Nearly two dozen people were hospitalized in the 30 hours following an overnight chlorine gas leak outside the Dow Hydrocarbons complex, the Iberville Parish president said Thursday.
An Olin Chemical production unit leaked liquid chlorine that quickly vaporized into the air after a compressor caught fire at 8:38 p.m. Monday, forcing residents to shelter in their homes for more than three hours. Roads were also closed at the time.
The fire, the leak and the leak suppression by emergency officials led to a large plume of gas and smoke to rise up and away from homes along the southern boundary of Dow's 1,500-acre chemical complex, officials have said.
But emergency responders still reported that the chlorine had escaped to the south toward residents in Plaquemine during breezy conditions. The heavier-than-air gas can meander along the ground.
On Tuesday and Wednesday, Olin officials reported "no injuries" from the leak. But Iberville Parish President Mitch Ourso said 23 residents went to Ochsner Medical Complex-Iberville in Plaquemine because of the leak and most went the day after, on Tuesday.
Ourso said parish officials were not informed about the extent of the residents' ailments from the leak.
"They had the opportunity, you know, if they felt they needed, to go the emergency department at the Ochsner facility," he said.
Olin officials haven't yet commented on the hospital visits, first reported by WBRZ on Thursday, since a call for a response from The Advocate. Olin owns units inside Dow's operations, including the chlorine production facility the leaked the toxic gas.
Greg Langley, spokesman for the state Department of Environmental Quality, said agency officials were not aware of the hospital visits and were surprised to learn of them on Thursday.
Langley said that people absolutely have the right to seek medical care but agency officials stand by their determination that the off-site chlorine gas emissions were not at a concentration that reached what they called an "action level."
Parish officials previously have said the detections south of the Dow complex had reached no higher than 1 part per million.
DEQ officials said they stopped detecting off-site releases by 6:15 a.m. Tuesday, though some fence line detections were still occurring at low concentrations.
Residents living near the complex who didn't immediately shelter in their homes reported a strong chlorine smell on Monday night.
One part per million is equivalent to about one cup of water in a swimming pool, according to the U.S. Environmental Protection Agency.
In short-term exposures of a few minutes to a few hours, chlorine is far from lethal and hardly a significant health risk at 1 part-per-million or less. That takes concentrations tens of times higher, but even an exposure of four hours to a part-per-million of chlorine can induce an asthma-like attack in some people, a handful of studies have shown.
According to an Environmental Protection Agency fact sheet, exposure to chlorine can irritate the eyes, upper respiratory tract and lungs. At higher levels, it can cause chest pains and vomiting. It is extremely irritating to the skin and can cause severe burns with high enough exposure.
Langley, the DEQ spokesman, added that DEQ officials aren't ready to comment about how much chlorine was released in the incident.
In an eight-month period in late 2016 and later in 2017, Olin's operations inside Dow had three chlorine leaks that injured a contract worker and prompted employee evacuations and road closures. But emergency officials said at the time they never posed a risk to the public.
One of the leaks, in December 2016, stemmed from a massive power outage that Entergy later said was triggered by the burning of sugar cane. The other leaks in September 2017 were caused after four electrical rectifiers tripped.
Companies that have significant emergency pollution releases must provide a report to DEQ within seven days with an initial estimate of what escaped. Sometimes these reports aren't available in DEQ's records database for several days after they are submitted, however.
Often, companies provide these reports even when the amount ends up being less than what would normally trigger the reporting requirement.
Olin officials have promised to determine the root cause of the release, an effort that usually examines whether the incident was preventable and can take months.
Chlorine gas leaks are among several worst-case risks surrounding Louisiana petrochemical industry, which relies on the element — sometimes made by breaking up the chemical components of brine extracted from the state's salt domes — to help make plastics and variety of other chemicals necessary for modern conveniences.
In 2020, Hurricane Laura triggered a fire and vast plume of greenish-grayish smoke at the BioLab Inc. complex, releasing an unknown amount of chlorine gas that blanketed Lake Charles.
Most of the city's residents had evacuated prior to the hurricane, and no serious injuries were reported.
The Dow site straddles Iberville and West Baton Rouge parishes. Located along bend in the Mississippi River, Dow is one of Louisiana's largest petrochemical facilities, with more than 3,000 company and contract employees and 12 production units, the company has told regulators.