Part of tank car melted after Ohio train derailment, NTSB says

March 2 (UPI) -- The National Transportation Safety Board said Thursday the fire that erupted after the East Palestine train derailment melted an important part of the tank cars that were filled with toxic chemicals.

Investigators found that three of the five tank cars carrying vinyl chloride had their aluminum covers melted by the fire. This may have prevented the pressure-relief devices from functioning as they were designed, the NTSB said.

"When a tank car is exposed to fire conditions and its contents are heated, the pressure inside the tank rises," the NTSB said. "This can lead to loss of tank shell strength and eventually a breach."

The agency said that the cars with aluminum protective covers were made in the 1990s, and that it was unable to determine how many of these cars remain in operation.

The Environmental Protection Agency said last week that it was ordering a pause on the shipment of hazardous material from East Palestine.

Now, though, EPA region 5 administrator Debra Shore said the operation to transport hazardous waste from the site will resume soon. The decision comes after the agency received complaints from states where the waste was to be transported to, NPR reports.

Shore said all routes and disposal sites for contaminated waste will be subject to EPA review and approval.

According to Shore, the EPA has conducted 574 home re-entry screenings as of Saturday and is continually monitoring the air quality in East Palestine. She said there have been "no exceedances" of air quality standards and outdoor air quality is normal.

"One thing that's been made clear to me is that everyone wants this contamination gone from the community," Shore said. "We owe it to the people of East Palestine to move it out of the community as quickly as possible."