At 8.04am on 25 August last year, Darnell Alboudoor watched a plume of black smoke blanketing the sky and rolling in the direction of her family home. A stench like burning oil filled the air on that piping hot summer morning, as Alboudoor, 54, looked in the direction of the sprawling petroleum refinery, which sat a few hundred feet from her back yard.

She called 911. “I’m just wondering what’s going on over there,” she told the operator. “Nobody tells us nothing.

” “They’re handling it,” the operator responded. “Nothing to worry about.” There was no need to evacuate, Alboudoor was told, as she expressed her concerns over the fumes.

“I just want to know why we weren’t aware of this,” Alboudoor said. “Why are we just finding out about it now?” Unbeknownst to Alboudoor and the thousands of other south-east Louisiana residents who lived next door, the facility had been leaking for more than 13 hours. A storage tank containing at least 26,000 barrels of the flammable hydrocarbon naphtha had been on fire for about an hour and a half.

Twenty-six minutes before Alboudoor’s 911 call, a state environment official had recorded an alarmingly high reading of toxic air pollutants at a location on the plant’s fence line. But there had been no alert. No blaring sirens.

No word from local emergency responders. It was an example, residents and experts say, of the embedded culture of secrecy surrounding the hundreds of chemical plants and refineries that domi.