DePaul University issues mandatory mask Mandate indoors.

Chicago has issued a mask advisory. DePaul University is going back to making masks mandatory indoors effective immediately for employees in conjunction with CDC and CDPH updated guidelines.

All employees (student and professional) of Housing must begin wearing masks while in DePaul buildings immediately.

Recently, Cook County was added to the list of counties seeing "substantial" transmission Thursday. Other Chicago-area counties in that same category include: Will, DuPage, Kendall, McHenry, Boone, Winnebago, DeKalb, LaSalle and Grundy.

The universities mask mandate comes as over 100,000 concertgoers attended the Lollapalloza concert this past weekend.