Ypsilanti, MI – A carbon monoxide leak sent one resident of an Ypsilanti apartment house to the hospital and displaced the others early Wednesday morning, officials said.

The Ypsilanti Fire Department was called to a seven-unit apartment building in the 100 block of East Cross Street at 1:51 a.m. after receiving reports of an unknown odor.

One of the residents was suffering from dizziness and a headache, said Ypsilanti fire Captain Dan Cain. That resident was transported to the hospital.

“The levels they had in there were critical,” Cain said.

Officials will evacuate a building that has carbon monoxide levels of 35 parts per million. The levels at the East Cross apartment building was 500 parts per million.

“It was in the deadly zone,” Cain said.

A faulty furnace was to blame, Cain said.

A faulty furnace was to blame, according to fire officials. Stewart Beal, who owns the property, is putting up the displaced residents at the Harmony House Hotel until the furnace can be fixed.

Beal said the boiler flue was clogged and it was being cleaned out Wednesday. Beal did not have any information about the resident taken to the hospital. There were seven residents in the apartment house.

Dr. Mark J. Lowell, Associate Professor of Emergency Medicine at the University of Michigan Medical School, gave The Ann Arbor News some background and symptoms of carbon monoxide.

“CO is an odorless and colorless gas that is a byproduct of incomplete combustion,” he said in an email. “Exposure can lead to very nonspecific sympoms, including headache (most common), nausea, malaise, and dizziness.”

The nonspecific nature of the symptoms leads people to incorrectly diagnose themselves as having the “flu,” or some other type of viral syndrome, according to Lowell.

Higher levels of exposure can lead to changes in mental status, fainting, seizures and ultimately coma.

In young children who can’t complain of symptoms, watch for feeding difficulty and fussiness, Lowell said.

Common sources are faulty heaters, but exposure can result from poorly ventilated generators and garages.