Carbon Monoxide, an in-the-home killer

Jan. 9, 2011 - PRLog -- The NFPA (National Fire Protection Association) estimates 480 deaths occur annually from carbon monoxide (CO) poisoning relating to exposures from non-fire causes.

Those deaths relate to hazards involving motor vehicle exhaust, home heating equipment, cooking appliances and engine-driven equipment such as lawn mowers, generators, etc.

Annually, over 60,000 non-fire carbon monoxide incidents are reported to responding fire departments, with nearly 90 percent of these incidents occurring in the home.

Carbon monoxide is formed as a result of an incomplete combustion process, which involves all carbon-based fuels, such as propane, oil, natural gas, wood and coal.

Under ideal combustion conditions, a fuel's carbon molecules mix with air's oxygen molecules to form carbon dioxide; however, if lack of oxygen is present, deadly carbon monoxide is formed.

Carbon Monoxide and Oxygen Starvation
The molecules of the red blood cells, hemogoblin, which normally attach to the oxygen molecules to form oxyhemogoblin will combine instead with carbon monoxide to form carboxyhemoglibn. This process starves oxygen to the vital tissues, such as the brain.

Inhalation of carbon monoxide can affect one's memory and thinking, which in turn, leads to dizziness, fatigue and confusion. Carbon monoxide can kill within minutes.

Breathing air with only a 1.3 percent concentration of carbon monoxide will almost immediately cause unconsciousness and possible death in one to three minutes.

A concentration of carbon monoxide in air just below one-fifth of one percent can cause nausea within 20 minutes and death within an hour.

Serious non-fatal exposure to CO is marked by symptoms of memory loss and confusion, with possible resulting permanent brain damage and total disability.

The Occupational Safety and Health Administration (OSHA) requires a carbon monoxide exposure limit based on an eight hour average day of no more than 50 parts per million or 5/1000 of one percent.

CO and its Attributes
CO is very difficult to detect since it is odorless, colorless and tasteless. Low levels of carbon monoxide exposure generally result in headaches, dizziness, overall weakness, nausea and other flulike symptoms.

Prolonged exposure to low levels of CO can result in permanent brain damage and total disability.

A Defective Venting System
A major cause of CO entering living spaces is a defective venting system. To discuss this danger, let's first look at the fundamentals of a venting system for gas-fired appliances.

A draft is defined as the flow of exhaust gases and air through a chimney or flue pipe to the outside.

Natural draft is developed by the temperature difference between the hot gases exiting the gas-fired appliance and the surrounding cooler, ambient air.

Hot gases are lighter than the surrounding air and that weight or density difference creates buoyancy, like a cork in water.

The heavier surrounding ambient air descends downward and around the appliance, which forces the hot vented gases upward through the flue pipe and/or chimney.

To facilitate these buoyant conditions effectively, sufficient amounts of cooler ambient air surrounding the appliance are necessary, both for proper combustion and draft. When the venting system is not functioning properly, vented gases are most likely, backing up into the living space, a condition known as back drafting.

Combustion Air
For complete burning, a natural gas appliance requires 10 cubic feet of air for every one cubic feet of gas burned. During combustion, natural gas, CH4, ignites with air containing oxygen, O2, and nitrogen, N2, to produce heat, light, water vapor, carbon dioxide, CO2, and nitrogen. If insufficient air is available for combustion, CO is produced, instead of CO2.

Along with the combustion requirement, additional ambient air is needed to surround the venting gases to produce a draft necessary to move the hot gases up the flue pipe and/or chimney.

The air required to produce both complete combustion and to facilitate adequate draft is referred to as combustion air.

Confined Space
The requirement for adequate combustion air is defined by NFPA 54, National Gas Code, which states a confined space is a space where its volume is less than 50 cubic feet per 1,000 Btu/hour of total input ratings of all appliances in the space.

If the space meets the criteria as a confined space, the Code requires two air openings be provided for combustion air to enter the confined space. Each opening is to be sized based on the requirement of 1,000 Btu/hour of total input ratings of all appliances in the confined space.

The top opening is to be within 12 inches from the top of the space, and the lower opening is to be within 12 inches from the bottom of the space.

Carbon monoxide poisoning caused by lack of combustion air tends to involve very confined spaces, such as a closet or small utility room containing a gas-fired furnace and a gas-fired hot water heater. If these conditions are present, CO tends to be produced erratically and therefore, it may be difficult to measure CO levels using a CO meter.

One means to determine the extent of a CO problem involving a confined space having, for example, gas-fired appliances inside a small utility room, such as a furnace and water heater, is to check the levels of CO in each appliance's vented gases.

Generally, a lack of combustion air will cause the appliance's burners to soot and clog resulting in poor combustion and high levels of CO in its vented gases.

Our firm has been called upon for several carbon monoxide poisoning matters involving gas-fired appliances being installed in confined spaces. Those matters were successfully investigated and resolved prior to trial.

Issues with Chimneys and Flue Stacks
Plugged or partially plugged chimneys or flue stacks can result in back drafting and CO entering the living space. One primary cause is animals nesting in the flue stack or chimney. The most effective preventative measure is installing flue or chimney caps.

Another cause of CO entering a living space is a chimney or vent pipe, which was constructed from single-wall galvanized sheet metal. Over time, the metal will rust and/or separate at its connections, resulting in cracks for CO to escape.

These flue pipes are especially dangerous if they were installed in concealed spaces, for example, between walls or nailed-off attics.

The National Gas Code, as far back as the 1960's, prohibited single-wall metal flue pipes from originating in any unoccupied attic or concealed space and passing through any attic, inside wall or floor that is concealed.

Our firm has investigated two matters involving the use of single-wall vent pipes that were installed in concealed spaces. Those pipes had corroded and separated, resulting in CO entering the living spaces and killing the inhabitants.

Carbon Monoxide Detectors
An excellent prevention tool is a CO detector, preferably installed in a hallway near the bedrooms.

Today's detectors meet current Underwriters Laboratory Standard, UL 2034, and are designed to sound an alarm only when detecting dangerous concentrations of CO.

A carbon monoxide detector will assist in providing an advanced warning before very dangerous CO concentrations are incurred. Their cost is usually less than $50.

Summarizing
CO is a very deadly gas. Breathing air containing just over one percent CO causes almost immediate unconsciousness and death within minutes.

To prevent CO poisoning in your home involving your home's fuel heating equipment, annual checks need to be conducted. Such checks should include, for example, the furnace, space heater, water heater, fireplace, wood stove, etc. and are recommended before the beginning of the winter heating season.

Also, these checks need to ensure the flue pipes are tight and not corroded, and the chimney is clear of any debris. Also, if you do not have a CO detector in your home, please install one as soon as possible.

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Russell Fote & Associates, Inc. provides expert witness, forensic consulting and testimony services for plaintiff attorneys, defense attorneys and insurance company claims departments. Expert Safety Engineer. At Russell Fote & Associates, our purpose is to provide our clients with the very best safety engineering and expert consulting services.

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