Outdoor air pollution in cities is a major health
problem. Much effort and money continues to be spent cleaning up
pollution in the outdoor air. But air pollution can be a problem
where you least expect it, in the place you may have thought was
safest - your home. Many ordinary activities such as cooking,
heating, cooling, cleaning, and redecorating can cause the
release and spread of indoor pollutants at home. Studies have
shown that the air in our homes can be even more polluted than
outdoor air. Many Americans spend up to 90 percent of their time
indoors, often at home. Therefore, breathing clean indoor air
can have an important impact on health. People who are inside a
great deal may be at greater risk of developing health problems,
or having problems made worse by indoor air pollutants. These
people include infants, young children the elderly and those
with chronic illnesses. 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.
What Are Biological Pollutants?
Biological pollutants are or were living
organisms. They promote poor indoor air quality and may be a
major cause of days lost from work or school, and of doctor and
hospital visits. Some can even damage surfaces inside and
outside your house. Biological pollutants can travel through the
air and are often invisible. Some common indoor biological
Animal Dander (minute scales from hair, feathers, or skin)
Dust Mite and Cockroach parts
Infectious agents (bacteria or viruses)
Some of these substances are in every home. It is
impossible to get rid of them all. Even a spotless home may
permit the growth of biological pollutants. Two conditions are
essential to support biological growth nutrients and moisture.
These conditions can be found in many locations, such as
bathrooms, damp or flooded basements, wet appliances (such as
humidifiers or air conditioners), and even some carpets and
furniture. Modern materials and construction techniques may
reduce the amount of outside air brought into buildings which
may result in high moisture levels inside. Using humidifiers,
un-vented heaters, and air conditioners in our homes has
increased the chances of moisture forming on interior surfaces.
This encourages the growth of certain biological pollutants.
The Scope Of The Problem
Most information about sources and health effects
of biological pollutants is based on studies of large office
buildings and surveys of homes in northern U.S. and Canada.
These surveys show that 30% to 50% of all structures have damp
conditions which may encourage the growth and buildup of
biological pollutants. This percentage is likely to be higher in
warm, moist climates. Some diseases or illnesses have been
linked with biological pollutants in the indoor environment.
However, many of them also have causes unrelated to the indoor
environment. Therefore, we do not know how many health problems
relate only to poor indoor air.
Health Effects Of Biological Pollutants
All of us are exposed to biological pollutants.
However, the effects on our health depend upon the type and
amount of biological pollution and the individual person. Some
people do not experience health reactions from certain
biological pollutants, while others may experience one or more
of the following reactions:
Except for the spread of infections indoors,
allergic reactions may be the most common health problem with
indoor air quality in homes. They are often connected with
animal dander (mostly from cats and dogs), with house dust mites
(microscopic animals living in household dust), and with pollen.
Allergic reactions can range from mildly uncomfortable to
life-threatening, as in a severe asthma attack. Some common
signs and symptoms are:
Runny nose and sneezing
Wheezing and difficulty breathing
Health experts are especially concerned about
people with asthma. These people have very sensitive airways
that can react to various irritants, making breathing difficult.
The number of people who have asthma has greatly increased in
recent years. The number of people with asthma has gone up by 59
percent since 1970, to a total of 9.6 million people. Asthma in
children under 15 years of age has increased 41 percent in the
same period, to a total of 2.6 million children. The number of
deaths from asthma is up by 68 percent since 1979, to a total of
almost 4,400 deaths per year.
Talking to Your Doctor
Are you concerned about the effects on your health that may be
related to biological pollutants in your home? Before you
discuss your concerns with your doctor, you should know the
answers to the following questions. This information can help
the doctor determine whether your health problems may be related
to biological pollution.
Does anyone in the family have frequent headaches, fevers,
itchy watery eyes, a stuffy nose, dry throat, or a cough?
Does anyone complain of feeling tired or dizzy all the time?
Is anyone wheezing or having difficulties breathing on a
Did these symptoms appear after you moved to a new or
Do the symptoms disappear when you go to school or the
office or go away on a trip, and return when you come back?
Have you recently remodeled your home or done any energy
conservation work, such as installing insulation, storm
windows, or weather stripping? Did your symptoms occur
during or after these activities?
Does your home feel humid? Can you see moisture on the
windows or on other surfaces, such as walls and ceilings?
What is the usual temperature in your home? Is it very hot
Have you recently had water damage?
Is your basement wet or damp?
Is there any obvious mold or mildew?
Does any part of your home have a musty or moldy odor?
Is the air stale?
Do you have pets?
Do your house plants show signs of mold?
Do you have air conditioners or humidifiers that have not
been properly cleaned?
Does your home have cockroaches or rodents?
Infectious diseases caused by bacteria and
viruses, such as flu, measles, chicken pox, and tuberculosis,
may be spread indoors. Most infectious diseases pass from person
to person through physical contact. Crowded conditions with poor
air circulation can promote this spread. Some bacteria and
viruses thrive in buildings and circulate through indoor
ventilation systems. For example, the bacterium causing
Legionnaire's disease, a serious and sometimes lethal infection,
and Pontiac Fever, a flu-like illness, have circulated in some
Toxic reactions are the least studied and
understood health problem caused by some biological air
pollutants in the home. Toxins can damage a variety of organs
and tissues in the body, including the liver, the central
nervous system, the digestive tract, and the immune system.
Checking Your Home
There is no simple and cheap way to sample the
air in your home to determine the level of all biological
pollutants. Experts suggest that sampling for biological
pollutants is not a useful problem-solving tool. Even if you had
your home tested, it is almost impossible to know which
biological pollutant(s) cause various symptoms or health
problems. The amount of most biological substances required to
cause disease is unknown and varies from one person to the next.
Does this make the problem sound hopeless? On the contrary, you
can take several simple, practical actions to help remove
sources of biological pollutants, to help get rid of pollutants,
and to prevent their return.
Self-Inspection: A Walk Through Your Home
Begin by touring your household. Follow your
nose, and use your eyes. Two major factors help create
conditions for biological pollutants to grow nutrients and
constant moisture with poor air circulation.
1. Dust and construction materials, such as wood, wallboard,
and insulation, contain nutrients that allow biological
pollutants to grow. Firewood also is a source of moisture,
fungi, and bugs.
2. Appliances such as humidifiers, kerosene and gas heaters,
and gas stoves add moisture to the air. A musty odor, moisture
on hard surfaces, or even water stains, may be caused by:
Basements, attics, and crawlspaces
Heating and air-conditioning ducts
Humidifiers and dehumidifiers
Refrigerator drip pans
What You Can Do About Biological Pollutants
Before you give away the family pet or move,
there are less drastic steps that can be taken to reduce
potential problems. Properly cleaning and maintaining your home
can help reduce the problem and may avoid interrupting your
normal routine. People who have health problems such as asthma,
or are allergic, may need to do this and more. Discuss this with
Water in your home can come from many sources.
Water can enter your home by leaking or by seeping through
basement floors. Showers or even cooking can add moisture to the
air in your home. The amount of moisture that the air in your
home can hold depends on the temperature of the air. As the
temperature goes down, the air is able to hold less moisture.
This is why, in cold weather, moisture condenses on cold
surfaces (for example, drops of water form on the inside of a
window). This moisture can encourage biological pollutants to
There are many ways to control moisture in your home:
Fix leaks and seepage. If water is entering the house from
the outside, your options range from simple landscaping to
extensive excavation and waterproofing. (The ground should
slope away from the house). Water in the basement can result
from the lack of gutters or a water flow toward the house.
Water leaks in pipes or around tubs and sinks can provide a
place for biological pollutants to grow.
Put a plastic cover over dirt crawlspaces to prevent
moisture from coming in from the ground. Be sure crawlspaces
Use exhaust fans in bathrooms and kitchens to remove
moisture to the outside (not into the attic). Vent your
clothes dryer to the outside.
Turn off certain appliances (such as humidifiers or kerosene
heaters) if you notice moisture on windows and other
Use dehumidifiers and air conditioners, especially in hot,
humid climates, to reduce moisture in the air, but be sure
that the appliances themselves don't become sources of
Raise the temperature of cold surfaces where
moisture condenses. Use insulation or storm windows. (A
storm window installed on the inside works better than one
installed on the outside) Open doors between rooms
(especially doors to closets which may be colder than the
rooms) to increase circulation. Circulation carries heat to
the cold surfaces Increase air circulation by using fans and
by moving furniture from wall corners to promote air and
heat circulation. Be sure that your house has a source of
fresh air and can expel excessive moisture from the home.
Pay special attention to carpet on concrete floors. Carpet
can absorb moisture and serve as a place for biological
pollutants to grow. Use area rugs which can be taken up and
washed often. In certain climates, if carpet is to be
installed over a concrete floor, it maybe necessary to use a
vapor barrier (plastic sheeting) over the concrete and cover
that with sub-flooring (insulation covered with plywood) to
prevent a moisture problem.
Moisture problems and their solutions differ
from one climate to another. The Northeast is cold and wet,
the Southwest is hot and dry, the South is hot and wet, and
the Western Mountain states are cold and dry. All of these
regions can have moisture problems. For example, evaporative
coolers used in the Southwest can encourage the growth of
biological pollutants. In other hot regions, the use of air
conditioners which cool the air too quickly may prevent the
air conditioners from running long enough to remove excess
moisture from the air. The types of construction and weather
for the different climates can lead to different problems
Where Biological Pollutants May Be Found in the Home
Dirty air conditioners
Dirty humidifiers and/or dehumidifiers
Bathroom without vents or windows
Kitchen without vents or windows
Dirty refrigerator drip pans
Laundry room with un-vented dryer
Carpet on damp basement floor
Closet on outside wall
Dirty heating/air conditioning system
Dogs or cats
Water damage (around windows, the roof or the
Maintain And Clean All Appliances That Come In Contact With
Have major appliances, such as furnaces, heat pumps and
central air conditioners, inspected and cleaned regularly by
a professional, especially before seasonal use. Change
filters on heating and cooling systems according to
manufacturer's directions. (In general, change filters
monthly during use.) When first turning on the heating or
air conditioning at the start of the season, consider
leaving your home until it airs out.
Have window or wall air-conditioning units cleaned and
serviced regularly by a professional, especially before the
cooling season. Air conditioners can help reduce the entry
of allergy-causing pollen. But they may also become a source
of biological pollutants if not properly maintained. Clean
the coils and rinse the drain pans according to
manufacturer's instructions, so water cannot collect in
Have furnace-attached humidifiers cleaned and serviced
regularly by a professional, especially before the heating
Follow manufacturer's instructions when using any type of
humidifier. Experts differ on the benefits of using
humidifiers. If you do use a portable humidifier
(approximately 1 to 2 gallon tanks), be sure to empty its
tank every day and refill with distilled or de-mineralized
water, or even fresh tap water if the other types of water
are unavailable For larger portable humidifiers, change the
water as recommended by the manufacturer. Unplug the
appliance before cleaning. Every third day, clean all
surfaces coming in contact with water with a 3% solution of
hydrogen peroxide, using a brush to loosen deposits Some
manufacturers recommend using diluted household bleach for
cleaning and maintenance, generally in a solution of
one-half cup bleach to one gallon water When any household
chemical, rinse well to remove all traces of chemical before
Empty dehumidifiers daily and clean often. If possible, have
the appliance drip directly into a drain. Follow
manufacturer's instructions for cleaning and maintenance.
Always disconnect the appliance before cleaning.
Clean refrigerator drip pans regularly
according to manufacturer's instructions. If refrigerator
and freezer doors don't seal properly, moisture may build up
and mold can grow. Remove any mold on door gaskets and
replace faulty gaskets.
Clean moist surfaces, such as showers and kitchen counters.
Remove mold from walls, ceilings, floors, and paneling. Do
not simply cover mold with paint, stain, varnish, or a
moisture-proof sealer, as it may resurface.
Replace moldy shower curtains, or remove them and scrub well
with a household cleaner and rinse before re-hanging them.
Controlling dust is very important for people who
are allergic to animal dander and mites. You cannot see mites,
but you can either remove their favorite breeding grounds or
keep these areas dry and clean. Dust mites can thrive in sofas,
stuffed chairs, carpets, and bedding. Open shelves, fabric
wallpaper, knickknacks, and blinds are also sources of dust
mites. Dust mites live deep in the carpet and are not removed by
vacuuming. Many doctors suggest that their mite-allergic
patients use washable area rugs rather than wall-to-wall carpet.
Always wash bedding in hot water (at least 130° F) to kill
dust mites. Cold water won't do the job. Launder bedding at
least every 7 to 10 days.
Use synthetic or foam rubber mattress pads and pillows, and
plastic mattress covers if you are allergic. Do not use
fuzzy wool blankets, feather or wool-stuffed comforters, and
Clean rooms and closets well, dust and vacuum
often to remove surface dust. Vacuuming and other cleaning
may not remove all animal dander, dust mite material, and
other biological pollutants. Some particles are so small
they can pass through vacuum bags and remain in the air. If
you are allergic to dust, wear a mask when vacuuming or
dusting. People who are highly allergy-prone should not
perform these tasks. They may even need to leave the house
when someone else is cleaning.
Before You Move
Protect yourself by inspecting your potential new home. If you
identify problems, have the landlord or seller correct them
before you move in, or even consider moving elsewhere.
Have professionals check the heating and cooling system,
including humidifiers and vents. Have duct lining and
insulation checked for growth.
Check for exhaust fans in bathrooms and kitchens. If there
are no vents, do the kitchen and bathrooms have at least one
window a piece? Does the cook top have a hood vented
outside? Does the clothes dryer vent outside? Are all vents
to the outside of the building, not in attics or
Look for obvious mold growth throughout the house, including
attics, basements, and crawlspaces and around the
foundation. See if there are many plants close to the house,
particularly if they are damp and rotting. They are a
potential source of biological pollutants. Downspouts from
roof gutters should route water away from the building.
Look for stains on the walls, floor or carpet
(including any carpet over concrete floors) as evidence of
previous flooding or moisture problems. Is there moisture on
windows and surfaces? Are there signs of leaks or seepage in
Look for rotted building materials which may suggest
moisture or water damage.
If you or anyone else in the family has a pet allergy, ask
if any pets have lived in the home.
Examine the design of the building. Remember that in cold
climates, overhanging areas, rooms over unheated garages,
and closets on outside walls may be prone to problems with
Look for signs of cockroaches. (Carefully read instructions
for use and any cautionary labeling on cleaning products
before beginning cleaning procedures.)
Do not mix any chemical products. Especially, never mix
cleaners containing bleach with any product (such as
ammonia) which does not have instructions for such mixing
When chemicals are combined, a dangerous gas can sometimes
Household chemicals may cause burning or irritation to skin
Household chemicals may be harmful if swallowed, or inhaled.
Avoid contact with skin, eyes, mucous membranes and
Avoid breathing vapor. Open all windows and doors and use an
exhaust fan that sends the air outside.
Keep household chemicals out of reach of children.
Rinse treated surface areas well to remove all traces of
Correcting Water Damage
What if damage is already done? Follow these guidelines for
correcting water damage:
Throw out mattresses, wicker furniture, straw baskets and
the like that have been water damaged or contain mold. These
cannot be recovered.
Discard any water-damaged furnishings such as carpets,
drapes, stuffed toys, upholstered furniture and ceiling
tales, unless they can be recovered by steam cleaning or hot
water washing and thorough drying.
Remove and replace wet insulation to prevent
conditions where biological pollutants can grow.
Reducing Exposure to Biological Contaminants
General good housekeeping, and maintenance of
heating and air conditioning equipment, are very important.
Adequate ventilation and good air distribution also help. The
key to mold control is moisture control. If mold is a problem,
clean up the mold and get rid of excess water or moisture.
Maintaining the relative humidity between 30% - 60% will help
control mold, dust mites, and cockroaches. Employ integrated
pest management to control insect and animal allergens. Cooling
tower treatment procedures exist to reduce levels of Legionella
and other organisms.
Install and use exhaust fans that are vented to the outdoors in
kitchens and bathrooms and vent clothes dryers outdoors. These
actions can eliminate much of the moisture that builds up from
everyday activities. There are exhaust fans on the market that
produce little noise, an important consideration for some
people. Another benefit to using kitchen and bathroom exhaust
fans is that they can reduce levels of organic pollutants that
vaporize from hot water used in showers and dishwashers.
Ventilate the attic and crawl spaces to prevent moisture
build-up. Keeping humidity levels in these areas below 50
percent can prevent water condensation on building materials.
If using cool mist or ultrasonic humidifiers,
clean appliances according to manufacturer's instructions and
refill with fresh water daily. Because these humidifiers can
become breeding grounds for biological contaminants, they have
the potential for causing diseases such as hypersensitivity
pneumonitis and humidifier fever. Evaporation trays in air
conditioners, dehumidifiers, and refrigerators should also be
Thoroughly clean and dry water-damaged carpets and building
materials (within 24 hours if possible) or consider removal and
replacement. Water-damaged carpets and building materials can
harbor mold and bacteria. It is very difficult to completely rid
such materials of biological contaminants.
Keep the house clean. House dust mites, pollens,
animal dander, and other allergy-causing agents can be reduced,
although not eliminated, through regular cleaning. People who
are allergic to these pollutants should use allergen-proof
mattress encasements, wash bedding in hot (130Â° F) water, and
avoid room furnishings that accumulate dust, especially if they
cannot be washed in hot water. Allergic individuals should also
leave the house while it is being vacuumed because vacuuming can
actually increase airborne levels of mite allergens and other
biological contaminants. Using central vacuum systems that are
vented to the outdoors or vacuums with high efficiency filters
may also be of help.
Take steps to minimize biological pollutants in
basements. Clean and disinfect the basement floor drain
regularly. Do not finish a basement below ground level unless
all water leaks are patched and outdoor ventilation and adequate
heat to prevent condensation are provided. Operate a
dehumidifier in the basement if needed to keep relative humidity
levels between 30 - 50 percent.
Health Effects From Biological Contaminants
Some biological contaminants trigger allergic reactions,
including hypersensitivity pneumonitis, allergic rhinitis, and
some types of asthma. Infectious illnesses, such as influenza,
measles, and chicken pox are transmitted through the air. Molds
and mildews release disease-causing toxins. Symptoms of health
problems caused by biological pollutants include sneezing,
watery eyes, coughing, shortness of breath, dizziness, lethargy,
fever, and digestive problems.
Allergic reactions occur only after repeated
exposure to a specific biological allergen. However, that
reaction may occur immediately upon re-exposure or after
multiple exposures over time. As a result, people who have
noticed only mild allergic reactions, or no reactions at all,
may suddenly find themselves very sensitive to particular
allergens. Some diseases, like humidifier fever, are associated
with exposure to toxins from microorganisms that can grow in
large building ventilation systems. However, these diseases can
also be traced to microorganisms that grow in home heating and
cooling systems and humidifiers. Children, elderly people, and
people with breathing problems, allergies, and lung diseases are
particularly susceptible to disease-causing biological agents in
the indoor air. Mold, dust mites, pet dander, and pest droppings
or body parts can trigger asthma. Biological contaminants,
including molds and pollens can cause allergic reactions for a
significant portion of the population. Tuberculosis, measles,
staphylococcus infections, Legionella and influenza are known to
be transmitted by air.
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
What are Combustion Pollutants?
Combustion pollutants are gases or particles that
come from burning materials. The combustion pollutants come from
burning fuels in appliances. 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.
Where do Combustion Pollutants Come From?
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, wood burning, and soldering. Combustion pollutants can
also come from vented or un-vented 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
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.
Un-vented appliances do not vent to the outside, so they release
combustion pollutants directly into the home. Look at the box
below for typical appliance problems that cause the release of
pollutants in your home. Many of these problems are hard for a
homeowner to identify. A professional is needed.
What are the Health Effects of Combustion Pollutants?
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
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 properly.
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
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 chemical make-up.
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.
Combustion may release other pollutants. They
include unburned hydrocarbons and aldehydes. Little is known
about the levels of these pollutants in indoor air and the
resulting health effects.
What do I do if I suspect that combustion pollutants are
affecting my health?
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. 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.
How can I reduce my exposure to combustion pollutants?
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. 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
Choose vented appliances whenever 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.
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 un-vented space heater,
if you consider purchasing one. They are not allowed to be
used in some communities, dwellings, or certain rooms in the
If you must replace an un-vented 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.
All new wood stoves are EPA-certified to
limit the amounts of pollutants released into the outdoor
air. For more information on selecting, installing,
operating, and maintaining wood burning stoves, write to the
EPA Wood Heater Program. Before buying a wood stove check
your local laws about the installation and use of wood stove
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
Keep doors open to the rest of the house from the room where
you are using an un-vented 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 is unsafe.
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
wood burning 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.
Correct Use of Appliances
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
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 wood burning 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
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 un-vented combustion heater overnight or in a
room where you are sleeping. Carbon monoxide from combustion
heaters can reach dangerous levels.
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 detectible 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 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