The incident occurred at Prime Recycling on Watson Street in Lenoir. Emergency crews evaluated 22 people at the site, and 14 were transported to UNC Caldwell for further medical assessment. All of those exposed are expected to recover, officials said.

The exposure also triggered a precautionary lockdown at an urgent care clinic in neighboring Burke County after one affected employee sought treatment there, authorities said.

Fire officials said the workers began experiencing respiratory problems shortly after the powdery substance was released from boxes being processed at the plant. The facility handles a high volume of returned and unwanted merchandise, a workflow that frequently involves opening sealed packages of unknown contents.

"It's one of those we don't want to see anybody hurt," a Lenoir Fire Department official said. "And I'm sure they'll have changes to their plant process about opening boxes. But the big thing is, hopefully nobody has any lasting effects from whatever they were exposed to."

Investigators are still working to determine what the substance was. No additional information about its origin or composition was immediately available.

The incident highlights the hazards facing workers at recycling and returns-processing facilities, where sealed packages can conceal chemicals, powders or other materials that become airborne when containers are opened. Workplace safety advocates have long urged employers in the waste and recycling industry to adopt screening protocols and protective equipment for employees who handle unverified shipments.

Prime Recycling did not immediately respond to questions about its safety procedures or whether operations would be paused during the investigation.