Asphyxiation is not one of the addenda on the standard real estate “offer to purchase,” nor is carbon monoxide (CO) testing a part of many home inspections. You can’t see CO and you can’t smell it; it is not a visual defect and it’s therefore not part of the Standards of Practice of ASHI. But I still adore my Bacharach Monoxor II CO detector. I think of it as a magic wand; I point the end of the long, hollow sampling tube at a furnace or boiler, read the digital output and perhaps help save a life. Regardless of home inspection practices, your house, current or future, can still kill you; though actual deaths due to CO asphyxiation number just over a thousand per year, there are probably many thousands who suffer from symptoms caused by chronic or acute exposures to CO in their homes and places of work.
Since another heating season is beginning, I will share a few CO stories this month. Perhaps some of you recall a December 12, 1991 Boston Globe story about Stephen C. Brooks, a Burlington, Vermont real estate agent who sold his house in 1988 to a family of four after his own family was hospitalized by CO fumes from a malfunctioning boiler in the garage. Despite warnings from the gas company and a plumber, Brooks sold the house without repairing the boiler; three members of the new homeowner’s family died. In a precedent-setting case, the State of Vermont convicted Brooks in 1992 on three counts of involuntary manslaughter.
Combustion products from burning oil, gas or any other fuel are colorless gases that are supposed to go into a chimney and out of a house. Leakage of combustion products into a house is called “spillage,” and occurs commonly from boilers, furnaces, and even chimneys. Spillage gases are colorless and usually consist mostly of carbon dioxide and water vapor, but under some circumstances, carbon monoxide is also present. This is why any thorough home inspector will look for signs of spillage on a home inspection.
Spillage can be detected with a mirror or a combustible gas detector. In two homes this month, I observed spillage from boilers. In one case, the gases were exiting from the boiler between the cast iron combustion chamber and a thick coating of asbestos boiler cement. The boiler was an antique and should have been in a scrap yard, not a home. The concentration of CO in the spillage gases was over 500 parts per million (ppm), a level high enough to kill someone in an hour if inhaled directly. Since the defective boiler could not be repaired without disturbing the asbestos, I recommended that it be replaced. In another home where the Monoxor II meter went off scale at 2000 ppm, I actually become ill just from standing over the combustion gas plume while taking my measurement.
Heating systems are not the only source of CO. Water heaters, portable fuel-fired space heaters, gas stoves, grilles, and cars can be sources of CO in homes. It is common to find CO in homes and apartments above or attached to garages. Just starting a car in a garage and opening a door to the home briefly can cause elevated interior levels that might prove troublesome to sensitized individuals. Movement of CO (and fuel vapors) from garages into habitable spaces is a good reason to be sure that all openings in a garage ceiling under a home are well sealed.
If you have a friend buying a new home, a carbon monoxide detector makes a fine house warming present. You can get one in any hardware store; pick up a fire extinguisher for the kitchen at the same time. So what if they think you’re neurotic!