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.
- 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 mold growth.
- 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, and cleaning.
- 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 frequent
condensation).
- 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, and foods.
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 .
Molds can trigger asthma episodes in
sensitive individuals with asthma. People with asthma should avoid
contact with or exposure to molds.
EPA's Asthma web site
EPA's Asthma Brochure
EPA's Mold page from
Asthma web site
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 their lungs.
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 Biologicals .
"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 exposed population."
Consult the Centers for Disease Control (CDC)
website
Stachybotrys or Stachybotrys atra (chartarum)
and health effects
The EPA publication, "A Brief
Guide to Mold, Moisture, and Your Home" , is available here in
HTML
and PDF
formats. 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
available soon.
Biological
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:
Moisture Control
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 other
surfaces.
- 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
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 weatherization for the different climates can lead to
different problems and solutions.
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
).
Should 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 and mold.
You should consider having the air
ducts in your home cleaned if:
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 resembles it.
- 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.
