From the Minneapolis Star-Tribune.
A St. Paul couple were in critical condition after they were found unconscious in bed Tuesday afternoon, victims of what fire officials suspect was carbon monoxide poisoning from a malfunctioning boiler...
The house was inspected by Xcel Energy, Zaccard said, and it appeared that the flue was blocked, backing up exhaust gases in the home, perhaps for some time.
Carbon monoxide (CO) is a colorless and odorless gas that can accumulate in the blood and deplete it of the ability to carry oxygen. At sustained concentrations above 150 to 200 parts per million, it can cause disorientation, unconsciousness and death, according to the U.S. Consumer Product Safety Commission.
When firefighters entered the house Tuesday, they detected carbon monoxide levels at 300 parts per million, Zaccard said.
When they got to the boiler, he said, levels were "well in excess" of 850 parts per million, the maximum level that the firefighters' equipment can measure.
"By far, it's the most serious case we've had for this winter," he said, adding that St. Paul firefighters average about one call a day about dangerous carbon monoxide levels.