Carbon Monoxide Poisoning
In the United States, an estimated 80,000 people seek medical help as a result of exposure to high levels of carbon monoxide. Most poisonings occur in winter, when consumers crank up furnaces and fireplaces and have windows closed tight. For many homeowners, it comes as a surprise that new appliances in a new house may not be safe.
You need to recognize the warning signs so you can take steps to ensure your family is safe from carbon monoxide poisoning — a poisoning that is preventable. The following information will help you determine what steps you should take to prevent CO poisoning. You will learn how to recognize the signs of carbon monoxide in your home, physical symptoms produced, and what to do about it.
WHAT IS CARBON MONOXIDE
Carbon monoxide is composed of a single molecule of carbon and one of oxygen, abbreviated CO. Carbon monoxide is an invisible, colorless, odorless, tasteless, and lethal gas — the by-product of incomplete combustion. It's a silent killer that can sneak under doors and through walls. The gas is released into the air when fuels like natural gas, oil, or wood do not burn completely in appliances such as furnaces, wood stoves, water heaters, space heaters, ranges, ovens, and clothes dryers. Any fuel-burning appliance in your home can be a potential CO source. Using charcoal indoors, portable kerosene and gas heaters, fireplaces, or running a car in an attached garage can also create dangerous levels of carbon monoxide.
Children, whose bodies are still developing, are more susceptible to the effects of poisons than those of healthy adults. Children can be affected by CO gas before adults even show symptoms.
PHYSICAL SYMPTOMS
Absorbed through the lungs, carbon monoxide combines with hemoglobin, which normally carries oxygen to the body's cells. Carbon monoxide replaces oxygen in the bloodstream causing hypoxia, an abnormal reduction of oxygen in the body tissues also called oxygen deficiency. Exposure to carbon monoxide can cause any of these flu-like symptoms: headaches, nausea, fatigue, dizziness, drowsiness, burning eyes, irregular breathing, confusion, disorientation and unconsciousness. In very severe cases, carbon monoxide poisoning can cause brain damage (sometimes permanent) or death. As length of exposure and amount of carbon monoxide increase, so does the severity of the symptoms, up to and including unconsciousness and death.
Low-level exposure to carbon monoxide produces flu-like symptoms and can cause headache, fatigue, shortness of breath, nausea, dizziness, short-term memory loss and behavioral changes. Because symptoms of carbon monoxide poisoning mimic the flu, the concern is that poisoning cases are not being diagnosed. In most CO poisoning cases, you will have symptoms of the flu without a fever present. When members of an entire family begin to suffer profound headaches, weakness and nausea, this may be a good time to visit your doctor. Ask your doctor for a CO blood test. Children and the elderly will show symptoms of CO poisoning before a healthy adult. If a flu bug is persistent, and family members are sick sporadically, this may be an indication of CO poisoning. Also be alert if members of the household have these symptoms at home, but feel better away from home, then CO or other pollutants in the home may be suspected.
Long-term exposure to low levels of carbon monoxide leaves people feeling constantly run-down, with headaches, dizziness or flu-like symptoms.
CARBOXY-HEMOGLOBIN
CO binds tightly and rapidly to hemoglobin and crowds out oxygen. As CO combines with oxygen, it forms carboxy-hemoglobin (HbCO). Carboxy-hemoglobin stifles the release of oxygen into the cells from normal hemoglobin. As little as one part of CO in 1,500 parts of air can convert half of the body's hemoglobin to carboxy-hemoglobin.
Normal carboxy-hemoglobin levels are 0% to 3% for nonsmokers and 3% to 8% for smokers. Levels of 10% to 20% (mild toxicity) may cause headache, nausea, vomiting, visual disturbances, confusion, dizziness, irrational behavior, and difficult or labored breathing.
Levels ranging from 30% to 40% (moderate toxicity) may cause severe headache, brief loss of consciousness, fainting, and tachycardia (high heart rate).
Severe toxicity (over 40%) can cause seizures, respiratory failure, coma, convulsions, and death from severe cellular hypoxia (oxygen deficiency).
The most characteristic sign of CO poisoning is a cherry colour of the skin and mucous membranes due to the bright red colour of carboxy-hemoglobin.
WARNING SIGNS
Because carbon monoxide results from improper burning or venting, be alert to signs indicating a problem.
SYMPTOMS MAY INCLUDE:
Decreasing hot-water supply.
The pilot light of a furnace or other gas-fired equipment keeps going out.
The pilot light and burner flames of a gas furnace or other gas-fired equipment are mostly yellow, rather that clear blue. (Please note that some natural gas fireplaces are designed to have yellow flames).
A furnace unable to heat the house or one that runs constantly.
Soot buildup around appliance vents.
Black streaks on walls or around baseboard radiators.
Stale or stuffy air.
Unfamiliar or burning odor.
You notice a sharp, penetrating odor or the smell of natural gas when your furnace or other natural gas equipment turns on.
High humidity.
Increased condensation inside windows.
Rusting or water streaking on vents and chimneys.
Chalky white powder residue on vents and chimneys.
Visible rust or stains on vents and chimneys.
Loose masonry on chimney.
Loose or missing furnace panel.
An appliance that makes unusual sounds or emits an unusual smell.
An appliance that keeps shutting off. Many appliances have safety devices installed that prevent dangerous operation of the unit. An appliance which constantly shuts off may be an indication that the appliance is not safe. Call a service repairman to test the appliance before you try to operate the unit again.
If you suspect that you are experiencing poisoning, get fresh air immediately. Open windows and doors for more ventilation, turn off combustion appliances and leave the house.
CALL 9-1-1 IMMEDIATELY.
TIPS ON PREVENTING CO POISONING
Be alert to symptoms of CO poisoning.
Have your contractor check the thermostat's calibration and dust its contacts.
Electric and natural-gas furnaces should be checked by a heating and air-conditioning professional each fall to be sure the entire heating and venting system and their supply hoses and connections are safe and in peak operating condition.
Consult a plumber or a heating contractor before attempting to disconnect or make changes to a natural gas appliance.
Have a professional inspect the fireplace and chimney system making sure all connections are tight and all pipes, vents and chimneys are free of obstacles chimney caps are secure flues are in good condition and free of debris check for dents in the chimney pipe and loose joints, rust-holes and corrosion on the flue pipe (the pipe that connects your furnace to the chimney) or on the furnace itself and check furnaces and stoves are drafting properly.
Examine vents and chimneys regularly for improper connections, visible cracks, rust or stains.
Never burn charcoal indoors or in a garage.
Make sure appliances are installed according to manufacturer's instructions and local building codes. Most appliances should be installed by professionals. Follow manufacturer's directions for safe operation.
Never service appliances without proper knowledge, skills, and tools.
Never use the gas range or oven for heating.
Never leave a car running in a garage.
Never operate a standing motor vehicle outdoors in close proximity to an air intake vent on a building.
Ventilate your house using mechanical ventilation that gives you a constant, controlled supply of fresh air.
Do not operate a snow blower or lawn mower in the garage or basement.
Never operate unvented gas-burning appliances in a closed room.
Never operate any fuel-burning device in a tent, trailer, or building without adequate ventilation, particularly at higher altitudes where the oxygen supply is more limited.
Install a carbon monoxide detector with a digital readout, preferably on every level of the home.
BACKDRAFTING
Backdrafting means the exhaust from fuel-burning appliances flows back into the house rather than up and out a flue or chimney.
Many water heaters, furnaces, boilers, and fireplaces are naturally drafted, which means they rely on the rise of hot air to move combustion gases up the chimney. When those gases cannot escape, the air vents back into the home. The use of household fans that exhaust air, such as the kitchen and bath fans or the clothes dryer or central vacuum system, can overcome that natural draft and cause appliances to backdraft.
Range-top fans can pull so much air out of the house that the draft necessary to carry the smoke up the fireplace chimney could reverse, filling the house with smoke and allowing dangerous gases to collect in the house. However, turning your range-top fan off is not the solution. Gas stoves are significant sources of carbon monoxide and tainted indoor air. A properly installed fan, one that is vented to the outdoors and not to the attic or basement, should be used every time the stove is used because it evacuates carbon monoxide from the gas stove. The solution is to have your home tested to gauge what is causing your home to back draft.
Another contributing factor to back drafting can be weather and wind conditions. When air is forced down the chimney, expelled air from the fireplace, furnace, or other fuel-burning appliances can no longer escape the home, resulting in back drafting.
SIGNS YOU HAVE BACKDRAFTING:
The fireplace will not work when the kitchen, bathroom, or clothes dryer fan is in use.
The home is more humid. There is excess moisture on the windows and walls.
Your ears pop when entering the house or opening doors or windows.
The air is stale.
There is an odor.
WHAT YOU CAN DO TO PREVENT BACKDRAFTING:
Have your home tested to learn how much air goes in and out naturally and whether air is coming from unhealthy sources such as the garage, basement or the attic. Test results can help determine the priorities for making necessary changes.
Install water heaters and furnaces that don't draft up the chimney (called sealed combustion units) the type that won't expel carbon monoxide when other appliances or exhaust fans are used. A small blower in a sealed furnace forces the flue gases outdoors.
Recirculating fans or fans vented into the attic or basement do not protect your home from carbon monoxide poisoning. Fans should always vent out of the home.
TYPES OF CARBON MONOXIDE DETECTORS
There are three basic types of CO sensors — biomimetic, metal oxide, and electrochemical. No matter which detector you choose, it's important to know where to install and how to maintain it. It's best to have one detector on each floor of a house. Be careful that they are not obstructed by furniture or draperies. If you plan to purchase only one alarm, install it in the hallway outside the sleeping area.
Detectors measure carbon-monoxide concentrations and exposure time. They are designed to sound an alarm before you're exposed to an unsafe level. Working much like home smoke detectors, carbon monoxide detectors will sound an alarm when levels within the home go beyond 10 parts per million for eight hours or 100 parts per million for five minutes. A level of 40 parts per million is considered dangerous.
Plug-in detectors with a digital readout of carbon monoxide parts per million rather than battery-operated units that simply sound an alarm is preferable. By checking the readout, resetting the alarm and checking again, you can determine whether there is a real problem.
BIOMIMETIC
Biomimetic is designed to mimic the way the body responds to carbon monoxide. Sometimes called chemioptic, the technology uses gel-coated discs that darken in the presence of CO, tripping the alarm. These detectors are inexpensive, requires so little electricity that it can be battery-powered, and won't sound the alarm in the presence of common household gases. These detectors are not as precise as the other technologies. High and low temperatures and humidity can trip these alarms. Biomimetic sensors excel when indoor relative humidity (40 to 60 percent) and temperature (60° F to 80° F) are controlled.
METAL OXIDE
Metal oxide, or tin oxide, semiconductor technology is the oldest of the sensor types. With this type, heated tin dioxide reacts with carbon monoxide to determine levels of the toxic gas. Because the tin oxide is heated every few minutes, the unit uses about 2 watts — more than 10 times the energy used by the other technologies. That means tin oxide is limited to plug-in detectors, which can be an advantage if you often forget to check batteries (all come with a battery backup for power outages). Metal oxide sensors respond quickly to CO, but may sometimes be tripped by common household chemicals. High humidity can also be a problem, sensors degrade slightly each time they are exposed to moisture.
ELECTROCHEMICAL
With electrochemical technology, the third type of sensor, three platinum electrodes in an electrolyte solution generate energy when they react with CO. This technology has been used in industrial detectors for more than 20 years. These detectors respond quickly to CO, but their sensors have a short life. Electrochemical is a dangerous technology when unchecked. The sensor can go dead and you would never know it. Sensor replacement is required every two years. Electrochemical detectors are battery-powered and have a few more bells and whistles than the others, including a continuous digital readout, an LCD display, and a memory feature that allows you to check CO levels that occurred in your absence.
If your detector indicates a carbon-monoxide problem even after a reset check, call 9‑1‑1 and ask for help. If you suspect you are experiencing poisoning, get fresh air at once. Open windows and doors, turn off any fuel-burning appliances and leave the house. See a doctor immediately.
If it's a plug-in model, don't use an outlet controlled by a wall switch.
Keep detectors at least 10 feet distant from a fuel-burning appliance and away from most household chemicals or aerosols.
Detectors should not be located in dead-air spaces — crawl spaces, room corners, peaks of vaulted ceilings, or behind curtains — where CO might not reach.
Detectors should not be in areas of high air turnover, such as near a ceiling fan or a fresh air vent, which could mask CO buildup.
Do not install a detector in an area subject to wide temperature or humidity swings, such as an attic, garage, or bathroom.
Test your CO detector at least once a week.
Battery-operated detectors will warn you when power is low, but replace the batteries annually anyway.
CO detectors must meet the requirements of the most recent Underwriters Laboratories standard 2034 or the requirements of the IAS 6-96 standard.
Avoid using cardboard or plastic detectors that change color and do not sound an alarm. They require you to look at the device to determine if CO is present. CO concentrations can build up quickly while occupants are asleep, and these devices would not sound an alarm to wake them.
GARAGE EXHAUST
Although they look solid, garage walls are no barrier to combustion byproducts. Carbon monoxide seeps in from the garage into the house through the shared walls and ceilings. Exhaust gasses can seep into the house when a vehicle leaves or enters the garage or you start a snow blower or lawn mower, contaminating the air with carbon monoxide and air laden with dirt. Deaths have occurred in homes next to enclosed garages in which drivers have let their vehicle motors run. Car exhaust produces combustion byproducts resulting in ultra-fine coating of oily, sooty, black residue in your home. If you notice soot in your home, or your carpets are dirty — this could be the result of your car exhaust.
Do not run a vehicle, snow blower, or lawn mower inside a garage.
Do not let your car idle inside the garage to "warm-up". Take your car out of the garage away from any air intake vents on the building.
Seal and caulk the garage.
Add a carbon monoxide detector.
Install mechanical ventilation or an air-to-air heat exchanger.
If your CO detector's alarm is activated, and inspectors find no problem, advise the inspector of your car usage for that day. An alarm can be activated two hours after your car has left the garage.