High carbon monoxide levels prompt evacuation at South Shore building

High levels of carbon monoxide prompted an evacuation at a nine-story apartment building early Saturday in the South Shore neighborhood.

A Level 1 HazMat response was called at 3:07 a.m. at the building in the 7100 block of South South Shore, according to the Chicago Fire Department. It was upgraded to Level 2 HazMat at 3:22 a.m.

Carbon monoxide levels were recorded at 300 parts per million, according to CFD Cmdr. Curtis Hudson. Further investigation revealed that the elevated levels were caused by a boiler that wasn’t ventilating properly.

All of the building’s units were evacuated and all residents were brought down to the lobby, Hudson said. They were allowed back into their apartments by 5:06 a.m. after crews ventilated the building and repaired the problem with the boiler. No injuries were reported.