Thousands of residents near the site of a US train derailment and toxic gas leak were still barred on Tuesday from returning to their homes four days after the accident.
Officials “out of an abundance of caution” closed schools near the derailment in East Palestine, a small community in northeastern Ohio on the border with Pennsylvania.
Odor and haze were reported over the area as the Norfolk Southern railway prepared further controlled releases of toxic vinyl chloride gas from several still-smoldering tanker cars.
A one-mile by two-mile mandatory evacuation zone remained in effect around the 150-car derailment site.
Authorities warned residents outside the evacuation zone to shelter in their homes if at all possible.
“We are asking that you… only go outside if absolutely necessary,” the Springfield Township Fire & Rescue Department said in a statement late Monday.
“The vinyl chloride contents of five rail cars are currently unstable and could potentially explode,” said a statement on the website of the office of Ohio Governor Mike DeWine.
The statement, released Monday afternoon, said Norfolk Southern planned “a controlled release” of the trapped gas to burn it off but that it could release fumes that are “deadly if inhaled.”
Vinyl chloride is a colorless gas used in a variety of plastic products and packaging materials. When burned it can create phosgene, a highly toxic substance used as a chemical weapon in World War I.
The mandatory evacuation zone comprises areas in both Ohio and Pennsylvania.
“It is unknown when residents will be able to return to their homes but an announcement will be made when it is safe to return,” the Ohio governor’s statement said.
The cause of the derailment is still under investigation.
