Mold Basics
  • The key to mold control is moisture control.
  • If mold is a problem in your home, you should clean up the mold promptly and
    fix the water problem.
  • It is important to dry water-damaged areas and items within 24 to 48
    to prevent mold growth.
Why is mold
growing in my home?
Molds are part of the natural environment.  Outdoors, molds
play a part in nature by breaking down dead organic matter, such as fallen
leaves and dead trees.  But indoors, mold growth should be avoided.  Molds
reproduce by means of tiny spores; the spores are invisible to the naked eye and
float through outdoor and indoor air.  Mold may begin growing indoors when mold
spores land on surfaces that are wet.  There are many types of mold, and none of
them will grow without water or moisture.
Can mold cause health

Molds are usually
not a problem indoors, unless mold spores land on a wet or damp spot and begin
growing.  Molds have the potential to cause health problems.  Molds produce
allergens (substances that can cause allergic reactions), irritants and, in some
cases, potentially toxic substances (mycotoxins).  Inhaling or touching mold or
mold spores may cause allergic reactions in sensitive individuals.  Allergic
responses include hay fever-type symptoms, such as sneezing, runny nose, red
eyes, and skin rash (dermatitis).  Allergic reactions to mold are common.  They
can be immediate or delayed.  Molds can also cause asthma attacks in people with
asthma who are allergic to mold.  In addition, mold exposure can irritate the
eyes, skin, nose, throat and lungs of both mold-allergic and non-allergic
people.  Symptoms other than the allergic and irritant types are not commonly
reported as a result of inhaling mold.  Research on mold and health effects is
ongoing.  This article provides a brief overview; it does not describe all
potential health effects related to mold exposure.  For more detailed
information, consult a health professional.  You may also wish to consult your
state or local health department.

How do I get rid of

It is impossible to get rid of all mold and mold spores
indoors.  Some mold spores will be found floating through the air and in house
dust. Mold spores will not grow if moisture is not present.  Indoor mold growth
can and should be prevented or controlled by controlling moisture indoors. If
there is mold growth in your home, you must clean up the mold and fix the water
problem. If you clean up the mold but don’t fix the water problem, then, most
likely, the mold problem will recur.
Who should do
the cleanup?
This depends on a number of factors.  One consideration is
the size of the mold problem.  If the moldy area is less than about 10 square
feet (less than roughly a 3-foot by 3-foot patch), in most cases, you can handle
the job yourself, following the guidelines below.
  • If there has been a lot of water damage, and/or mold growth covers more than
    10 square feet, consult with your inspector.
  • If you choose to hire a contractor (or other professional service provider)
    to do the cleanup, make sure the contractor has experience cleaning up mold.
    Check references and ask the contractor to follow the recommendations of the
    EPA, the guidelines of the American Conference of Governmental Industrial
    Hygenists (ACGIH), or other guidelines from professional or government
  • Do not run the HVAC system if you know or suspect that it is contaminated
    with mold.  This could spread mold throughout the building.
  • If the water and/or mold damage was caused by sewage or other contaminated
    water, then call in a professional who has experience cleaning and fixing
    buildings damaged by contaminated water.
  • If you have health concerns, consult a health professional before starting

and Techniques

The tips and techniques presented in this section will help
you clean up your mold problem.  Professional cleaners or remediators may use
methods not covered here.  Please note that mold may cause staining and cosmetic
damage.  It may not be possible to clean an item so that its original appearance
is restored.

  • Fix plumbing leaks and other water problems as soon as possible. Dry all
    items completely.
  • Scrub mold off hard surfaces with detergent and water, and dry completely.
  • Absorbent or porous materials, such as ceiling tiles and carpet, may have to
    be thrown away if they become moldy. Mold can grow on or fill in the empty
    spaces and crevices of porous materials, so the mold may be difficult or
    impossible to remove completely.
  • Avoid exposing yourself or others to mold.
  • Do not paint or caulk moldy surfaces.
  • Clean up the mold and dry the surfaces
    before painting. Paint applied over moldy surfaces is likely to
    peel.  If you are unsure about how to clean an item, or if
    the item is expensive or of sentimental value, you may wish to consult a
    specialist. Specialists in furniture repair and restoration, painting and art
    restoration and conservation, carpet and rug cleaning, water damage, and fire or
    water restoration are commonly listed in phone books. Be sure to ask for and
    check references. Look for specialists who are affiliated with professional
Moisture and Mold Prevention
and Control Tips
  • Moisture control is the key to mold control, so when water leaks or spills
    occur indoors, ACT QUICKLY.  If wet or damp materials or areas are dried within
    24 to 48 hours after a leak or spill happens, in most cases, mold will not grow.
  • Clean and repair roof gutters regularly.
  • Make sure the ground slopes away from the building’s foundation so that
    water does not enter or collect around the foundation.
  • Keep air-conditioning drip pans clean
    and the drain lines unobstructed and flowing properly.
  • Keep indoor humidity low.  If possible, keep indoor humidity below 60%
    relative humidity (ideally, between 30% to 50%).  Relative humidity can be
    measured with a moisture or humidity meter, which is a small, inexpensive
    instrument (from $10 to $50) that is available at many hardware stores.
  • If you see condensation or moisture
    collecting on windows, walls or pipes, ACT QUICKLY to dry
    the wet surface and reduce the moisture/water source.  Condensation can be a
    sign of high humidity.

Actions that will help to reduce humidity:

  • Vent appliances that produce moisture, such as clothes dryers, stoves, and
    kerosene heaters, to the outdoors, where possible.  (Combustion appliances, such
    as stoves and kerosene heaters, produce water vapor and will increase the
    humidity unless vented to the outside.)
  • Use air conditioners and/or de-humidifiers when needed.
  • Run the bathroom fan or open the window when showering.  Use exhaust fans or
    open windows whenever cooking, running the dishwasher or dishwashing,

Testing or Sampling for Mold

Is sampling for mold needed?  In most cases, if visible mold
growth is present, sampling is unnecessary.  Since no EPA or other federal
limits have been set for mold or mold spores, sampling cannot be used to check a
building’s compliance with federal mold standards.  Surface sampling may be
useful to determine if an area has been adequately cleaned or remediated.
Sampling for mold should be conducted by professionals who have specific
experience in designing  mold sampling protocols, sampling methods, and
interpreting results.  Sample analysis should follow analytical methods
recommended by the American Industrial Hygiene Association (AIHA), the American
Conference of Governmental Industrial Hygienists (ACGIH), or other professional
Suspicion of Hidden
You may suspect hidden mold if a building smells moldy but
you cannot see the source, or if you know there has been water damage and
residents are reporting health problems. Mold may be hidden in places such as
the backside of dry wall, wallpaper or paneling, the top-side of ceiling tiles,
or the underside of carpets and pads, etc. Other possible locations of hidden
mold include areas inside walls around pipes (with leaking or condensing pipes),
the surface of walls behind furniture (where condensation forms), inside
ductwork, and in roof materials above ceiling tiles (due to roof leaks or
insufficient insulation).
Investigating Hidden
Mold Problems
Investigating hidden mold problems may be difficult and will
require caution when the investigation involves disturbing potential sites of
mold growth. For example, removal of wallpaper can lead to a massive release of
spores if there is mold growing on the underside of the paper. If you believe
that you may have a hidden mold problem, consider hiring an experienced
Cleanup and
Biocides are substances that can destroy living organisms.
The use of a chemical or biocide that kills organisms such as mold (chlorine
bleach, for example) is not recommended as a routine practice during mold
cleanup. There may be instances, however, when professional judgment may
indicate its use (for example, when immune-compromised individuals are present).
In most cases, it is not possible or desirable to sterilize an area; a
background level of mold spores will remain, and these spores will not grow if
the moisture problem has been resolved. If you choose to use disinfectants or
biocides, always ventilate the area and exhaust the air to the outdoors. Never
mix chlorine bleach with other cleaning solutions or detergents that contain
ammonia because toxic fumes could be produced.
Please note: Dead mold may still cause
allergic reactions in some people, so it is not enough to simply kill the mold;
it must also be removed.
Ten Things You Should Know About
1.  Potential health effects and symptoms
associated with mold exposure include allergic reactions, asthma, and other
respiratory complaints.
2.  There is no practical way to eliminate all
mold and mold spores in the indoor environment; the way to control indoor mold
growth is to control moisture.
3.  If mold is a problem in your home, you
must clean up the mold and eliminate sources of moisture.
4.  Fix the source of the water problem or
leak to prevent mold growth.
5.  Reduce indoor humidity (to 30% to 60%) to
decrease mold growth by:

a. venting bathrooms, dryers, and other moisture-generating
sources to the outside;
b. using air conditioners and de-humidifiers;
c. increasing ventilation; and
d. using exhaust fans whenever cooking, dishwashing, and
6.  Clean and dry any damp or wet building
materials and furnishings within 24 to 48 hours to prevent mold
7.  Clean mold off hard surfaces with water
and detergent, and dry completely. Absorbent materials that are moldy (such as
carpeting and ceiling tiles) may need to be replaced.
8.  Prevent condensation.  Reduce the
potential for condensation on cold surfaces (i.e., windows, piping, exterior
walls, roof and floors) by adding insulation.
In areas where there is a perpetual moisture problem, do not install
10.  Molds can be found almost anywhere; they
can grow on virtually any substance, provided moisture is present. There are
molds that can grow on wood, paper, carpet, and foods.
Source: DeanArringtonAssociates