The owner of a West Des Moines business said a loose pipe on his furnace is to blame for poisoning 11 of his employees.
The carbon monoxide poisoning happened Monday at A.F. Johnson Millwork on Railroad Avenue in West Des Moines.
MidAmerican Energy was called out to test the building Monday afternoon. Readings were in the triple digits.
Firefighters said that even double-digit readings are dangerous.
Of the 11 people sent to the hospital, seven came to Iowa Methodist Medical Center's hyperbaric center.
Four people chose to be treated inside a hyperbaric chamber that essentially pushes the poison out of a person's body.
Ryan Andrew's lab results showed his blood carried 21 percent carbon monoxide, instead of oxygen.
"Well, I was experiencing flu-like symptoms, cold sweats all over, nausea and just your vision starts to go weird on you," Andrew said.
Business owner Hank Evans said he did not have carbon monoxide detectors, but he's getting them now.
