November 26, 2001

Public Service Announcement

To: Newsroom

For Immediate Release

Contact: Brian A. Crawford, Public Information Officer

Phone: 673-6652, cell: 455-2609, page: 675-2137

Frequently Asked Questions About Carbon Monoxide

• Part of the Shreveport Fire Department’s Preparing for Winter (PFW) series

What is carbon monoxide (CO) and why do I need a carbon monoxide detector?Carbon monoxide is a colorless, odorless, tasteless and toxic gas produced as a by-product of combustion. Any fuel burning appliance, vehicle, tool or other device has the potential to produce dangerous levels of carbon monoxide gas. Examples of carbon monoxide producing devices commonly in use around the home include:

• Fuel fired furnaces (non-electric)

• Gas water heaters

• Fireplaces and woodstoves

• Gas stoves

• Gas dryers

• Charcoal grills

• Lawnmowers, snowblowers and other yard equipment

• Automobiles

The Consumer Products Safety Commission (CPSC) reports that approximately 200 people per year are killed by accidental CO poisoning with an additional 5000 people injured. These deaths and injuries are typically caused by improperly used or malfunctioning equipment aggravated by improvements in building construction which limit the amount of fresh air flowing in to homes and other structures.

While regular maintenance and inspection of gas burning equipment in the home can minimize the potential for exposure to CO gas, the possibility for some type of sudden failure resulting in a potentially life threatening build up of gas always exists.

What are the medical effects of carbon monoxide and how do I recognize them?Carbon monoxide inhibits the blood's ability to carry oxygen to body tissues including vital organs such as the heart and brain. When CO is inhaled, it combines with the oxygen carrying hemoglobin of the blood to form carboxyhemoglobin. Once combined with the hemoglobin, that hemoglobin is no longer available for transporting oxygen. How quickly the carboxyhemoglobin builds up is a factor of the concentration of the gas being inhaled (measured in parts per million or PPM) and the duration of the exposure. Compounding the effects of the exposure is the long half-life of carboxyhemoglobin in the blood. Half-life is a measure of how quickly levels return to normal. The half-life of carboxyhemoglobin is approximately 5 hours. This means that for a given exposure level, it will take about 5 hours for the level of carboxyhemoglobin in the blood to drop to half its current level after the exposure is terminated.

The following table describes the symptoms associated with a given concentration of COHb:

% COHb Symptoms and Medical Consequences

10% No symptoms. Heavy smokers can have as much as 9% COHb.

15% Mild headache.

25% Nausea and serious headache. Fairly quick recovery after

treatment with oxygen and/or fresh air.

30% Symptoms intensify. Potential for long term effects

especially in the case of infants, children, the elderly,

victims of heart disease and pregnant women.

45% Unconsciousness.

50%+ Death.

What are the different types of carbon monoxide detectors and how do they work?There are a number of different types and brands of carbon monoxide detectors on the market today; They can be most easily characterized by whether they operate on household current or batteries. Underlying this, in most cases, is the type of sensor employed in the detectors operation. Detectors using household current typically employ some type of solid-state sensor which purges itself and resamples for CO on a periodic basis. This cycling of the sensor is the source of its increased power demands. Detectors powered by batteries typically use a passive sensor technology which reacts to the prolonged exposure to carbon monoxide gas.

Are some types of detectors better than others? How do I select the best detector for me?Regardless of the type of sensor used all detectors sold on the market today should conform to minimum sensitivity and alarm characteristics. These characteristics have been defined and are verified by Underwriters Laboratory in their standard for carbon monoxide detectors UL 2034. This standard was most recently revised in June of 1995 and went into effect in October of 1995. This revision specified additional requirements regarding identification of detector type, low-level (nuisance) alarm sensitivity and alarm silencing. Under no circumstances should one purchase a detector that is not UL listed.

Each of the two types of detectors mentioned previously has applications in the home along with associated advantages and disadvantages. The proper detector for each application or installation should be chosen based on the application requirements and the products specifications.

How many carbon monoxide detectors should I have and where should I place them?The Consumer Product Safety Commission recommends a detector on each floor of a residence. At a minimum, a single detector should be placed on each sleeping floor with an additional detector in the area of any major gas burning appliances such as a furnace or water heater. Installation in these areas ensures rapid detection of any potentially malfunctioning appliances and the ability to hear the alarm from all sleeping areas. In general, carbon monoxide detectors should be placed high (near the ceiling) for most effective use. Detectors should also not be placed within five feet of gas fueled appliances or near cooking or bathing areas. Consult the manufacturers installation instructions for proper placement of a detector within a given area.

Copyright 1995, H. Brandon Guest and Hamel Volunteer Fire DepartmentRights to reproduce granted provided copyright information and this statement included in their entirety. This document provided for informational purposes only. No warranty with respect to suitability for use expressed or implied.

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