Ambulances responded Tuesday morning to a chemical plant in downstate Elwood for a reported "chemical incident" at the location.
A Will County hazardous materials crew and 10 ambulances were on the scene of Stepan Chemical Company in the 22000 block of West Millsdale Road, about 10 miles south of Joliet.
County Emergency Management Director Harold Damron said a valve opened and released therminol, a heat transfer liquid.
Though nothing spilled, a vapor was created and 18 contracted workers were exposed.
As of 10 a.m., the ambulance response was upgraded, and the exposed workers were being checked. No serious injuries were reported.
It wasn't immediately clear what led to the incident, Damron said.
