In recent years the push to install CO detectors in homes has resulted in them being required in many jurisdictions and certainly any jurisdiction that has adopted the 2009 or later IRC Building Codes will require them in New Construction. Washington State currently requires them on each floor level and in the vicinity of each sleeping area when a home is sold. In most homes this means there will typically be two of the devices but with large sprawling homes with basements and/or multiple stories there could be several more.
CO detectors for residential construction must meet the requirements of UL 2034.
What is not commonly understood about these detectors and UL 2034 is that they are “not intended to alarm when exposed to long-term, low-level carbon monoxide exposures or slightly higher short-term transient carbon monoxide exposures, possibly caused by air pollution and/or properly installed/maintained fuel fired appliances and fireplaces.”
(please reread the previous quote and the information below VERY carefully as it is counter-intuitive)
Following these standards, the alarms are: 1, not “allowed” to alarm when CO is lower than 50 parts per million; 2, they are required to alarm within 50 minutes at levels up to 150 PPM; and, 3, they are required to alarm within 15 minutes at Carbon Monoxide levels up to 400 PPM.
What the standards do not address is the fact that some individuals are greatly affected by being exposed to lower levels of CO over a longer period of time.
The Kidde user’s guide states: “While anyone is susceptible, experts agree that unborn babies, small children, senior citizens and people with heart or respiratory problems are especially vulnerable to CO and are at the greatest risk for death or serious injury.
INDIVIDUALS WITH MEDICAL PROBLEMS MAY CONSIDER USING WARNING DEVICES THAT PROVIDE AUDIBLE AND VISUAL SIGNALS FOR CARBON MONOXIDE CONCENTRATIONS UNDER 30 PPM.”
They go on to state: CO alarms provide early warning of the presence of carbon monoxide, usually before a healthy adult would experience symptoms.
So does this mean that those most in need of protection are not in fact protected?
Other alarm makers have similar recommendations.
This next caution from Kidde is very important, as I can attest to, from an incident at a recent inspection: “CAUTION: THIS ALARM WILL ONLY INDICATE THE PRESENCE OF CO GAS AT THE SENSOR. CO MAY BE PRESENT IN OTHER AREAS.”
When I turned on the oven at the inspection and it had been operating for just a couple of minutes, I started to experience some of the symptoms of CO poisoning. (Once you have experienced these symptoms you can almost become your own CO detector---but unfortunately human beings sleep, and then there is the problem that you might not notice very low levels of CO and thus be no more effective than UL 2034.) My “real” CO detector found over 600 PPM and yet the CO detector plugged in at the countertop on the other side of the kitchen did not go off and would not (under UL 2034) be required to go off until the unit experienced 400 ppm for as much as 15 minutes. Depending on air currents in the home, the unit might never see appropriate levels---even after the person using the stove succumbed to the gas.
The biggest concern that I have with all of this information is: “Who reads the instructions?” Are we creating an awareness of CO detectors where people are assuming they are protected when they in fact are not? While I still think installation of these alarms is probably a good idea, and that perhaps more appropriate residential CO detectors may be forthcoming, I think it is at least as important to better educate people to recognize the symptoms associated with Co poisoning as well as to be aware of what these detectors do and don't do.
Again from Kidde: “Be aware of the symptoms of carbon monoxide poisoning: – headaches, dizziness, weakness, sleepiness, nausea, vomiting, confusion and disorientation.
Recognize that CO poisoning may be the cause when family members suffer from flu-like symptoms that don’t disappear but improve when they leave home for extended periods of time.”
Carbon Monoxide in homes is a serious issue, and legislation/codes do not adequately address all the concerns associated with it. It is in all likelihood dangerous to assume that they do---if we and our families are to be safe in our homes. This is especially true as homes become tighter in relation to becoming more energy efficient.
Charles Buell, Real Estate Sales in Seattle
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WA State, Home Inspector Advisory Licensing Board