Tips on Mold Avoidance
Used by permission of the
Bayer Corporation, 1998.
Molds (sometimes called “moulds” or “mildew”)
are a diverse subgroups of fungi, a classification which also includes
mushrooms, yeasts, rusts and smuts. The term “mold” usually
refers to fungi that appear as woolly or powdery growths on stored
fruits or grow in damp areas of the home (e.g., bathrooms).
Although molds are often viewed as food spoilers and causers of
plant and human diseases, they, like bacteria, are nature’s organic
decomposers in the biotic food chain. Molds are also used
in the production of certain foods (e.g., bread, cheese, mushrooms),
alcohol, and antibiotics.
Under optimal conditions, a single mold spore
can germinate and produce a fungal colony with hundreds of thousands
of spores in 4 to 9 days. To grow and thrive a fungus requires
organic matter and water. The organic matter can almost be
any carbon-containing material, such as plant matter, cotton, wood,
hemp, wool, leather, soil, house dust or paints. Water can
be in the form of standing water, condensation, dampness, or high
humidity. Fungi can survive in humidity ranges from 0% to
100% but flourish in the 65% to 85% range. Most allergenic
molds release their spores into the atmosphere during dry conditions
(humidity below 70%); however, some allergenic fungi (certain mushrooms
and Ascomycetes) prefer an environment with high humidity for spore
Mold allergy is similar to pollen allergy
in its symptoms and treatment. However, the growth and spore
dispersal of many molds are not as seasonal as that of pollen, and
most molds can grow indoors as well as outdoors. People who
are allergic to molds may have symptoms that persist for long periods
of time, recur several times throughout the year, or are associated
with specific environments where molds flourish.
Indoor Mold Spores
Mold colonies may not be large or colorful enough
to be seen with the naked eye, but mold growth should be suspected
in the following locations:
- Areas where “musty” or “moldy” odors are
- Areas with poor circulation, such as basements,
closets, and other storage areas; closed-up cabins, summer homes
and boat cabins.
- Locations where flooding has occurred, especially
on rugs and under padding, wood floors, baseboards, paperbacked
wallboard (gypsum board), wallpaper.
- Sites where constant dampness is a problem:
leaky plumbing around toilets, under sinks and dishwashers; leaking
roofs; poorly sealed basements; inadequately ventilated bathrooms;
poorly vented clothes dryers; refrigerator drip pans; air conditioner
or dehumidifier condensate reservoirs.
- Indoor house plants and aquariums.
- Stuffed furniture, pillows, mattresses,
old stuffed toys, wool carpets, stored paper products (books,
magazines), stored clothing and bedding.
- Anywhere dust or soil accumulates in the
home. (Counts can be very high during vacuuming).
Outdoor Mold Spores
High concentrations of outdoor mold spores generally
are associated with certain conditions or situations:
Because molds can appear to be everywhere, complete
avoidance of their spores is impossible, but taking a few basic precautions
can reduce exposure considerably.
- The air is relatively free of mold spores
in the northern latitudes during periods of freezing temperatures.
- Increased mold spore concentrations can
be found in late summer and fall as annual plants die and decomposing
leaves begin to pile beneath trees and shrubs.
- High concentrations of Ascomycetes fungal
spores can occur during intermittent rains and for 3 to 4 days
after a rainstorm.
- Soaring mushroom (toadstool) spore counts
will be evident in the spring and fall, 1 to 4 days after a rainstorm.
- High mold spore counts can be found in garden
areas, decomposing leaf or plant debris piles, and compost piles,
as well as during lawn mowing and raking.
- Elevated mold spore counts can be found
in agricultural areas, especially during harvest and around barns,
silos, and baled or stacked hay.
- Mold colonies can grow on the north side
of a home, on windows next to outdoor plant debris, or on outside
walls that are covered by or adjacent to growing plants.
Indoor Mold Spore Avoidance
Fungal colonization and fungal spore densities
within the home can be decreased by altering the conditions under
which fungi thrive. Precautions include:
- Decreasing available water.
The amount of water available for mold growth can be decreased
by repairing plumbing and roofing, sealing basement walls where
they contact outside soil, removing plant and leaf litter next
to the home, and decreasing indoor moisture. Indoor humidity
can be lowered by increasing ventilation; using dehumidifiers,
silica gel, or incandescent lights in small rooms (e.g., closets);
air-conditioning; removing aquariums and indoor houseplants; and
using home mist vaporizers only infrequently.
- Elimination of organic material.
The organic materials on which molds grow indoors can be eliminated
or decreased by:
- Removing dust and soil frequently with
standard house cleaning methods (vacuum or wet mop);
- Removing older stuffed furniture, toys,
wool rugs, cotton window coverings, and stored paper products;
- Sealed clothing in plastic bags, encasing
mattresses and pillows in vinyl, discarding older mattresses
- Removing indoor houseplants, wicker baskets,
just and hemp products;
- Using synthetic (e.g., vinyl, plastic)
furnishings and textiles for home decoration;
- Cleaning refrigerator drip pans, air-conditioner
coils and condensate pans, and dehumidifier reservoirs frequently;
- Changing filters in forced air systems
- Use of fungicides. Fungicides
intended for agricultural or nursery use can be used sparingly
outside the home with the advice of a nurseryman or agricultural
agent. Unfortunately, there are no long-lasting, safe
fungicides that can be used inside the home. Common household
germicides (e.g., Lysol™ or Tylex™) can help kill many indoor
molds. Ordinary bleach, at 50% to full strength, can decontaminate
basement and bathroom floors and walls as well as other areas
where bleach will not damage home furnishings or paint.
Special mold retardants are available as paint additives and can
be purchased through retail paint suppliers.
- Air filtration. Air filtration,
either as part of an existing forced air system or as a portable
single room system, has been shown to be very effective in lowering
indoor spore and pollen densities. Two recommended types
include high efficiency mechanical filtration or electronic precipitation
filtration, either of which can be obtained through local heating
and air-conditioning suppliers.
Outdoor Mold Spore Avoidance
Exposure to high concentrations of outdoor mold
spores can be reduced by:
- Avoiding piles of leaves and decaying vegetation,
gardens, compost piles, and other areas associated with high mold
- Removing dense vegetation or plant debris
from areas close to outside walls or windows of the home.
- Avoiding lawn mowing or raking.
- Avoiding agricultural areas (especially
at harvest time), barns, stored grains, stacked hay.
- Limiting the amount of time spent outdoors
during times of high mold spore concentrations; wearing a face
mask if necessary.
In summary, mold-sensitive individuals can decrease their
exposure to allergenic molds by:
- Reducing the humidity in the home
- Decreasing the amount of organic material
in the indoor environment
- Using fungicides (sparingly and only
outdoors) or common household germicides.
- Considering the use of high-efficiency air
- Avoiding outdoor areas known to be associated
with high mold spore densities
- Limiting the amount of time spent outdoors
during times of high mold counts.
of Use: The information
on this site does not constitute medical advice and is for your
general information only. We cannot be held responsible for anything
you could possibly do or say because of information on this site.
Consult your family physician or allergist for specific questions