Mold |
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Molds in the Environment |
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What are molds?
Molds are fungi that
can be found both indoors and outdoors. No one knows how many species of
fungi exist but estimates range from tens of thousands to perhaps three
hundred thousand or more. Molds grow best in warm, damp, and humid
conditions, and spread and reproduce by making spores. Mold spores can
survive environmental conditions, such as dry conditions, that do not
support normal mold growth.
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What are some of the
common indoor molds?
- Cladosporium
- Penicillium
- Alternaria
- Aspergillus
- Mucor
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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, or wheezing. 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. People with chronic illnesses, such as obstructive
lung disease, may develop mold infections in their lungs.
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Where are molds
found?
Molds are found in
virtually every environment and can be detected, both indoors and
outdoors, year round. Mold growth is encouraged by warm and humid
conditions. Outdoors they can be found in shady, damp areas or places
where leaves or other vegetation is decomposing. Indoors they can be
found where humidity levels are high, such as basements or showers.
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How can people
decrease mold exposure?
Sensitive individuals
should avoid areas that are likely to have mold, such as compost piles,
cut grass, and wooded areas. Inside homes, mold growth can be slowed by
keeping humidity levels below 50% and ventilating showers and cooking
areas. Mold growth can be removed with commercial products or a weak
bleach solution (1 cup of bleach in 1 gallon of water). In situations
where mold exposure is unavoidable, sensitive people should wear a
tight-fitting face mask.
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Specific
Recommendations:
- Keep the humidity
level in the house below 50%.
- Use an air
conditioner or a dehumidifier during humid months.
- Be sure the home
has adequate ventilation, including exhaust fans in kitchen and
bathrooms.
- Add mold
inhibitors to paints before application.
- Clean bathrooms
with mold killing products.
- Do not carpet
bathrooms and basements.
- Remove or replace
previously soaked carpets and upholstery.
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What areas have high
mold exposures?
- Antique shops
- Greenhouses
- Saunas
- Farms
- Mills
- Construction areas
- Flower shops
- Summer cottages
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I found mold growing in
my home, how do I test the mold?
Generally, it is not necessary to identify the species of mold growing
in a residence, and CDC does not recommend routine sampling for molds.
Current evidence indicates that allergies are
the type of diseases most often associated with molds. Since the
susceptibility of individuals can vary greatly either because of the
amount or type of mold, sampling and culturing
are not reliable in determining your health risk. If you are susceptible
to mold and mold is seen or smelled, there is a potential health
risk; therefore, no matter what type of mold is present, you should
arrange for its removal. Furthermore, reliable sampling for mold can be
expensive, and standards for judging what is and what is not an
acceptable or tolerable quantity of
mold have not been established.
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A qualified
environmental lab took samples of the mold in my home and gave me the
results. Can CDC interpret these results?
Standards for judging what is an acceptable,
tolerable, or normal quantity of mold have not been established. If you
do decide to pay for environmental sampling for molds, before the work
starts, you should ask the consultants who will do the work to establish
criteria for interpreting the test results. They should tell you in
advance what they will do or what recommendations they will make based
on the sampling results. The results of samples taken in your unique
situation cannot be interpreted without physical inspection of the
contaminated area or without considering the building’s characteristics
and the factors that led to the present condition.
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Some additional
information on fungi and fungal diseases at the CDC Web site:
CDC/NCID Division of
Bacterial and Mycotic Diseases:
Fungal Diseases
NIOSH
publication:
HISTOPLASMOSIS: Protecting Workers at Risk
Emerging Infectious
Diseases article: "Emerging
Disease Issues and Fungal Pathogens Associated with HIV Infection"
by Neil M. Ampel, M.D. University of Arizona College of Medicine, Tucson
Veterans Affairs Medical Center, Tucson, Arizona, USA
Emerging Infectious
Diseases article: "Coccidioidomycosis:
A Reemerging Infectious Disease" by Theo N. Kirkland, M.D., and
Joshua Fierer, M.D., Departments of Pathology and Medicine, University
of California, San Diego School of Medicine and Department of Veterans
Affairs Medical Center, San Diego, California, USA
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