INDOOR AIR QUALITY
Larry R. Piercy, Extension Specialist; William E. Murphy, Associate
Professor; Elwyn Holmes, Consulting Agricultural Engineer
In the past air pollution was considered
an outdoor problem. Attention focused primarily on serious smog problems
caused by motor vehicles and industrial sources. Yet research in recent
years has found that under many circumstances the air in our homes may
not meet accepted standards set to protect the general public.
Threats to indoor air quality can come
from many sources. Radon, formaldehyde and asbestos are existing materials
in the home that may require corrective measures to limit human exposure.
Other pollutants, such as products of combustion, result from the increased
use of unvented heaters and wood stoves in the home. In addition, the rapid
increase in the number of new household chemicals and pesticides in the
past 20 years has introduced new threats to indoor air quality.
Compounding all of these pollution
sources is the effect of home weatherization which has reduced the amount
of outside air entering our homes, resulting in a concentration of pollutants.
As a consequence, indoor pollution levels are often greater than those
outdoors and in some cases may greatly exceed accepted air quality standards.
The dose of a contaminant that a person
receives is a product of the contamination concentration or level and the
time of exposure. The time of exposure is the primary difference between
workplace standards and standards for the home. Many times workers in industrial
settings are exposed to the same contaminants at levels much greater than
those accepted for indoor air quality.
Standards set to protect the industrial
worker assume exposure of a healthy adult for a limited time each day (8-10
hrs/day for 40 hrs/week). In contrast, accepted standards for indoor and
outdoor air quality are established to protect all individuals -- from
the infant to the elderly, including those with pre-existing health problems.
They also assume that some of these individuals will be exposed for 24
hours a day.
This publication offers an overview
of the more common sources that affect air quality in the home and their
potential health effects. However, keep in mind that the long-term health
effects from exposure to a mixture of these materials, even at low levels,
are not fully known. Thus, it is important to minimize exposure to potential
pollutants even if no apparent health effects are presently occurring.
While many sources of air contamination
are discussed in this publication, this should not be a cause for alarm.
Use this information to become aware of any known potential problems and
to find ways of reducing exposure.
Radon in the Home
Radon, a colorless, odorless and tasteless
radioactive gas, is found in small amounts in the earth. It is a product
of the radioactive decay of uranium and radium which are found in minute
amounts virtually everywhere. The concentration of radon at any given location
depends on local geological formations and the quantity of radioactive
When the radon gas is formed in the
ground, it tries to escape to the open air much like an air bubble under
water. The radon in the air breaks down into other substances, but at any
given time there will be a small amount that has just seeped out of the
ground. This ever-present amount is called the background level. The background
level of radon measures about 0.1 to 0.2 picocuries/liters (pCi/liter).
The unit picocurie/liter is simply a measure of radioactive emissions produced
by the decay of radon, per volume of air.
When radon breaks down, it produces
substances that are solids rather than gases. Due to their electrical charge,
these new solid components will stick to any other solid, even dust particles.
As we breathe in air containing these contaminated dust particles, the
dust and radioactive elements can become lodged in our lungs. Any further
radioactive decays will occur on the soft tissue of the lung where it has
the greatest potential for causing damage.
Radon escaping from the ground to the
open air has the least chance of harming humans. However, the concrete
floor of a building or any other solid surface will block its path to the
open air, causing it to become more concentrated below that surface. Unfortunately,
concrete floors are never perfectly airtight. They have cracks around their
perimeter or through the middle due to expansion and contraction. There
will be other openings for water lines, sewer connections, or sump pumps.
These small cracks or openings allow radon built up under the slab to leak
into the house. The tighter the house, the longer the radon remains before
it is ultimately diluted with outdoor air containing much less radon. A
crawl space under a house tends to trap less radon since much more air
circulates there than under a concrete slab.
There can be other sources of radon
as well, such as from well water. Porous rock that can hold water (an aquifer)
may also contain uranium. When the uranium breaks down to radon gas, the
radon may be absorbed by the aquifer water. Radon behaves much the same
as carbon dioxide in a carbonated soft drink that bubbles out after the
drink is opened.
As with most harmful substances, radon's
risk to health is directly proportional to the extent of exposure. It is
difficult to ever get below the background level, but you can shoot for
levels that are as low as reasonably acceptable. Based on health records
of uranium miners, the Environmental Protection Agency (EPA) has established
some rough guidelines for radon safety. The following table outlines these
WHEN THE RADON
LEVEL IS (pCi/liter)
Less than 4
4 to 20
Temporary or permanent measures should be taken to bring radon levels
to less than four. Evacuation of the home is not necessary, but the higher
The radon level, the quicker the need to respond.
20 to 100
Temporary measures should be taken within one to three months to reduce
radon levels. More permanent measures should be planned for the near future.
More than 100
In general, temporary measures should be taken within two weeks or
less to bring the radon level down. Smoking is normally discouraged. Readings
well over 100 indicate that temporary evacuation is suggested.
The radon test is usually considered
no more accurate than about ±25%. In addition, average radon levels
during summer months may be less than half of what they were in the winter,
so the variation of radon levels from month to month and the accuracy of
the test do not dictate any stricter guidelines than those above. If your
sample produced a reading of 4.7 in the middle of winter when your house
was sealed up tight, no action would be recommended since the level would
probably be well below that figure for most of the rest of the year when
windows and doors are sometimes opened for ventilation.
Another way to look at the health risk
of radon is to compare it to other common activities. Living in a home
with a radon level of 15 would be about the same as smoking a pack of cigarettes
a day. A level of 60 would be about the same as being exposed to 20,000
chest X rays a year, while 200 would be comparable to more than 60 times
the nonsmoker's risk of dying from lung cancer. Obviously the higher the
level, the more urgent it is to take action to reduce your exposure. Since
the health risk is a product of radon level and exposure time, both factors
must be considered.
Recent studies by the EPA have indicated
that the combination of radon and smoking could multiply the health risks
rather than add them together. For instance, suppose a pack-a-day smoker
with no radon exposure has a 5% chance of getting lung cancer, and a nonsmoker
exposed to 15 pCi/liter of radon also has a 5% chance of lung cancer. The
combined effect of smoking and radon exposure may be a 20-25% chance of
cancer, not 10% as it might seem by simply adding effects. EPA estimates
that 85% of all radon-related deaths may be caused by smoking and radon
exposure. Figure 1 is a best guess
at the relative causes of lung cancer deaths. While smoking is far and
away the major single cause, the combination of smoking and radon exposure
may account for more than 15% of cancer deaths from all causes.
When the radon gas breaks down and
produces small solid charged particles (called radon daughters), these
particles cling to dust or any other nearby solid material. Smoking creates
millions of these small smoke particles for the radon daughters to cling
to. The smoke particles are very small, so they can reach into the deepest
parts of the lung. A smoker, when inhaling through the cigarette, takes
a much deeper breath than normal and so takes these smoke particles laden
with radon daughters deeper into the lungs with less chance of their being
exhaled. Based on this theory, even nonsmokers who spend a lot of time
in a smoke-filled room are at greater risk due to the abundance of small
smoke particles available for the radon daughters to cling to.
The most common places for radon to
enter a home are through cracks in basement walls or slab floors, openings
around piping or drain entry points, and open sump pits. In some cases
the source may be very obvious, while in others the walls and floor may
appear tight. Caulking cracks in basement walls and floors and around drains
and sealing up open sumps should help reduce concentrations of radon gas.
Another simple means of reducing radon
levels is to ventilate your home more. While this may have limited possibilities
in the middle of winter and in the heat of August, Kentucky has five to
six months a year during which you can comfortably open windows (it doesn't
take many) and greatly reduce radon levels as well as those of other pollutants.
An alternative procedure for more severe problems is to mechanically vent
the space below the floor (called subslab suction) or the cores of concrete
Before you do anything to prevent radon
from entering your home, you should first have your home checked for high
There are two main types of radon detectors.
The cheapest and simplest is the charcoal canister. It should be placed
in some central location in the home for three to seven days and then mailed
in a sealed packet to a certified testing laboratory for analysis. The
charcoal canister can be obtained for as little as $12 (including lab analysis).
The alternative method is an alpha
track detector. This device must be in place for at least two to four weeks
(preferably several months), but it gives a more accurate long-term average
reading. The alpha track detector costs $20 to $50.
Before purchasing a test unit, be sure
that the lab analysis will be performed in an EPA approved lab. This information
will usually be prominently displayed on the test unit box or packaging
material. For best results, conduct tests during periods when the house
has been closed for several days and will remain closed for the test period.
Preliminary tests in the spring of
1987 in Kentucky by the Radiation Control Branch of the Department of Health
Services through funding from EPA found that, overall, Kentucky does not
have a severe radon problem. Out of 900 samples, only about 1% were in
the 20 to 100 range, mostly on the lower end of the scale. About 16% were
in the 4 to 20 range.
Far eastern and far western Kentucky
appear to have few occurrences of high radon levels. The regions with the
highest probabilities of having above-average radon levels are in the counties
around Mammoth Cave, in the triangle roughly bounded by Louisville, Richmond
and Cincinnati, and in the Somerset area. If you live in one of these areas,
you can get more information from your local health department about the
If you want to test your own home,
you can send a check for $12 made out to the University of Pittsburgh to:
Radon Project, University of Pittsburgh, P.O. Box 90069, Pittsburgh, PA
15224. You will receive a charcoal canister in the mail with instructions
and a return mailing packet. You will get a short lab report giving the
radon level in your home and what steps you need to take based on that
If your charcoal canister test gives
a reading well above 4, you should conduct a long-term test with an alpha
track detector. This test would give you a better idea of the average radon
level your family is exposed to on an annual basis. If this long-term reading
is well above 4, you should take steps to lower the radon level, either
by sealing your house yourself or hiring a certified radon mitigator for
more extensive work.
As with any contracted work, get more
than one estimate for radon mitigation (reduction) work. Include in the
contract a guarantee of radon reduction to be certified by an independent
radon measuring firm. If the contractor will not guarantee meeting the
agreed radon level for an agreed cost, look elsewhere. Your local health
department or Extension office are good places to check with before contracting
for any such services.
Asbestos is a mineral fiber that has
been used in an estimated 3,000 home products through the years. Asbestos
is a very durable and heat resistant material that also provides insulation
for heat and sound. Because of these insulating properties, asbestos was
commonly added to construction products including pipe insulation, roofing,
flooring materials, insulation in heat-producing appliances and in patching
compounds and textured paints. In recent years, asbestos use has declined
because of the health effects, and EPA has proposed a ban on some asbestos-containing
products and a phase-out of all others by the year 2000.
Asbestos has been shown to cause cancer
of the lung and stomach. If the small microscopic fibers of asbestos are
released into the air, they can be inhaled and become lodged in the lining
of the lungs. With repeated exposure scar tissue can develop and lead to
asbestosis, a disease of asbestos workers. After many years cancer or mesothelioma
can also develop from asbestos in the lungs.
According to experts, there is no completely
safe level of exposure to asbestos. Exposure by youngsters is a special
concern because they would carry the material in their lungs for a lifetime.
Smokers exposed to asbestos also have a greater risk of lung cancer-greater
than the risk of cancer produced by either smoking or asbestos exposure
While asbestos is present in a variety
of materials in the home, it is normally not a major source of indoor air
quality problems. However, if the materials start to deteriorate or if
remodeling activities expose or disturb the material through sawing, sanding,
etc., then it can pose a serious hazard to indoor air quality. Once the
fibers have been released, clean-up or removal of the material is costly
and time consuming. If asbestos materials do require removal, strict procedures
should always be followed to avoid contaminating the indoor home environment.
For asbestos to be a health risk, fibers
must be released from the material and inhaled. Most asbestos products
do not pose a health threat while the fibers are incorporated in the product.
The release of hazardous fibers normally occurs in two instances:
• when attempts are made to saw, sand,
scrape or break the material, or
• when the existing structure of the
material starts to deteriorate by crumbling, cracking or flaking.
Once released, the asbestos fibers
may remain in the air for up to 80 hours. Dusting, sweeping or vacuuming
will cause the fibers to become airborne again. (The filter of an ordinary
vacuum sweeper is not fine enough to trap all the tiny fibers.)
If asbestos is found in the home, it
is best not to disturb the material. If the material is in good condition
and is not disturbed, it should not pose a health threat. However, if the
asbestos shows signs of starting to deteriorate, take action before the
fibers are released. Enclose small areas with an airtight barrier, or apply
chemical sprays to coat and seal the material. These are only temporary
solutions, however. Removal is often the best but most expensive solution.
Recent studies indicate that much of
the fear about asbestos in buildings may be overblown. Of the three types
of asbestos -- chrysotile (95% of all asbestos produced), amosite (3%)and
crocidolite (1%) -- chrysotile fibers seem to be much less dangerous than
the smaller amosite and crocidolite fibers. In addition, asbestos measurements
in most buildings containing it are normally far below dangerous levels
and so do not warrant disruption for the sake of removing concealed asbestos.
Many experts are now suggesting that
regulations requiring removal of asbestos from schools be canceled in cases
where the measured asbestos level in the air is very low. This is a rapidly
evolving area that is likely to see major changes in both legislative and
legal avenues in the 1990s.
Removal of exposed or damaged asbestos
requires special precautions to prevent release of the fibers into the
home. If possible, hire a contractor who is familiar with the guidelines
for asbestos removal. Keep in mind that most home repair or renovation
contractors are generally not experienced in removal procedures. The guidelines
for safe removal include:
1. Seal off the removal area from the
rest of the house with plastic sheeting and duct tape. Avoid tracking dust
and debris into other parts of the home.
2. Use an approved respirator along
with protective gloves, hats and coveralls during removal. Wear disposable
work garments, if possible, and shower after removing the clothing.
3. Use a water spray with wetting agent
(detergent)to thoroughly wet the material. This reduces the release of
fibers into the air.
4. Seal all material in heavy plastic
bags and approved containers for disposal in an approved sanitary landfill.
Check with your local health department.
5. Thoroughly clean the confined area
with a wet mop to remove all material. Repeat the procedure after 24 hours
to ensure that all asbestos dust has been removed. Never dust, sweep or
vacuum the material. (Contractors may use specially designed vacuums for
picking up the material.)
If you suspect that a material is asbestos,
first check with a person who is familiar with asbestos products, such
as a plumber, building contractor or heating contractor or, if possible,
the person who installed the material. To confirm the presence of asbestos,
a sample can be taken and sent to an approved laboratory at a cost of $30-50.
Your local health department should have a current. list of approved laboratories.
The following is a list of asbestos
products commonly found in the home, along with appropriate precautions
for each. Unless otherwise stated, it is best to leave the material alone
if it is in good condition. If the material is deteriorating, it should
be removed following the procedures described above.
Vinyl Floor Tiles & Vinyl Sheet Flooring
Asbestos was used in floor tiles and
in the backing of sheet flooring. Fibers can be released from sanding or
cutting of tile or dry sanding or scraping of backing materials during
removal of vinyl flooring. A safe alternative is to place new flooring
directly over the old tiles or sheet.
Patching Compounds & Textured Paints
Before 1977 patching compounds and
textured paints often contained asbestos. Avoid cutting, sanding or scraping
Some large buildings, schools and a
few homes built or remodeled between 1945 and 1978 had asbestos material
either sprayed or troweled on ceilings and walls. If the material is damaged,
consider having it removed. If possible, contact the builder or contractor
to determine if the material contained asbestos. (This is a common source
of asbestos problems in schools.)
Stoves & Furnaces
Asbestos cement board, millboard and
paper were frequently used for fire protection in homes with wood-burning
stoves. Rubbing or wear of the paper or millboard can result in the release
of fibers. The asbestos cement board will probably not release fibers unless
scraped. Furnaces often used asbestos insulation and furnace cement. Updating
the heating system can result in removal or damage to this old insulation.
Some door gaskets on wood stoves may also contain asbestos that can release
fibers if they become worn.
Wall & Pipe Insulation
Hot water and steam pipes may be covered
with asbestos-containing insulation material. Pipes and furnace ducts may
also be wrapped with an asbestos "blanket" or paper tape. These materials
were manufactured from 1920 to 1972. If damage occurs to this type of material,
the current recommendation is to leave the material in place and repair
with a protective covering, such as duct tape or other commercial product.
Asbestos wall or ceiling insulation may have been used in homes constructed
between 1930 and 1950.
Some appliances such as toasters, popcorn
poppers, stoves, etc. contain parts or components with asbestos. These
have not caused problems with the exception of hair dryers which were recalled
Roofing, Shingles & Siding
Roofing shingles, siding shingles and
sheets were manufactured using asbestos and portland cement binding material.
If these are on the outside of the home, they provide little risk to human
It seems that today we are finding
more and more items that pose some danger to our health. One of these receiving
recent publicity is formaldehyde, a resin used in products that account
for about eight percent of the U.S. gross national product. Because of
the publicity, industry is taking steps to reduce the levels of exposure.
Awareness of formaldehyde problems probably reached its peak when people
began to insulate and more tightly seal their homes during the energy crisis.
Formaldehyde, a pungent, colorless
gas, is produced by the binders and glues used in many wood products, such
as particle board, plywood and paneling. Its odor can be detected at levels
less than 1 part per billion. Building materials using formaldehyde can
emit the gas for years, although there is a gradual decrease. It has been
found that increasing the humidity in the home increases the gas emission
Some sources of formaldehyde are urea
formaldehyde foam insulation, particleboard, interior grade plywood, hardwood
paneling, cabinets, furniture, some cleaning agents and solvents, along
with other products. Formaldehyde is also produced in small amounts as
a by-product of gas combustion in gas cooking and heating equipment, especially
if poorly adjusted.
Installation of urea formaldehyde foam
insulation was identified as a major source of formaldehyde complaints.
This led the Consumer Product Safety Commission to ban its use in the '70s,
but this ruling was later overturned in the courts. Although improper installation
was usually the cause of the problem, all the negative publicity resulted
in the elimination of these foams for use as home insulation.
The Consumer Product Safety Commission,
when petitioned to regulate formaldehyde emission rates in structural products
used in homes, reported there was no great risk when conventional homes
were built using conventional construction techniques. In Kentucky the
largest source of formaldehyde complaints has been associated with mobile
homes which use more particle board and plywood paneling in construction.
Manufacturers have now set voluntary standards to reduce the amount of
formaldehyde used in plywood and particle board products.
People vary greatly in their susceptibility
to formaldehyde. People with respiratory problems or allergies, infants
and the elderly usually respond more severely at lower levels. Fewer than
20% of adults may react at levels less than 0.25 parts per million (ppm).
It can be generally said that healthy adults may not show any reactions
at levels of 0.1 ppm or below. This is the level that the Consumer Product
Safety Commission believes is safe.
Formaldehyde is primarily considered
an irritant. Extensive laboratory studies with rats indicate it could be
a possible human carcinogen at very high levels. Evaluations of industrial
workers who have been exposed to high levels of formaldehyde have yielded
no measurable cancer risk. It appears that since it is such a strong irritant,
people can't tolerate being exposed to levels that would pose a possible
Identifying formaldehyde exposure effects
is not simple because the same symptoms can occur for many other reasons.
However, one should be suspicious if any of the following persist in a
home known to have items with formaldehyde: eye, nose and throat irritations,
coughing, shortness of breath; skin irritation, nausea, headaches, dizziness;
sleeping difficulty, chest or abdominal pain. A medical doctor should check
anyone with any of the above symptoms. Also, inform the doctor about any
building materials, furniture or other items in the home that might contain
formaldehyde. When a person with the above problems leaves the home for
a few days and the problem disappears, formaldehyde should be a strong
Complaints are most common in the spring
and fall when the house is closed up and indoor humidity levels are higher
than in the winter.
There is no statewide testing facility,
and one must rely on private laboratories. When tests are requested, be
aware that results vary with the location at which measurements are taken,
the home air humidity, the time of day and air temperature. For example,
more emissions occur at higher humidity and higher temperature.
Emission Removal or Reduction
The best solution is to remove the
sources of formaldehyde emissions from the home. However, this is often
expensive and/or impractical, such as removing underlayment particleboard
or foam wall insulation. Emissions can be reduced by using sealants over
the source. For walls a mylar or vinyl wallpaper or varnish may help. For
floors any sealant also helps. Adequate fresh air circulated from fans,
open windows, heat exchangers, etc. helps to remove the gases, but this
is not always practical. When buying paneling or particleboard for indoor
use, look for those that meet industry standards.
Since high humidity contributes to
higher emissions, the family needs to control humidity levels in the home.
In the case of mobile homes, long-time formaldehyde levels have been reduced
by 60-75% with ammonia fumigation. However, this must be done by an experienced
person, and the place must be thoroughly vacuumed afterward because the
treatment may produce hexamethylene tetramine which settles out as a fine
Products of Combustion
Combustion products from gas stoves,
unvented gas and kerosene heaters and gas-fired furnaces and water heaters
are all sources of indoor air pollution. The most common are the natural
products of combustion, water vapor and carbon dioxide, which are not toxic.
Others, such as carbon monoxide, are a well-recognized hazard. Other products
of combustion produced in smaller quantities are nitric oxide, nitrogen
dioxide, sulfur dioxide, formaldehyde and respirable particles (see definition
below)which are also well recognized for their health effects.
Studies show that wood- and coal-burning
stoves, fireplaces and furnaces are also sources of hydrocarbons and polycylic
organic matter. Combustion products contained in tobacco smoke are another
source of indoor air contamination.
The following is a list of the most
common products of combustion and their health effects:
Carbon monoxide gas is a very toxic
byproduct resulting from incomplete combustion. It accumulates in the blood
by replacing the oxygen and may cause headaches, dizziness, pain and tightening
of the chest, blurred vision, unconsciousness and death. The groups at
highest risk from elevated levels are the unborn, newborns and those with
heart and lung diseases.
Carbon dioxide is a product of combustion
that is not toxic but can cause headaches, dizziness, shortness of breath
and drowsiness when in high concentrations.
Nitrogen dioxide causes irritation
of the throat and eyes. High levels can lead to impaired breathing. The
long-term health effects are not well known but could cause concern, especially
Sulfur dioxide is very irritating to
eyes and throat and may constrict upper airways. People with allergies
are quite sensitive, and higher concentrations may lead to asthma attacks.
Formaldehyde causes headaches and dizziness.
It is a suspected human carcinogen.
Respirable suspended particles
Respirable suspended particles are
very fine carbon particles which, if inhaled, can be carried deep into
the lungs (larger particles are trapped before they reach the inner lungs).
They can cause respiratory problems, bronchitis and allergic reactions.
Hazardous or toxic materials, such as sulfur dioxide or radon daughters,
may become attached to these particles and be carried deep into the lungs.
The most common sources of these products
of combustion in the home are discussed below.
Gas Cooking Stoves
Increased indoor levels of carbon monoxide,
nitrogen dioxide and nitric oxide are all commonly associated with the
use of gas stoves. Improper adjustment of the gas flames can also increase
the production of carbon monoxide by 30 times. To minimize buildup of these
pollutants, keep the flame properly adjusted and use a hood and exhaust
fan with a capacity of 100 cubic feet per minute while the stove is operating.
Unvented Kerosene & Gas Space Heaters
Unvented kerosene heaters have received
much attention because of their potential for indoor air pollution. Early
models used in confined areas produced high levels of carbon monoxide,
carbon dioxide, nitrogen dioxide and sulfur dioxide that exceeded the generally
accepted indoor and outdoor air quality standards.
The levels of carbon monoxide and nitrogen
dioxide emitted by the newer heaters with multi-stage combustion units
have been greatly reduced, but the heaters are still a major source of
air contaminants. High levels of sulfur dioxide have also been a problem,
especially when inferior grades of kerosene with high sulfur content have
To minimize air contaminants with kerosene
1. Use the heater in a well-ventilated
area. In confined areas crack open a window or door as suggested by the
2. Limit use of heaters to shorter periods
of time. Use the heater as a source of supplemental heat and not as .a
primary heat source.
3. Follow proper maintenance and operating
procedures to ensure maximum efficiency and lessen air pollution.
4. Select new multi-stage heaters which
emit fewer pollutants.
5. Use only fresh, high-quality 1-K+
fuel for clean burning.
The levels of emissions from unvented
natural gas space heaters depend on their size and design and the proper
flame adjustment. In some cases the emission levels of carbon monoxide
and formaldehyde were less than those for a gas cooking stove.
To minimize effects on indoor air
quality from unvented gas heaters:
• keep the units properly adjusted
• use them in well-ventilated areas
• limit their use to short periods as
a supplemental heater rather than a primary heat source.
Wood-Burning Stoves, Furnaces & Fireplaces
While burning wood is a significant
source of both indoor and outdoor air pollution, the actual emission level
varies greatly, depending on the design and installation of the stove or
furnace. Of most concern from wood burning are carbon monoxide, nitrogen
oxides, hydrocarbons and respirable particles, including some polycyclic
organic compounds which are carcinogenic, such as benzo-a-pyrene. To reduce
indoor emission of fireplaces, use metal or glass doors to cover the opening.
Select quality airtight woodburning stoves and furnaces and follow the
manufacturer's recommended installation procedures. Be sure chimneys provide
good draft, and follow operating procedures that reduce room emissions
when tending the fire.
Smoking produces a number of air contaminants.
The two most important are respirable suspended particles and carbon monoxide.
Others are benzo-a-pyrene, nicotine, nitrosamines, acrolein and other aldehydes.
Studies of smokers' homes showed that the average concentrations of respirable
particles in the air were much higher than the outdoor level, while levels
in homes of nonsmokers were comparable to those outdoors. Likewise, carbon
monoxide levels measured in rooms where cigarettes were being smoked were
above the EPA outdoor standard for eight hours, and in some the levels
were above the accepted standard for an eight-hour-day work environment.
Increasing ventilation rates and restricting indoor smoking will help reduce
the indoor air pollution from tobacco smoke. However, since particulate
material can cling to fabric and upholstery, ventilation alone may not
reduce particulate levels as it does for other contaminants.
Gas Furnaces & Water Heaters
Properly vented gas furnaces and water
heaters are normally not a source of indoor air pollution. However, an
obstruction in the vent or a crack in the furnace heat exchanger can allow
vented gases to leak into the home with the potential for fatal levels
of carbon monoxide. In addition, when a gas water heater or natural draft
furnace starts up from a cold condition, there may be spillage of combustion
gases for some time before they are drafted up the chimney.
In tightly weatherized houses, the
use of bathroom and kitchen vent fans or the updraft of a fireplace may
depressurize the house, causing vent gas to spill or backdraft into the
home. This potential can be reduced by testing for backdrafting with the
flame of a lighter and providing fresh air supplies for the furnace and/or
fireplace. Some new high-efficiency heaters now have sealed combustion
units which prevent backdrafting.
Organic Materials ( Household Products)
Many of the chemicals in cleaning products,
polishes, glues, paint, solvents, sprays and pesticide products are toxic,
and some may be carcinogenic. However, the health effects from exposure
to a combination of these materials in low concentrations over long periods
of time are not known.
Many of these products may have warnings
on the label to use only in well-ventilated spaces. Always follow all of
the manufacturer's directions for safe use of these materials. When possible
avoid using chemicals and sprays inside the home. If they must be used
indoors, open the windows and doors during and after their use to allow
the chemicals to disperse. Any lingering odors signal the presence of the
chemical pollutant. However, a lack of odor doesn't always mean that the
pollutant is gone.
Indoor air quality should be of concern
to everyone because of the potential health effects. Although everyone
will not be immediately affected by poor quality indoor air, the long-term
health effects are not fully known. Common sense would dictate that efforts
should be made to reduce exposure to all pollutants.
If you suspect indoor air quality problems
in your home, watch for the following signs: 1) A musty smell, stuffiness,
or noticeable lingering odors, or 2) frequent headaches, respiratory irritation,
watery eyes, nausea or fatigue among occupants.
A "yes" answer to the following questions
may indicate a link between air quality and your current health problems:
1. Are symptoms reported by more than
one family member?
2. Are the irritating symptoms most
severe in family members who spend most of their time at home?
3. Are the symptoms severe in infants
or very young children?
4. Do the symptoms become less severe
when away from the home for longer periods?
5. Do the symptoms diminish when continuous
ventilation is provided?
6. Are there seasonal patterns to the
7. Are the symptoms related to moving
into a new home, remodeling, new furnishing, energy conservation measures
or the use of certain products?
For additional information on indoor
air quality, check with your county Extension office or local health department.