There are 3 types of carbon monoxide detection sensors: biomimetic, semiconductor, and electrochemical. Biomimetic sensors use color change in the presence of the gas for detection. Semiconductors measure change in resistance in a silicon chip when the gas is present. Electrochemical sensors send an electronic signal when a chemical reaction occurs in the presence of carbon monoxide.
While all these systems will detect CO, electrochemical sensors are the most accurate and sensitive of the detectors and are used in professional equipment. These are commonly found in relatively inexpensive detectors for purchase such as those from First Alert. The life of an electrochemical sensor is typically 3 – 5 years.
Because carbon monoxide is lighter than air, detectors should be located at least 5 feet above the ground. They should also be placed at least 10 – 20 feet away from furnaces or other fuel burning sources and 10 feet away from high humidity areas such as bathrooms. The alarm limits of detectors are set at relatively high levels to prevent false alarms such as those caused by cigarette smoke, so when an alarm sounds, it is best to move quickly to a well ventilated area or outside and to contact emergency personnel.
The above question was answered by Mark J. Bogard, CIH, Vanderbilt Environmental Health & Safety/ Chemical Safety Section
We had so many questions about CO detectors that it became necessary to track down an expert. Thanks to Mark Bogard! CDC web sites recommend that the product has the UL seal on it, has some type of battery back up and is used according to the directions.
A recent article in Consumers Reports indicated that less than 50% of homes contain CO detectors. What a potential for disaster! Educate your patients.
Next Week: Neuropsychiatric Sequelae following CO exposure.
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Donna Seger, M.D.
Tennessee Poison Center
Poison Help Hotline: 1-800-222-1222