Introduction to Molds
Molds produce tiny spores to reproduce. Mold spores waft
through the indoor and outdoor air continually. When mold
spores land on a damp spot indoors, they may begin growing
and digesting whatever they are growing on in order to
survive. There are molds that can grow on wood, paper,
carpet, and foods. When excessive moisture or water
accumulates indoors, mold growth will often occur,
particularly if the moisture problem remains undiscovered or
un-addressed. 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.
Basic Mold Cleanup
The key to mold control is moisture control. It is
important to dry water damaged areas and items within 24-48
hours to prevent mold growth. If mold is a problem in your
home, clean up the mold and get rid of the excess water or
moisture. Fix leaky plumbing or other sources of water. Wash
mold off hard surfaces with detergent and water, and dry
completely. Absorbent materials (such as ceiling tiles &
carpet) that become moldy may have to be replaced.
Ten Things You Should Know About Mold
- Potential health effects and symptoms associated with
mold exposures include allergic reactions, asthma, and
other respiratory complaints.
- 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.
- If mold is a problem in your home or school, you must
clean up the mold and eliminate sources of moisture.
- Fix the source of the water problem or leak to prevent
- Reduce indoor humidity (to 30-60% ) to decrease mold
growth by: venting bathrooms, dryers, and other
moisture-generating sources to the outside; using air
conditioners and de-humidifiers; increasing ventilation;
and using exhaust fans whenever cooking, dishwashing,
- Clean and dry any damp or wet building materials and
furnishings within 24-48 hours to prevent mold growth.
- Clean mold off hard surfaces with water and detergent,
and dry completely. Absorbent materials such as ceiling
tiles, that are moldy, may need to be replaced.
- Prevent condensation: Reduce the potential for
condensation on cold surfaces (i.e., windows, piping,
exterior walls, roof, or floors) by adding insulation.
- In areas where there is a perpetual moisture problem,
do not install carpeting (i.e., by drinking fountains,
by classroom sinks, or on concrete floors with leaks or
- Molds can be found almost anywhere; they can grow on
virtually any substance, providing moisture is present.
There are molds that can grow on wood, paper, carpet,
If you have IAQ and mold issues in your school, you
should get a copy of the IAQ
Tools for Schools Kit. Mold is covered in the
IAQ Coordinator's Guide under Appendix
H - Mold and Moisture .
Asthma and Mold
Molds can trigger asthma episodes in sensitive
individuals with asthma. People with asthma should
avoid contact with or exposure to molds.
page from Asthma web site
Health and Mold
How do molds affect people?
Some people are sensitive to molds. For these people,
exposure to molds can cause symptoms such as nasal
stuffiness, eye irritation, wheezing, or skin irritation.
Some people, such as those with serious allergies to molds,
may have more severe reactions. Severe reactions may occur
among workers exposed to large amounts of molds in
occupational settings, such as farmers working around moldy
hay. Severe reactions may include fever and shortness of
breath. Some people with chronic lung illnesses, such as
obstructive lung disease, may develop mold infections in
EPA's publication, Indoor
Air Pollution: An Introduction for Health Professionals ,
assists health professionals (especially the primary care
physician) in diagnosis of patient symptoms that could be
related to an indoor air pollution problem. It addresses the
health problems that may be caused by contaminants
encountered daily in the home and office. Organized
according to pollutant or pollutant groups such as
environmental tobacco smoke, VOCs, biological pollutants,
and sick building syndrome, this booklet lists key signs and
symptoms from exposure to these pollutants, provides a
diagnostic checklist and quick reference summary, and
includes suggestions for remedial action. Also
includes references for information contained in each
section. This booklet was developed by the American Lung
Association, the American Medical Association, the U.S.
Consumer Product Safety Commission, and the EPA. EPA
Document Reference Number 402-R-94-007, 1994.
Allergic Reactions - excerpted from Indoor
Air Pollution: An Introduction for Health Professionals
section on: Animal Dander, Molds, Dust Mites, Other
"A major concern associated with exposure to
biological pollutants is allergic reactions, which range
from rhinitis, nasal congestion, conjunctival inflammation,
and urticaria to asthma. Notable triggers for these diseases
are allergens derived from house dust mites; other
arthropods, including cockroaches; pets (cats, dogs, birds,
rodents); molds; and protein-containing furnishings,
including feathers, kapok, etc. In occupational settings,
more unusual allergens (e.g., bacterial enzymes, algae) have
caused asthma epidemics. Probably most proteins of non-human
origin can cause asthma in a subset of any appropriately
Consult the Centers for
Disease Control (CDC) website
Stachybotrys or Stachybotrys atra (chartarum) and
Homes and Molds
The EPA publication, "A Brief Guide to Mold,
Moisture, and Your Home" , is available here
in HTML and
This Guide provides information and guidance for homeowners
and renters on how to clean up residential mold problems and
how to prevent mold growth. A printed version will be
Pollutants in Your Home - This document explains
indoor biological pollution, health effects of biological
pollutants, and how to control their growth and buildup. One
third to one half of all structures have damp conditions
that may encourage development of pollutants such as molds
and bacteria, which can cause allergic reactions --
including asthma -- and spread infectious diseases.
Describes corrective measures for achieving moisture control
and cleanliness. This brochure was prepared by the
American Lung Association and the U.S. Consumer Product
Safety Commission. EPA Document Reference Number
402-F-90-102, January 1990.
Moisture control is the key to mold control, the Moisture
Control Section from Biological
Pollutants in Your Home follows:
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 grow.
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 in crawlspaces to
prevent moisture from coming in from the ground. Be sure
crawlspaces are well-ventilated.
- 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
- 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 biological pollutants.
- 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 may
be 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
- 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 weatherization for
the different climates can lead to different problems
Moisture On Windows
Your humidistat is set too high if excessive moisture
collects on windows and other cold surfaces. Excess humidity
for a prolonged time can damage walls especially when
outdoor air temperatures are very low. Excess moisture
condenses on window glass because the glass is cold. Other
sources of excess moisture besides overuse of a humidifier
may be long showers, running water for other uses, boiling
or steaming in cooking, plants, and drying clothes indoors.
A tight, energy efficient house holds more moisture inside;
you may need to run a kitchen or bath ventilating fan
sometimes, or open a window briefly. Storm windows and
caulking around windows keep the interior glass warmer and
reduce condensation of moisture there.
Humidifiers are not recommended for use in buildings
without proper vapor barriers because of potential damage
from moisture buildup. Consult a building contractor to
determine the adequacy of the vapor barrier in your house.
Use a humidity indicator to measure the relative humidity in
your house. The American Society of Heating and Air
Conditioning Engineers (ASHRAE) recommends these maximum
indoor humidity levels.
Outdoor Recommended Indoor Temperature Relative Humidity
+20 F. 35%
+10 F. 30%
0 F. 25%
-10 F. 20%
-20 F. 15%
Anne Field, Extension Specialist, Emeritus, with
reference from the Association for Home Appliance
Manufacturers ( www.aham.org ).
You Have the Air Ducts in Your Home Cleaned? -
excerpt on duct cleaning and mold follows, please review the
entire document for additional information on duct cleaning
You should consider having the air ducts in your home
There is substantial visible mold growth inside hard
surface (e.g., sheet metal) ducts or on other components of
your heating and cooling system. There are several important
points to understand concerning mold detection in heating
and cooling systems:
- Many sections of your heating and cooling system may
not be accessible for a visible inspection, so ask the
service provider to show you any mold they say exists.
- You should be aware that although a substance may look
like mold, a positive determination of whether it is
mold or not can be made only by an expert and may
require laboratory analysis for final confirmation.
For about $50, some microbiology laboratories can tell
you whether a sample sent to them on a clear strip of
sticky household tape is mold or simply a substance that
- If you have insulated air ducts and the insulation
gets wet or moldy it cannot be effectively cleaned and
should be removed and replaced.
- If the conditions causing the mold growth in the first
place are not corrected, mold growth will recur.