidifying the styrene and being in a safer temperature range, continuous monitoring is essential to prevent any resurgence in heat.

The INEOS site in Addyston, located approximately four miles from the venting site, is known for its polymer production, a history dating back to 1953 when it was under Monsanto before INEOS acquired it in 2007. While officials confirmed the rail car was in transit to a location a few miles away, the exact destination and the train's origin remain undisclosed. Details on the precise chemical composition of the failed additive stabilizer or why it malfunctioned were also not provided.

At the press conference, residents, eager for answers about the timeline for returning home, voiced their frustrations. Some claimed they had noticed the smell of the chemical days earlier, though the venting incident was officially reported at 1 p.m. Tuesday. As officials work to fully secure the area, the community remains in a state of cautious alertness.