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Carbon Monoxide
Carbon Monoxide: The Silent Killer

Carbon Monoxide: The Silent Killer What carbon monoxide is Where carbon monoxide is found Other producers of carbon monoxide Examples of actual poisonings Clues that may indicate a problem Health problems associated with carbon monoxide What to do in case of carbon monoxide exposure Decreasing exposure to carbon monoxide What Carbon Monoxide Is Carbon monoxide (CO) is an odorless, colorless, tasteless, and nonirritating gas. It is produced whenever carbon-based fuels are burned such as gas, oil, kerosene, wood, or charcoal. In addition to carbon monoxide, nitrogen oxides, sulfur dioxide and particulates, are also produced during combustion. Carbon monoxide may accumulate indoors as a result of tobacco smoking, poorly ventilated appliances, and attached garages. An estimated 1,500 people die each year because of carbon monoxide poisoning and thousands of others end up in hospital emergency rooms. At high concentrations, carbon monoxide can cause coma and death within minutes. Carbon monoxide enters the blood from the lungs and combines with hemoglobin, blocking the blood's ability to carry oxygen to body cells. Carbon monoxide poisoning is more common in northern-latitude and high-altitude states where people use home heating more due to cold weather. Alaska has the highest death rate from carbon monoxide poisoning and Hawaii has the lowest.¹ Where Carbon Monoxide Is Found Carbon monoxide has been found in offices, schools, restaurants, bars, arenas, and homes with gas appliances. The two most common causes of fatal or near-fatal carbon monoxide poisoning are misuse or malfunction of heating devices and motor vehicle exhaust. Elevated carbon monoxide concentrations are more likely in: Smaller multi-unit dwellings Households using gas ranges for cooking Dwellings heated by gas wall furnaces Vented appliances are appliances designed to be used with a duct, chimney, pipe, or other device that carry the combustion pollutants outside the home. These appliances can release large amounts of pollutants directly into your home if a vent is not properly installed, or is blocked or leaking. Unvented appliances, such as some space heaters, do not vent to the outside, so they release combustion pollutants directly into the home. If appliances are not vented or are not properly maintained, it can result in a build-up of carbon monoxide from these sources: Unvented or malfunctioning gas and oil furnaces Unvented kerosene or gas space heaters Unvented gas hot water heaters Unvented gas ranges Unvented gas clothes dryers Unvented gas boilers Wood or coal stoves Other Producers of Carbon Monoxide Carbon monoxide also can be produced by the following: Camp stoves. Camping lanterns. Gas-powered lawn mowers. Back-drafting from furnaces, gas water heaters, wood stoves, and fireplaces; gas stoves. Backdrafting is when the air pressure inside the home is less than the air pressure outside, causing combustion by-products from furnaces, water heaters, fireplaces and similar equipment to spill back into the room rather than being vented outside. Backdrafting can also occur when natural draft appliance exhaust is pulled back into the house by mechanical ventilation, such as a downdraft kitchen power vent. Environmental tobacco smoke. Cigarette users inhale four times the carbon monoxide found in car exhaust. Smoke from one pack can raise a home's carbon monoxide concentrations to twice the EPA safety limit for outdoor air. Car exhaust. This is usually a problem in attached-garages in the home or in parking garages. Though indoor air is the concern here, carbon monoxide levels have been measured in the blood of people exercising (like running or biking) in areas of heavy vehicular traffic. Malfunctioning or leaky chimneys used for wood, gas, or oil exhaust. Loading docks where improper ventilation or a leak in the ductwork, can let gas seep into a building. Offices, adjacent to warehouses with propane-powered forklifts. Methylene chloride vapors. Though methylene chloride (a volatile organic compound (VOC) used as a furniture stripper) does not give off carbon monoxide itself, the vapors are converted (metabolized) inside the body into carbon monoxide. As a result, one can suffer carbon monoxide poisoning from inhaling methylene chloride vapors. Using small gasoline-powered engines or tools in an enclosed space. Concrete saw operators, in particular, experience more severe symptoms of carbon monoxide poisoning. Other gas-powered equipment linked to occupational carbon monoxide poisoning include high-pressure washers, power trowels, floor buffers, welders, pumps, compressors, gas torches, forklifts, and generators. Workers using these tools in buildings or semienclosed spaces have been poisoned by carbon monoxide. Carbon monoxide can rapidly accumulate (even in areas that appear to be well ventilated) and build up to dangerous or fatal concentrations within minutes. This is because most people erroneously believe that an opened window or an operating fan defines a "well-ventilated area." In a study that measured the levels of carbon monoxide produced by a five-horsepower gasoline-powered engine, researchers found that hazardous levels of carbon monoxide were generated by these small engines in a matter of minutes?even in large areas with a lot of airflow.² Examples of Actual Poisonings A farm owner died of carbon monoxide poisoning while using an 11-horsepower, gasoline-powered pressure washer to clean his barn. He had worked about 30 minutes before being overcome. A municipal employee at an indoor water treatment plant lost consciousness while trying to exit from a 59,000-cubic-foot room in which he had been working with an eight-horsepower, gasoline-powered pump. The doors were open next to his work area while he worked. His hospital diagnosis was carbon monoxide poisoning. Five workers were treated for carbon monoxide poisoning after using two eight-horsepower, gasoline-powered pressure washers in a poorly ventilated underground parking garage. A plumber used a gasoline-powered concrete saw in a basement with open doors and windows and a cooling fan. He experienced a severe headache and dizziness and began to act in a paranoid manner. His symptoms were related to carbon monoxide poisoning. Clues That May Indicate a Problem Rusting or water streaking on vent/chimney Loose or missing furnace panel Loose or disconnected vent/chimney connections Debris or soot falling from chimney, fireplace or appliance Loose masonry on chimney Moisture inside of windows Notice problems that could indicate improper appliance operation: Decreasing hot water supply Furnace unable to heat house or runs constantly Sooting, especially on appliances Unfamiliar or burning odor A change in the gas flame's color. For example, if a blue flame becomes yellow, carbon monoxide will be increased; however, some blue flames produce elevated carbon monoxide levels as well, while some new appliances normally have a yellow flame. Health Problems Associated with Carbon Monoxide Carbon monoxide is absorbed through the lungs into the blood, where it interferes with the blood's ability to carry oxygen. That is because it binds with the red blood cells 210 times greater than oxygen. As a result, the tissues of the body do not get enough oxygen and die. There are many factors that determine if one might get sick from exposure to carbon monoxide. These include: The concentration and amount of carbon monoxide in the air. The average level of carbon monoxide in homes without gas stoves vary from 0.5 ppm to 5 ppm. Levels near properly adjusted gas stoves are often 5 ppm to 15 ppm and those near poorly adjusted stoves may be 30 ppm or higher. NIOSH recommends that airborne levels of carbon monoxide not exceed a 35 ppm average over a 10-hour period with a limit of 200 ppm not to be exceeded at any time in order to prevent health effects. The US Consumer Product Safety Commission (CSPC) says that the health effects of concentrations from 1 ppm to 70 ppm are uncertain but that most people will not experience any symptoms. Some heart patients, though, might experience an increase in chest pain. As carbon monoxide levels increase and remain above 70 ppm, symptoms may become more noticeable (headache, fatigue, nausea). As carbon monoxide levels increase above 150 ppm to 200 ppm, disorientation, unconsciousness, and death are possible.³ Personal characteristics such as age, gender, weight, general health status. Elderly, sick people, infants, and pets are first affected by carbon monoxide because they are less able to respond to adverse environments and they have smaller lung capacities. People with anemia or with a history of heart or respiratory disease can be especially sensitive to carbon monoxide exposures. Is a person exposed to just carbon monoxide or is it a variety of chemicals? How long is one exposed to carbon monoxide? The longer the exposure, the more at risk one is. Health problems caused by carbon monoxide can either be acute, which occur immediately or within a few days of exposure, or they can be chronic, which are the results of low-level of exposures over a long period. Some studies found that 25 percent to 40 percent of people died during acute exposure while 15 percent to 40 percent suffered immediate or delayed effects. New evidence is suggesting that longer exposures to lower levels of carbon monoxide is capable of producing many debilitating residual effects that may continue for days, weeks, months and even years.⁴ Many times carbon monoxide poisoning is not diagnosed since many of the symptoms are confused with the flu or food poisoning. In one study, nearly one-fourth of people complaining of flu were actually suffering from carbon monoxide poisoning. One of the main differences is that these symptoms usually improve when one leaves the area where the carbon monoxide is. The symptoms of carbon monoxide poisoning often affect everybody. Exposure to carbon monoxide can result in: Headaches Shortness of breath Muscle aches Chest pain (especially in people with pre-existing heart problems) Blurry vision Dizziness Nausea/vomiting Weakness Confusion Fatigue Rapid heart rate at high levels Fast, deep breathing at high levels At high levels, skin may turn a bright cherry-red color Fainting at high levels Death at high levels Though these are the typical symptoms associated with carbon monoxide poisoning, chronic carbon monoxide poisoning may not give these typical symptoms associated with acute exposure. As a result, chronic carbon monoxide poisoning is often misdiagnosed as chronic fatigue syndrome, an immune deficiency, or some viral or bacterial pulmonary or gastrointestinal infection. Chronic symptoms may also appear three weeks after exposure to dangerous levels of carbon monoxide. These may include: Personality changes Memory problems Parkinson's disease Visual loss Dementia The chronic effects were once blamed entirely on the hypoxia from the red blood cells not getting the oxygen it needed. However, researchers are now finding that carbon monoxide can travel in blood plasma and do cell damage without ever binding to the hemoglobin or showing up on a blood test. This "free" carbon monoxide in the bloodstream can trigger cell death of the lining of the heart and blood vessels, leading to atherosclerotic heart disease. The same process also appears to kill brain cells responsible for memory and learning.⁵ If you think you might be suffering from carbon monoxide poisoning, GET MEDICAL ATTENTION IMMEDIATELY. There is a simple blood test that can determine if carbon monoxide is the problem (it measures carboxyhemoglobin in the blood and is relatively inexpensive depending on where a person lives.) Lower levels of carbon monoxide poisoning can be treated with supplemental oxygen. Nevertheless, at higher levels, hyperbaric oxygen treatments may be needed. This increases the amount of oxygen dissolved in the blood and forces the carbon monoxide off the red blood cells so it can carry oxygen again. What To Do in Case of CO Exposure Get fresh air immediately. Open doors and windows, turn off combustion appliances, and leave the building. Call your fire department and report your symptoms. Most fire departments have special meters that can measure the level of carbon monoxide. If you go to a hospital, tell the physician you suspect carbon monoxide poisoning. If that is the problem, it can be diagnosed by a blood test if done immediately after exposure. Be prepared to answer the following questions for the doctor: Do your symptoms occur only in the house or building? Do they disappear or decrease when you leave home and reappear when you return? Is anyone else in your household complaining of similar symptoms? Did everyone's symptoms appear about the same time? Are you using any fuel-burning appliances in the home? Has anyone inspected your appliances lately? Are you certain they are working properly? *Do not ignore symptoms, particularly if more than one person is feeling them. You could lose consciousness and die, if you do nothing. Decreasing Exposure to Carbon Monoxide* To minimize exposure to carbon monoxide: Install a carbon monoxide alarm in your home. Carbon monoxide alarms are widely available in stores and you may want to consider buying one as a backup BUT NOT AS A REPLACEMENT for proper use and maintenance of your fuel-burning appliances. For maximum effectiveness during sleeping hours, carbon monoxide alarms should be placed as close to sleeping areas as possible. Only buy combustion appliances that have been tested and certified to meet current safety standards. Examples of certifying organizations are Underwriters Laboratories (UL) and the American Gas Association (AGA) Laboratories. Look for a label that clearly shows the certification. Choose "sealed combustion" or "direct vent" gas appliances, with their exhaust vents and air supplies completely sealed from the indoors, to keep combustion products from entering the home. You may want to consider using other alternatives such as new, high-efficiency electric appliances or solar heating systems. Before considering using an unvented space heater, check with your local and state building codes and fire ordinances. These types of unvented heaters are not allowed to be used in some communities, dwellings, or certain rooms in the house. Have a trained professional inspect your fuel-burning appliances?including oil and gas furnaces, gas water heaters, gas ranges and ovens, gas dryers, gas or kerosene space heaters, fireplaces, and wood stoves at the beginning of every heating season. The central heating system (furnaces, flues and chimneys) should also be inspected, cleaned and tuned-up annually. Install combustion appliances away from the home's living area (such as living room and bedrooms). Read and follow all of the instructions that accompany any fuel-burning device. If you cannot avoid using an unvented gas or kerosene space heater, carefully follow the cautions that come with the device. Use the proper fuel and keep doors to the rest of the house open. Also, make sure any space heater you use is a new one. Heaters made after 1982 have a pilot light safety system called an oxygen depletion sensor (ODS). This system shuts off the heater when there is not enough fresh air and the heater is beginning to produce large amounts of carbon monoxide. Look for the label that tells you that the appliance has this safety system. Older heaters will not have this protection system. Never idle the car in a garage even if the garage door to the outside is open. Exhaust vapors can build up very quickly in the garage and living area of your home. If you are in heavy traffic, keep your windows rolled up. This is especially true if you are caught in traffic in an enclosed space like a tunnel. *NEVER* use a gas oven to heat your home even for a short time. According to the Centers for Disease Control and Prevention (CDC), between 1988 and 1994 almost 7.7 million people used their gas stove or oven for heat at least once during the previous year. This dangerous practice was most common among rural, low-income, and African-American households.⁶ Do not ever use a charcoal grill or hibachi indoors even in a fireplace or garage. This also applies to tents and camping trailers. According to the CPSC, about 30 people die every year and 450 are treated at hospitals, for carbon monoxide poisoning from using portable camping equipment inside tents, campers and vehicles. In addition, 25 people die annually from burning charcoal in enclosed areas. Often this is an attempt by campers or hunters to keep warm. If you are camping, keep the charcoal grill outside and turn off the portable lanterns and heaters when you go to sleep. Never sleep in any room with an unvented gas or kerosene space heater. Do not use any gasoline-powered engines (mowers, weed trimmers, snow blowers, chain saws, small engines or generators) in enclosed spaces. Use pilotless (electronic) ignition on gas appliances. These appliances are usually more energy efficient and eliminate the continuous low-level pollutants from pilot lights. Choose appliances, such as gas dryers, that vent their fumes to the outside. Have them properly installed and maintain according to the manufacturer's instructions. Never disconnect vents on combustion appliances, even if it seems like a way to get extra heat in the winter. Supply adequate outdoor make-up air for combustion so there will not be backdrafting into the indoor environment. Inspect and clean flues and chimneys regularly to make sure they are in good condition and not blocked. Appliances designated as supplemental or "decorative" heaters (including most unvented gas fireplaces) are not designed for continuous use. To avoid excessive exposure to pollutants, never use these appliances for more than four hours at a time. When operating unvented combustion appliances, safe practices must be carefully followed. Besides observing fire safety rules, make sure the burner is properly adjusted and there is good ventilation never use in a closed room, keep doors open throughout the house, and open a window for fresh air. Use proper fuel in kerosene space heaters. Only use water-clear ASTM 1-K kerosene for kerosene heaters, otherwise you could have even more pollutants get in your home. Never use gasoline in a kerosene heater because it can cause a fire or an explosion. Using even small amounts of gasoline could cause a fire. Install and use an exhaust fan vented to outdoors over gas stoves. Remove and clean the metal mesh filters on your range hoods with detergent when they begin to look grimy (most can be put in the dishwasher). "Ductless" range hoods are not effective because they exhaust into the house rather than outside; add a duct or replace the hood with one vented to the outside (ducted). Open flues when fireplaces are in use. Choose properly sized wood stoves that are certified to meet EPA emission standards. Make certain that doors on all wood stoves fit tightly. Use only seasoned hardwoods (elm, maple, oak) instead of softwoods (cedar, fir, pine) in fireplaces or stoves. Hardwoods are better because they burn hotter and form less creosote, an oily, black tar that sticks to chimneys and stovepipes. Do not use green or wet woods as the primary wood because they make more creosote and smoke. Never burn painted scrap wood or wood treated with preservatives, because they could release highly toxic pollutants, such as arsenic or lead. Plastics, charcoal, and colored paper such as comics, also produce pollutants. Never burn anything that the stove or fireplace manufacturer does not recommend. Do not allow the use of or operate gasoline-powered engines or tools inside buildings or in partially enclosed areas unless gasoline engines can be located outside and away from air intakes. Use of gasoline-powered tools indoors where carbon monoxide from the engine can accumulate can be fatal. Learn to recognize the symptoms and signs of overexposure to carbon monoxide: headache, nausea, weakness, dizziness, visual disturbances, changes in personality and loss of consciousness. Any of these symptoms and signs can occur within minutes of usage. If you or another person(s) exhibits any of these symptoms, *GET MEDICAL ATTENTION IMMEDIATELY. Always place the pump and power unit of high-pressure washers outdoors and away from air intakes so that engine exhaust is not drawn indoors where the work is being done. Run only the high-pressure wash line inside. Consider the use of tools powered by electricity or compressed air if they are available and can be used safely. For example, electric-powered tools present an electrocution hazard and require specific precautions for safety. Use electric-powered forklifts if they are available instead of gas-powered ones. If compressed air is used, place the gasoline-powered compressor outdoors and away from air intakes so that engine exhaust is not drawn indoors where the work is being done. References* "Experts weigh in on carbon-monoxide detectors," The Seattle Times. August 2, 2000:E8. Earnest G, Mickelsen RL, McCammon JB, O'Brien DM. Carbon monoxide poisonings from small, gasoline-powered, internal combustion engines: Just what is a "well-ventilated area?" American Industrial Hygiene Association Journal. 1997;58:787-791. Consumer Product Safety Commission. Carbon Monoxide Questions and Answers. CPSC Document #466. Penney D. Carbon Monoxide Headquarters. Wayne State University School of Medicine. [www.phymac.med.wayne.edu/FacultyProfile/penney/COHQ/co1.htm] Date accessed: August 2000. Roylance FD. Unsafe at any amount: Low levels of carbon monoxide seeping from a furnace create bigger health problems than most people suspect. The Seattle Times. July 19, 2000. Use of Unvented Residential Heating Appliances?United States, 1988-1994, MMWR. December 26, 1997;46(51):1221-1224.