This document may be reproduced without change,
in whole or in part, without permission, except for use as advertising material
or product endorsement. Any such reproduction should credit the American Lung
Association, the U.S. Consumer Product Safety Commission, and the U.S. Environmental
Protection Agency. The use of all or any part of this document in a deceptive
manner or for purposes of endorsing a particular product may be subject to appropriate
Note: The CPSC and the EPA have not reviewed or approved all the information and
documents on indoor air quality that may be provided by other groups or organizations.
Hazards may be associated with almost all types
of appliances. The purpose of this document is to answer some common questions
you may have about the potential for one specific type of hazard - indoor air
pollution - associated with one class of appliances - combustion appliances.
Combustion appliances are those which burn
fuels for warmth, cooking, or decorative purposes. Typical fuels are gas, both
natural and liquefied petroleum (LP); kerosene; oil; coal; and wood. Examples
of the appliances are space heaters, ranges, ovens, stoves, furnaces, fireplaces,
water heaters, and clothes dryers. These appliances are usually safe. However,
under certain conditions, these appliances can produce combustion pollutants
that can damage your health, or even kill you.
Possible Health Effects
Similar effects may also occur because of common
medical problems or other indoor air pollutants.
YES. Studies have shown that the air in our homes can be even more polluted than
the outdoor air in big cities. Because people spend a lot of time indoors, the
quality of the air indoors can affect their health. Infants, young children
and the elderly are a group shown to be more susceptible to pollutants. People
with chronic respiratory or cardiovascular illness or immune system diseases
are also more susceptible than others to pollutants.
Many factors determine whether pollutants in
your home will affect your health. They include the presence, use, and condition
of pollutant sources, the level of pollutants both indoors and out, the amount
of ventilation in your home, and your overall health.
Most homes have more than one source of indoor
air pollution. For example, pollutants come from tobacco smoke, building materials,
decorating products, home furnishings, and activities such as cooking, heating,
cooling, and cleaning. Living in areas with high outdoor levels of pollutants
usually results in high indoor levels. Combustion pollutants are one category
of indoor air pollutants.
Combustion pollutants are gases or particles
that come from burning materials. The combustion pollutants discussed in this
document come from burning fuels in appliances. The common fuels burned in these
appliances are natural or LP gas, fuel oil, kerosene, wood, or coal. The types
and amounts of pollutants produced depend upon the type of appliance, how well
the appliance is installed, maintained, and vented, and the kind of fuel it
uses. Some of the common pollutants produced from burning these fuels are carbon
monoxide, nitrogen dioxide, particles, and sulfur dioxide. Particles can have
hazardous chemicals attached to them. Other pollutants that can be produced
by some appliances are unburned hydrocarbons and aldehydes.
Combustion always produces water vapor. Water
vapor is not usually considered a pollutant, but it can act as one. It can result
in high humidity and wet surfaces. These conditions encourage the growth of
biological pollutants such as house dust mites, molds, and bacteria.
Combustion pollutants found indoors include:
outdoor air, tobacco smoke, exhaust from car and lawn mower internal combustion
engines, and some hobby activities such as welding, woodburning, and soldering.
Combustion pollutants can also come from vented or unvented combustion appliances.
These appliances include space heaters, gas ranges and ovens, furnaces, gas
water heaters, gas clothes dryers, wood or coal-burning stoves, and fireplaces.
As a group these are called "combustion appliances."
The health effects of combustion pollutants
range from headaches and breathing difficulties to death. The health effects
may show up immediately after exposure or occur after being exposed to the pollutants
for a long time. The effects depend upon the type and amount of pollutants and
the length of time of exposure to them. They also depend upon several factors
related to the exposed person. These include the age and any existing health
problems. There are still some questions about the level of pollutants or the
period of exposure needed to produce specific health effects. Further studies
to better define the release of pollutants from combustion appliances and their
health effects are needed.
The sections below discuss health problems
associated with some common combustion pollutants. These pollutants include
carbon monoxide, nitrogen dioxide, particles, and sulfur dioxide. Even if you
are healthy, high levels of carbon monoxide can kill you within a short time.
The health effects of the other pollutants are generally more subtle and are
more likely to affect susceptible people. It is always a good idea to reduce
exposure to combustion pollutants by using and maintaining combustion appliances
Each year, according to CPSC, there are more
than 200 carbon monoxide deaths related to the use of all types of combustion
appliances in the home. Exposure to carbon monoxide reduces the blood's ability
to carry oxygen. Often a person or an entire family may not recognize that carbon
monoxide is poisoning them. The chemical is odorless and some of the symptoms
are similar to common illnesses. This is particularly dangerous because carbon
monoxide's deadly effects will not be recognized until it is too late to take
action against them.
Carbon monoxide exposures especially affect
unborn babies, infants, and people with anemia or a history of heart disease.
Breathing low levels of the chemical can cause fatigue and increase chest pain
in people with chronic heart disease. Breathing higher levels of carbon monoxide
causes symptoms such as headaches, dizziness, and weakness in healthy people.
Carbon monoxide also causes sleepiness, nausea, vomiting, confusion, and disorientation.
At very high levels it causes loss of consciousness and death.
Breathing high levels of nitrogen dioxide causes
irritation of the respiratory tract and causes shortness of breath. Compared
to healthy people, children, and individuals with respiratory illnesses such
as asthma, may be more susceptible to the effects of nitrogen dioxide.
Some studies have shown that children may have
more colds and flu when exposed to low levels of nitrogen dioxide. When people
with asthma inhale low levels of nitrogen dioxide while exercising, their lung
airways can narrow and react more to inhaled materials.
Particles suspended in the air can cause eye,
nose, throat, and lung irritation. They can increase respiratory symptoms, especially
in people with chronic lung disease or heart problems. Certain chemicals attached
to particles may cause lung cancer, if they are inhaled. The risk of lung cancer
increases with the amount and length of exposure. The health effects from inhaling
particles depend upon many factors, including the size of the particle and its
Sulfur dioxide at low levels of exposure can
cause eye, nose, and respiratory tract irritation. At high exposure levels,
it causes the lung airways to narrow. This causes wheezing, chest tightness,
or breathing problems. People with asthma are particularly susceptible to the
effects of sulfur dioxide. They may have symptoms at levels that are much lower
than the rest of the population.
If you suspect you are being subjected to carbon monoxide poisoning get fresh
air immediately. Open windows and doors for more ventilation, turn off any combustion
appliances, and leave the house. You could lose consciousness and die from carbon
monoxide poisoning if you do nothing. It is also important to contact a doctor
IMMEDIATELY for a proper diagnosis. Remember to tell your doctor that
you suspect carbon monoxide poisoning is causing your problems. Prompt medical
attention is important.
Remember that some symptoms from combustion pollutants - headaches, dizziness,
sleepiness, coughing, and watery eyes - may also occur because of common medical
problems. These medical problems include colds, the flu, or allergies. Similar
symptoms may also occur because of other indoor air pollutants. Contact your
doctor for a proper diagnosis.
To help your doctor make the correct diagnosis, try to have answers to the following
Do your symptoms occur only in the home? Do they disappear or decrease
when you leave home, and reappear when you return?
Is anyone else in your household complaining of similar symptoms, such
as headaches, dizziness, or sleepiness? Are they complaining of nausea, watery
eyes, coughing, or nose and throat irritation?
Do you always have symptoms?
Are your symptoms getting worse?
Do you often catch colds or get the flu?
Are you using any combustion appliances in your home?
Has anyone inspected your appliances lately? Are you certain they are working
Your doctor may take a blood sample to measure
the level of carbon monoxide in your blood if he or she suspects carbon monoxide
poisoning. This sample will help determine whether carbon monoxide is affecting
Contact qualified appliance service people
to have your appliances inspected and adjusted if needed. You should be able
to find a qualified person by asking your appliance distributor or your fuel
supplier. In some areas, the local fuel company may be able to inspect and adjust
Proper selection, installation, inspection
and maintenance of your appliances are extremely important in reducing your
exposure to these pollutants. Providing good ventilation in your home and correctly
using your appliance can also reduce your exposure to these pollutants.
Additionally, there are several different residential
carbon monoxide detectors for sale. The CPSC is encouraging the development
of detectors that will provide maximum protection. These detectors would warn
consumers of harmful carbon monoxide levels in the home. They may soon be widely
available to reduce deaths from carbon monoxide poisoning.
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.
All currently manufactured vented gas heaters are required by industry
safety standards to have a safety shut-off device. This device helps protect
you from carbon monoxide poisoning by shutting off an improperly vented heater.
Check your local and state building codes and fire ordinances to see if
you can use an unvented space heater, if you consider purchasing one. They
are not allowed to be used in some communities, dwellings, or certain rooms
in the house.
If you must replace an unvented gas space heater with another, make it
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, before the heater begins producing 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.
Consider buying gas appliances that have electronic ignitions rather than
pilot lights. These appliances are usually more energy efficient and eliminate
the continuous low-level pollutants from pilot lights.
Buy appliances that are the correct size for the area you want to heat.
Using the wrong size heater may produce more pollutants in your home and is
not an efficient use of energy.
Talk to your dealer to determine the type and size of appliance you will
need. You may wish to write to the appliance manufacturer or association for
more information on the appliance. Some addresses are in the back of this
All new woodstoves are EPA-certified to limit the amounts of pollutants
released into the outdoor air. For more information on selecting, installing,
operating, and maintaining woodburning stoves, write to the EPA Wood Heater
Program. Their address is at the bottom of this document. Before buying a
woodstove check your local laws about the installation and use of woodstoves.
You should have your appliances professionally
installed. Professionals should follow the installation directions and applicable
building codes. Improperly installed appliances can release dangerous pollutants
in your home and may create a fire hazard. Be sure that the installer checks
for backdrafting on all vented appliances. A qualified installer knows how to
To reduce indoor air pollution, a good supply of fresh outdoor air is needed.
The movement of air into and out of your home is very important. Normally,
air comes through cracks around doors and windows. This air helps reduce the
level of pollutants indoors. This supply of fresh air is also important to
help carry pollutants up the chimney, stovepipe, or flue to the outside.
Keep doors open to the rest of the house from the room where you are using
an unvented gas space heater or kerosene heater, and crack open a window.
This allows enough air for proper combustion and reduces the level of pollutants,
especially carbon monoxide.
Use a hood fan, if you are using a range. They reduce the level of pollutants
you breath, if they exhaust to the outside. Make sure that enough air is coming
into the house when you use an exhaust fan. If needed, slightly open a door
or window, especially if other appliances are in use. For proper operation
of most combustion appliances and their venting system, the air pressure in
the house should be greater than that outside. If not, the vented appliances
could release combustion pollutants into the house rather than outdoors. If
you suspect that you have this problem you may need the help of a qualified
person to solve it.
Make sure that your vented appliance has the vent connected and that nothing
is blocking it. Make sure there are no holes or cracks in the vent. Do not
vent gas clothes dryers or water heaters into the house for heating. This
Open the stove's damper when adding wood. This allows more air into the
stove. More air helps the wood burn properly and prevents pollutants from
being drawn back into the house instead of going up the chimney. Visible smoke
or a constant smoky odor inside the home when using a woodburning stove is
a sign that the stove is not working properly. Soot on furniture in the rooms
where you are using the stove also tells this. Smoke and soot are signs that
the stove is releasing pollutants into the indoor air.
Read and follow the instructions for all appliances so you understand how
they work. Keep the owner's manual in a convenient place to refer to when
needed. Also, read and follow the warning labels because they tell you important
safety information that you need to know. Reading and following the instructions
and warning labels could save your life.
Always use the correct fuel for the appliance.
Only use water-clear ASTM 1-K kerosene for kerosene heaters. The use of
kerosene other than 1-K could lead to a release of more pollutants 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.
Use seasoned hardwoods (elm, maple, oak) instead of softwoods (cedar, fir,
pine) in woodburning stoves and fireplaces. Hardwoods are better because they
burn hotter and form less creosote, an oily, black tar that sticks to chimneys
and stove pipes. 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.
Never use a range, oven, or dryer to heat your home. When you misuse gas
appliances in this way, they can produce fatal amounts of carbon monoxide.
They can produce high levels of nitrogen dioxide, too.
Never use an unvented combustion heater overnight or in a room where you
are sleeping. Carbon monoxide from combustion heaters can reach dangerous
Never ignore a safety device when it shuts off an appliance. It means that
something is wrong. Read your appliance instructions to find out what you
should do or have a professional check out the problem.
Never ignore the smell of fuel. This usually indicates that the appliance
is not operating properly or is leaking fuel. Leaking fuel will not always
be defectible by smell. If you suspect that you have a fuel leak have it fixed
as soon as possible. In most cases you should shut off the appliance, extinguish
any other flames or pilot lights, shut off other appliances in the area, open
windows and doors, call for help, and leave the area.
Inspection and Maintenance
Have your combustion appliance regularly inspected and maintained to reduce
your exposure to pollutants. Appliances that are not working properly can
release harmful and even fatal amounts of pollutants, especially carbon monoxide.
Have chimneys and vents inspected when installing or changing vented heating
appliances. Some modifications may be required. For example, if a change was
made in your heating system from oil to natural gas, the flue gas produced
by the gas system could be hot enough to melt accumulated oil combustion debris
in the chimney or vent. This debris could block the vent forcing pollutants
into the house. It is important to clean your chimney and vents especially
when changing heating systems.
What are the inspection and maintenance procedures?
The best advice is to follow the recommendations of the manufacturer. The same
combustion appliance may have different inspection and maintenance requirements,
depending upon where you live.
In general, check the flame in the furnace
the combustion chamber at the beginning of the heating season. Natural gas furnaces
should have a blue flame with perhaps only a slight yellow tip. Call your appliance
service representative to adjust the burner if there is a lot of yellow in the
flame, or call your local utility company for this service. LP units should
have a flame with a bright blue center that may have a light yellow tip. Pilot
lights on gas water heaters and gas cooking appliances should also have a blue
flame. Have a trained service representative adjust the pilot light if it is
yellow or orange.
Before each heating season, have flues and
chimneys inspected and cleaned before each heating season for leakage and for
blockage by creosote or debris. Creosote buildup or leakage could cause black
stains on the outside of the chimney or flue. These stains can mean that pollutants
are leaking into the house.
The chart below shows how and when to take
care of your appliance.
This document discussed the types of pollutants
that may be produced by combustion appliances, described how they might affect
your health, and suggested ways you could reduce your exposure to them. It also
explained that proper appliance selection, installation, operation, inspection,
and maintenance are very important in reducing exposure to combustion pollutants.
Wood Heater Program
U.S. Environmental Protection Agency
Manufacturing, Energy, and Transportation Division (2223A)
401 M Street, SW
Washington, DC 20460
(202) 564-2300/(202) 564-0050 (fax)
For information on kerosene heaters, write or call:
National Kerosene Heater Association
3100 West End Avenue, Suite 250
Nashville, TN 37203
For information on gas heating appliances, write:
Gas Appliance Manufacturers Association, Inc.
1901 North Moore Street, Suite 1100
Arlington, VA 22209
American Gas Association
1515 Wilson Blvd.
Arlington, VA 22209
For a copy of Straight Answers to Burning Questions
or other wood burning information, write:
Wood Heating Alliance
1101 Connecticut Ave NW, Suite 700
Washington, DC 20036