The "white powdery substance" discovered in an envelope at Daley Plaza Tuesday morning turned out to be drywall dust, according to a Cook County spokeswoman.
Chicago Police and Hazmat crews were called at about 9:57 a.m. to investigate the suspicious substance apparently found by a staffer, News Affairs said.
A worker in the Vital Records office, located in the Pedway, opened an envelope filled with the powder, according to Courtney Greve, a County Clerk spokeswoman.
The staffer notified a supervisor, who called 911, Greve said in an email. The office was quarantined by Hazmat crews, she said, but was declared under control in about a half hour.