An unknown white substance released from recycled material at a Waunakee recycling company sickened 13 workers, with officials not knowing what the substance was.
The incident happened around 11:50 p.m. at the Advanced Disposal site on Raemisch Road, the Madison Fire Department said.
The department's hazardous incident team was called to assist Waunakee EMS after multiple people reported getting sick when the white substance was released while materials were being sorted.
Monitors used by the haz-mat team didn't pick up any type of material to determine what had been released, and there was none of the substance on any clothing that the affected workers were wearing, the Fire Department said.
"Surveillance video was reviewed and it was evident that whatever substance might have been in the sorting line had been processed and packed for transport," said MFD spokeswoman Cynthia Schuster.
The affected package was removed from the building.