Formaldehyde is an industrial
chemical used widely in
industry to manufacture building products, other chemicals, and
household products. In the home, formaldehyde
is used as a coating or adhesive and comes in many synthetic resin
mixtures. Some of the more common synthetic resins are
phenol-formaldehyde (PF), malamine-formaldehyde (MF), and
urea-formaldehyde (UF). UF is highly water-soluble and therefore is
the most problematic mixture for indoor air pollution.
Formaldehyde synthetics are common indoors in composite wood
products. Mobile homes are especially at risk for indoor
formaldehyde pollution because of their abundance of composite wood
in construction and relatively compact interior space.
Formaldehyde gas can also be released into the air by burning wood,
natural gas or kerosene, automobiles, and cigarettes. It can
off-gas from materials made with it and it may also occur naturally.
Pressed wood-products which may contain formaldehyde include
particle board (used in sub-flooring and shelving), hardwood plywood
paneling (used in decorative wall covering, cabinets and furniture),
and medium density fiberboard (used in drawer fronts, cabinets and
furniture tops). Medium density fiberboard is especially problematic
because it contains between 2 and 4 times as much urea-formaldehyde
as common particle board.
Another source of formaldehyde may be
carpet backing and urea-formaldehyde foam insulation (UFFI). In the
1970s, many homes were insulated with UFFI as an energy conservation
measure before it was discovered that UFFI contained dangerously
high levels of formaldehyde. Fortunately, formaldehyde emissions in
this product decline over time, so houses still using UFFI are
unlikely to have high levels of formaldehyde now. This insulation is
not very common in modern housing.
Other sources include preservatives in some paints, chemical
coatings (such as those found in the permanent press quality applied
to draperies and fabrics), and the finish texture used to coat some
All of these formaldehyde mixtures
will release dangerous formaldehyde gas into the air unless they are
properly sealed. During warmer months, problems with formaldehyde can
be especially serious as an increase in temperature of 5 to 6
degrees Celsius can double the gas's concentration. Further, an increase
in relative humidity from 30% to 70% can also cause the gas concentration
to nearly double. If both temperature and humidity increase, the
concentration of gas can rise to five times its original amount.
Early health symptoms of formaldehyde in the home include eye, nose,
and throat irritation as well as coughing and breathing
difficulties. If the problem reaches a serious level,
asthma attacks, nausea, vomiting, severe headaches, and nose bleeds
can occur. The effects of short-term exposure are relatively small,
as the health problems usually disappear once the pollutant has been
removed. However, long-term exposure increases a person's
sensitivity to the gas, increasing the probability of health
risk. Studies have shown that persons in high contact with the gas
over a long period of time (such as biological scientists or
morticians) experience a high risk of acquiring cancer. Those who
have worked with or lived around the gas for 10 or more years are
considered at high risk.
Formaldehyde has been
known to cause cancer in laboratory animals and could possibly cause
cancer in humans. There is no known maximum threshold level
and no known level below which there is not a threat of
cancer. The risk of getting cancer from formaldehyde depends
upon the amount and duration of exposure.
Formaldehyde, because of its high
danger level, is considered a potential human carcinogen and is therefore classified differently than most pollutants.
It is normally present at low levels, usually less than 0.03 ppm
(parts per million), in both indoor and outdoor air.
Levels above 0.1 ppm
can cause acute health problems such as those mentioned above. The
World Health Organization recommends that exposure should not exceed
Levels of formaldehyde
gas in the indoor air depend mainly upon  the source, 
temperature,  humidity, and  the exchange rate of air entering
or leaving the home. As temperature rises, greater amounts of
formaldehyde are emitted. When the temperature is lowered, less
formaldehyde is emitted. Formaldehyde
levels can change with the season and vary from day-to-day and
day-to-night. Levels may also increase on a hot and humid day and
decrease on a cool, dry day. Maintaining
moderate temperatures and low (30 to 50 percent) relative humidity
levels works best. Also, another
control measure is to increasing the flow of outdoor air to the
inside and vice versa so that the rate of air exchange is well
balanced. Naturally, rural
areas have lower concentrations while urban areas have higher
In wood products, the easiest way to avoid problems
with formaldehyde is to ask about the content of formaldehyde in
pressed wood products including building materials, cabinets, and
furniture before you purchase them. Try to avoid any products with
urea-formaldehyde in them. There are plenty of building materials
available which are formaldehyde free and exterior grade plywood
can be used as a substitute for particle board. Although the
exterior plywood may contain formaldehyde in some form,
urea-formaldehyde is not used in exterior products and UF is the
most problematic form of synthetic formaldehyde. Exposure
may be limited by purchasing products labeled as low-emitting or
wood products made from phenol formaldehyde, exp. OSB - oriented
strand board or softwood plywood.
If replacing the materials which
contain formaldehyde is not possible, the gas can be sealed using
either 2 coats of a water-based polyurethane sealant or a special
formaldehyde sealant. When sealing, make sure
all of the unfinished material is coated, including the undersides
of counter tops and ends of any boards. Another method of
controlling the buildup of formaldehyde in the home can be through
the use of a continuous, mechanical ventilation system to prevent
concentration levels of the gas from increasing.
Tips on how to reduce
- When purchasing pressed wood
products (particleboard, MDF, or hardwood plywood), look for
products that carry a ANSI label -American National Standards
Institute (ANSI). The following standards indicate lower
formaldehyde emission levels. (Particleboard should
conform to ANSI A208.1-1993. For particleboard flooring,
look for ANSI grades "PBU", "D2", or
"D3". MDF should comply with ANSI
A208.2-1994; and hardwood plywood with ANSI/HPVA HP-1-1994).
- Purchase furniture containing a
higher percentage of paneled, laminated, or coated
surfaces. Non-laminated panels of pressed wood products
generally emit more formaldehyde.
- Increase ventilation in the home
by opening doors and windows and installing exhaust fan(s).
- Seal non-laminated surfaces of
formaldehyde containing products with paints, varnish, or
polyurethane-like materials. Seal completely with
materials that do not contain formaldehyde. Note: some
paints and coatings emit VOCs when curing so properly ventilate
during and after treatment.