Cannock Police have placed a cordon around Chasewood Park Business Centre, Hednesford, and Staffordshire Fire and Rescue Service is at the scene.
Cannock Police tweeted on Wednesday evening: "We are currently at the scene of a suspected chemical incident at a business premises in Heath Hayes, Cannock.
"A cordon is in place around the Chasewood Park Business Centre on Hednesford Road as a precaution."
Police officers have also been sent to search properties in Hednesford in connection with the incident.
Cannock Police added: "We are also carrying out searches at a property on View Street, Hednesford, and at business premises on Wolverhampton Road, Cannock.
"Officers and colleagues from Staffordshire Fire and Rescue Service are at the scene."
