Chemicals That Go Up in Smoke:
The Hazards of Gas Stoves, Fireplaces, Kerosene Heaters,
and Cigarette Smoke
The burning, or combustion, of wood or fuels like natural gas or kerosene can be a formidable source of pollution, particularly if your home is poorly ventilated. Smoke, whether from a fireplace, cigarette, car emissions, or incense, contains thousands of chemicals, including cancer-causing substances and allergens. We now know that secondhand smoke can cause lung cancer, heart disease, asthma, and respiratory infections. Infants are even more vulnerable than adults. Exposure to tobacco smoke has doubled the incidence of pneumonia, bronchitis, and other respiratory ailments among infants and children up to age three. Similarly, exposure to pollutants from combustion appliances, heaters, and fireplaces also increases the risk of cancer, respiratory infections, heart disease, and retarded fetal development. Children living in homes heated with wood are more likely to develop respiratory illnesses. In the United States, 37 percent of all deaths in the first year of life are the result of lung disease and breathing problems, which are the leading cause of disease and death among newborns, according to the American Lung Association. Wood smoke has become a significant part of outdoor air pollution, too. In Washington state, for example, residential wood stoves and fireplaces release 10 percent of the state's total air pollution.
Because many of the particles and gasses found in smoke and fuel emissions are undetectable to us, we often don't realize the dangers that we may be exposing ourselves and our loved ones to. Some of the gas and particle byproducts of combustion include:
- Carbon monoxide (CO). A colorless and odorless gas, carbon monoxide is absorbed easily into the bloodstream and starves it of oxygen. Automobile exhaust is one of the main sources, but other combustibles also produce CO. At low levels, this gas causes fatigue in healthy people and chest pain in those with heart disease. Symptoms of exposure to moderate to high levels include impaired vision and coordination, headaches, dizziness, nausea, vomiting, memory loss, and flulike symptoms. At high doses, CO is fatal. Nearly 300 people die each year from CO poisoning in their homes, according to the Consumer Product Safety Commission (CPSC). Another 5,000 are treated in emergency rooms after exposure, but this is believed to be an underestimation, because many confuse the symptoms with those of the flu.
- Nitrogen dioxide (NO2). A sharp-smelling, colorless gas, nitrogen dioxide irritates eyes, nose, throat, and lungs and can cause coughing, headaches, and nausea. In homes with gas stoves, kerosene heaters, and unvented gas space heaters, NO2 levels often exceed outdoor levels, according to the EPA. Short-term exposures can increase the risk of respiratory infection, especially in young children, and trigger asthma attacks. Long-term exposure may result in permanent damage to lung tissue.
- Sulfur dioxide (SO2). This gas is produced by sulfur-containing fuels such as kerosene space heaters and wood-burning stoves and can aggravate symptoms of asthma and bronchitis.
- Small inhalable particles, or particulates. Particles produced by combustion are often small enough to penetrate deep into the lungs. "Particulates can remain suspended for up to three weeks and can travel up to 700 miles," says Jamie Craighill, wood smoke coordinator for the Washington State Department of Ecology's Air Quality Program. These particles may also attach to other toxic substances and carry them into the lungs and mucous membranes. Long-term exposure may lead to lung cancer, asthma, and bronchitis. When walking or running, we kick up these particles, making it more likely that we'll breathe them in. Children risk even greater exposure to these particles. Crawling on the ground, they may ingest five times more dust than an adult, as much as 100 milligrams per day, report John Roberts and Wayne Ott in the February 1998 issue of Scientific American.
- Polycyclic aromatic hydrocarbons (PAHs). These can be found in either gas or particle form in the home. Tarlike PAHs are found in smoke, soot, ash, and creosote from wood, coal, and tobacco. Some PAH compounds have been linked to cancers of the lung, stomach, skin, and bladder in humans. They may also impact reproductive systems. Every day, the average urban infant will ingest 110 nanograms of benzo-a-pyrene, the most toxic polycyclic aromatic hydrocarbon, according to Ott and Roberts. A child would take in the same amount of this PAH by smoking three cigarettes.
Particles and PAHs produced from combustion cling to soil and dust, which may be tracked around the house on shoes and infiltrate rooms through open windows and ducts. These pollutants can be inhaled, absorbed through the skin, and ingested from hand-to-mouth contact.
Sources of Combustion Pollutants
There are three primary sources of combustion pollutants in the home. Unvented appliances, such as gas stoves and kerosene heaters, can be worrisome because they do not have an exhaust fan or flue that carries pollutants out of and away from the house. Even unvented pilot lights in gas appliances can increase indoor air pollution, according to the EPA. It's best to vent appliances to the outdoors whenever possible. And kitchen windows must be easily opened so that gases and particles can be dispersed.
Vented appliances, including most furnaces, wood stoves, fireplaces, gas water heaters, and gas clothes dryers, are supposed to exhaust pollutants outdoors through vents, flues, or ducts. But exhaust leakage, due to cracked heat exchangers or blocked vents, may cause the pollutants to seep into the home instead. Blocked flues or chimneys can cause backdrafts, or a reversal of airflow through a chimney or flue. Backdrafts push smoke into the house instead of outward. They are also caused by lowered air pressure, or depressurization, which occurs when other chimneys, exhaust fans, or forced air systems pull air from the house without adequate air replacement, producing a "suction" effect. "Even operating a clothes dryer, which expels air outdoors through a vent, can cause a backdraft, particularly when the fire is low," says Jamie Craighill.
Secondhand smoke, or the smoke from smoldering tobacco, emits more than 4,000 particles and gasses. At least forty of these, such as formaldehyde and benzene, are carcinogenic. Infants of smokers have a higher incidence of ear infections and may suffer reduced lung function and lung growth. Maternal smoking impacts fetal development as well and increases the risk of Sudden Infant Death Syndrome (SIDS).
Other activities related to combustion may also degrade indoor air quality. Pollutants from an idling car or fuel-burning heaters in the garage may seep into the house. Grilling or burning food, the oven-cleaning cycle on your kitchen stove, welding and soldering projects, and incense and candles release particles and gasses into the air as well.
Polluted outdoor air from passing traffic, outdoor barbecues, wood stoves and fireplaces in neighboring homes, and gas-powered lawnmowers can enter your home through open doors and windows.
Reducing Combustion Pollutants in Your Home
Once combustion pollutants contaminate your home, they are very difficult to remove. Particles cling to carpets, furniture, curtains, and household dust, and gasses spread throughout the house. You need not replace all your gas appliances and board up your fireplace. Instead, reduce contamination as much as possible by doing the following:
- Install carbon monoxide alarms, which cost between $50 and $80, in hallways outside bedrooms and the nursery. CO disperses fairly quickly and evenly throughout the house, so you won't need alarms next to every gas appliance, which might cause the alarm to react to short-lived, but high, amounts of CO. If you have a multilevel house, place one alarm near sleeping areas and others near, but not in, the kitchen and furnace room in the basement. Look for CO detectors that meet the Underwriters Laboratories standard 2034-this code is usually listed on the product and its packaging. Consumer Reports recommends plug-in detectors, such as those in the Nighthawk 900 series, American Sensors' CO920, and Lifesaver FYCO-6N, over battery-operated models. Don't rely on inexpensive plastic or cardboard detectors that indicate the presence of CO by changing color. Such devices will be useless when you are asleep.
- Make your home as smoke-free as possible. Keep as many smoking and burning activities as you can outdoors and away from open windows and doors.
- Make sure gas cooking stoves have adequate ventilation. Use a range hood with exhaust vents that direct smoke outside, or open windows for cross-ventilation each time you use the stove. Never use gas cooking stoves and ovens to heat your house.
- Avoid kerosene or gas-fired space heaters. If you need a space heater, use an electric or ceramic radiant heater. Both may outgas when first operated, but you can dissipate harmful fumes by operating the new heater on "high" in a ventilated garage or outdoors under close supervision. If you must resort to fuel-powered space heaters, use them only during emergencies for short periods of time in well-ventilated rooms (open a window slightly). Try to avoid using fuel-powered space heaters in small rooms. Follow manufacturer's directions faithfully, and never leave a space heater unattended.
- Never use charcoal grills, hibachis, or portable camping stoves indoors, in garages and sheds, on balconies, in tents, or near open windows. About twenty-five people die and several hundred become ill each year from use of charcoal indoors, according to CPSC.
- Decrease the operation time of unvented combustion heaters by weatherizing your home. Several books on energy efficiency explain how.
- Avoid operating motor vehicles, lawnmowers, or other combustion engines in an enclosed garage attached to your home or near open windows. Weatherstrip doors leading from the garage to the house to reduce the amount of car exhaust entering the house.
- Limit the use of woodburning stoves and fireplaces, particularly if your child has asthma or another chronic respiratory illness. Fireplaces are an inefficient and expensive way to heat your home, and they backdraft easily.
- If you do choose to use a fireplace or wood stove, clean and inspect the flue and chimney annually. A wood smoke or charred-wood smell at any time while a fire is burning usually means that something is obstructing the flue or chimney or there is a backdraft. Have it inspected before using it again! Wood stoves manufactured after 1992 are less polluting, using catalytic converters that burn fuel more completely, and require less wood to produce more heat. An EPA label on a wood stove certifies that it burns cleanly under laboratory conditions. Burn only dry, seasoned, and untreated wood for more efficient combustion and less pollution. Hardwoods, such as oak and maple, are better than soft pine and spruce. Never burn pressure-treated wood, particleboard, or plywood, which are filled with toxic chemicals. While it's okay to start a fire with newspaper, don't feed the fire with more newspaper, advises Jamie Craighill. "You don't know what kind of chemicals are in the ink," she says. Give the fire lots of air to make it burn as hot as possible. "The hotter the fire burns, the cleaner it burns," says Craighill.
- Have a trained professional inspect, clean, and tune gas appliances annually. She should examine heat exchangers, chimneys and flues, vents, ductwork, and filters for cracks and obstructions. Signs that you might have a leak or obstruction include:
- A constantly running furnace or one that cannot adequately heat the house
- Sooting, especially on appliances
- Decreasing hot water supply (if you have a gas water heater)
- A burning odor or other unusual smells
- Visible rust or stains on vents and chimneys
- Make sure your home is adequately ventilated. See "Good Ventilation" later in this chapter.
Excerpted from: Guideto Natural Baby Care, by Mindy Pennybackerand Aisha Ikramuddin
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