A discharge of the chemical hydrogen sulfide at a Pemex refinery in Deer Park on Thursday killed at least two refinery workers and injured at least 35 others, prompting a shelter-in-place order for adjacent homes that lasted much of the evening, according to authorities.
“We don’t know if there could be more (deaths),” stated Harris County Sheriff Ed Gonzalez. “We just haven’t been able to make entry into the unit itself.” He also stated that it could take another seven or eight hours for the highly toxic gas to evaporate for workers to safely carry bodies to the Harris County Institute of Forensic Sciences.
Hydrogen sulfide is a toxic gas with an odor similar to rotten eggs. It is present in crude oil and is a byproduct of the refining process. As it evaporates, the gas combines with oxygen to generate similarly foul-smelling sulfur dioxide, a far less toxic chemical that remains dangerous in high concentrations.
Pemex Deer Park acknowledged that the gas leak happened at 4:40 p.m. in one of the refinery’s operating units and that the problem was limited to the industrial complex.
Throughout the evening, police flares and roadblocks on Texas 225 warned drivers of potential danger. The traffic was heavy as cars, including a La Porte Independent School District bus transporting students, rushed to find alternate routes. Emergency vehicles from various Houston-area agencies blared sirens and honked their way across the highway’s thin shoulders.
According to TxDOT, traffic on Texas 225 was stopped down in both directions at Beltway 8.
In the early evening, residents at a Shell station on Center Street waited barely over a block away from the plant, seemingly unconcerned about the ongoing situation. A woman’s voice, transmitted over loudspeaker, ripped through the night. “Shelter in place, shelter in place, a gas leak has been detected,” the message read.
During a late Thursday news conference, Deer Park Mayor Jerry Mouton said that the shelter-in-place order had been withdrawn after Harris County Pollution Control air monitors discovered “nothing has gotten out into our community.”
Mouton agreed that the odor permeated the community to the point where neighbors had been contacting CenterPoint all evening to report what they believed to be gas leaks. He asked them to stop: “We’re not aware of any gas leaks.”
Officials from Deer Park’s Office of Emergency Management initially notified residents that the incident was “contained within the Pemex facility,” but then issued a shelter-in-place order for all city residents “out of precaution” before lifting it a few hours later.
Pasadena issued its shelter-in-place order for all areas north of Spencer Highway within the city borders, although it was withdrawn before Deer Park’s.
Harris County Judge Lina Hidalgo stated that the county’s Fire Marshal’s Office and Pollution Control Services were “on the scene to assist and monitor the air,” while the Harris County Office of Homeland Security and Emergency Management was ready to assist as needed.
“Our primary concern is to ensure the leak has stopped and that the leaked materials are not impacting county residents,” Hidalgo said to the press.
Gonzalez stated that his agency would oversee the probe. The event occurred in a facility controlled jointly by Pemex, Mexico’s state-owned oil firm, and Shell. Pemex operates the refinery, while Shell operates the petrochemical complex.
Shell Oil Co., a US subsidiary of Royal Dutch Shell, held the refinery for more than 90 years before selling it to Petroleos Mexicanos, or Pemex, in 2022. “Some people in the community may witness flare-ups while we carefully contain the situation. “We are closely monitoring air quality and have not detected any offsite effects,” Pemex spokesperson Raveena Moyes said in a statement regarding the chemical incident. Pemex has not commented on the sheriff’s reported injuries or deaths.
The company’s most recent community notification, posted at 5:26 p.m., stated that the refinery was “performing activities that may result in flaring,” but that they were unaware of any impact on the community or industrial neighbors. It made no mention of harmful gas discharge.
The alert was issued on the “CAER Online” website, which is used by local industrial enterprises to disseminate emergency information to the general public.
Shell later stated on the platform that an issue “occurred at another company within the boundaries of the complex” and that the Shell petrochemical facility was “doing a controlled slow down as a precaution.”
The corporation explained that the event concerned only its industrial neighbor.