Originally Published: November 19, 2009 9:54 p.m.
In my last column I said that a carbon monoxide detector is a good idea in a home with any gas or woodburning appliances. I had several calls and emails regarding these detectors.
Shirley called and said she had been checking on the carbon monoxide detectors in the local stores. She said every one she found would not sound the alarm until the carbon monoxide levels were 70 ppm (parts per million). She asked what levels were safe, and if I knew of a detector that would go off at lower levels.
The Environmental Protection Agency (EPA), the Consumer Product Safety Commission (CPSC), and other public and private organizations, say that prolonged exposure to carbon monoxide levels over 70 ppm can be health concerns. Exposures to levels over 150 ppm are major health concerns, and can even be fatal after prolonged exposure. This is why most carbon monoxide detectors sound the alarm at 70 ppm. There are detectors that detect lower levels, but they are more expensive and are usually intended for specialized applications.
One obvious source of carbon monoxide is automobile exhaust. This is why doors and walls between homes and attached garages are supposed to be "gas-proof," including weatherstripping and self-closers on the doors. You should never warm up a car in a garage without opening the overhead door. Actually, I have read that newer cars usually require only a minute or two to warm up, unlike the cars in my youth with carburetors and heat-activated chokes.
There are other sources of carbon monoxide in a home.
The CPSC states there are an average of 170 deaths each year in the United States from "non-automotive consumer products." Any type of flame will produce some amount of carbon monoxide. This is why all woodburning and most gas appliances should be vented to the exterior of the home. Usually the only unvented gas appliance in a home will be the cooking range, although there are also unvented gas fireplaces (the topic of my last column). A gas cooking range will produce a little carbon monoxide when in use, and in fact even some vented gas appliances can put a little carbon monoxide in the room when they first come on.
Jack called me and said he had been feeling ill for the past month, just about the time he started using his gas furnace and fireplace. He wanted to know about the symptoms of exposure to carbon monoxide.
Exposure to lower levels of carbon monoxide can easily be confused with getting a cold or the flu - headache, fatigue, nausea, and possibly shortness of breath or mild dizziness. These symptoms should clear up once you are away from the carbon monoxide. Exposure to levels over 150 ppm can cause the same symptoms, and also vomiting, dizziness/loss of coordination, or confusion/disorientation. (I suppose these symptoms could be confused with drinking too much of your favorite adult beverage).
Note that people with health or breathing problems can be more susceptible to carbon monoxide poisoning. I told Jack that if he noted these symptoms after using his furnace or fireplace he should contact a heating company immediately to check his gas appliances.
I was also asked about how many carbon monoxide detectors you should put in your home, and where they should be located. Ideally you should put one in all the areas that require smoke detectors: in and just outside each sleeping room, at least one on each level of the home, etc. I don't have carbon monoxide detectors in every bedroom in my home, but I do have one in the halls outside the bedrooms and one on the other side of the home. Always follow the manufacturer's instructions and recommendations when installing carbon monoxide detectors - for example avoid direct sunlight, drafts, humidity, etc.
I always try to get a chuckle or two out of you in my columns (sometimes I succeed at this unintentionally). This has been a pretty 'serious' column, so I'll leave you with something I find mildly amusing.
I have been asked many times about building codes. Recently someone sarcastically asked me how we managed to survive 100 years ago, before there were building codes. I told him building codes have been around for a lot longer than 100 years. One of the oldest known building codes is found in the Codes of Hammurabi from around 2200 B.C. You should refer to this any time you get frustrated with our building codes:
section 229. If a builder has built a house for a man and has not made strong his work, and the house he built has fallen, and he has caused the death of the owner of the house, that builder shall be put to death.
section 230. If he has caused the son of the owner of the house to die, one shall put to death the son of that builder.
section 231. If he has caused the slave of the owner of the house to die, he shall give slave for slave to the owner of the house.
section 232. If he has caused the loss of goods, he shall render back whatever he has caused the loss of, and because he did not make strong the house he built, and it fell, from his own goods he shall rebuild the house that fell.
section 233. If a builder has built a house for a man, and has not jointed his work, and the wall has fallen, that builder at his own cost shall make good that wall.
Randy West owns Professional Building Consultants in Prescott. He is a state-certified home inspector and has performed almost 5,000 home inspections in the Prescott area. West is past president of the Arizona Chapter of the American Society of Home Inspectors (ASHI), and currently serves on the Home Inspector Rules and Standards Committee for the Arizona Board of Technical Registration. Contact him at email@example.com.