What is Mold?
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Introduction
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The Facts About Mold: For Everyone
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What is mold?
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How does mold get into a house or building?
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How can I prevent mold growth?
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Can mold be toxic?
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What is “black mold”?
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Why are we concerned about mold?
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How do molds affect people?
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Who is affected by exposure to mold?
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What should I do if I see or smell mold in my home?
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Should I test my home for mold?
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Who do I call to deal with extensive mold growth in a
building?
Introduction
Mold is in the news. People are talking about its potential health
and economic impact. But what are the real risks and issues?
The available science is incomplete and sometimes controversial.
Although there are several guidance documents available, there is no
accepted national standard. Validated methods to measure
contamination are still in their infancy, and even when measurement
techniques are available, there are no clear benchmarks or standard
values to compare the results against. Similar scientific
uncertainties exist in the medical diagnosis of some mold-related
health effects.
The scientific complexities alone would be a huge challenge, but the
truth is that other difficulties dwarf them. The intense public and
media attention on this topic often creates emotionally charged
circumstances that make scientific judgment and reasoned dialogue
difficult. In some instances, building owners tend to ignore or
dismiss potentially serious problems. In other instances, building
occupants or public officials can react with excessive alarm to
perceived potential threats, complicating the scientific component
of the evaluation and making risk communication very difficult.
While experts and practitioners disagree on which trend is of more
concern, it is clear that both are real and sizable. The biggest
obstacle, however, is the amount of money that can be involved in
these disputes. As a result, the issue is increasingly clouded by
the acrimony and distorted partisanship of mushrooming liability
battles in the legal arena.
This information represents a consensus statement by a group of
experts about important aspects of the “state of the science.” The
guidance offered is practical information and does not claim to be a
definitive or comprehensive position statement. Because it is not
comprehensive, it should always be used in conjunction with other
existing guidance documents, as well as professional judgment.
Public and occupational health practice is rarely an exact science.
Prevention always poses the challenge of making tough and often
costly decisions with incomplete information or understanding.
The Facts About Mold: For Everyone
What is mold? Molds are
forms of fungi found all year round both indoors and outdoors.
Outdoors, molds live in the soil, on plants, and on dead or decaying
matter. Another common term for mold is mildew. Mold growth is
encouraged by warm and humid conditions, although it can grow during
cold weather. There are thousands of species of mold and they can be
any color. Many times, mold can be detected by a musty odor. Most
fungi, including molds, produce microscopic cells called “spores”
that spread easily through the air. Live spores act like seeds,
forming new mold growths (colonies) with the right conditions. All
of us are exposed to fungal spores daily in the air we breathe.
How does
mold get into a house or building? Most,
if not all, of the mold found indoors comes from outdoor sources. It
needs moisture to grow and becomes a problem only where there is
water damage, high humidity, or dampness. Common sources of indoor
moisture that cause mold problems include flooding, roof and
plumbing leaks, damp basements or crawl spaces, or any moisture
condensation on cold surfaces. Bathroom showers and steam from
cooking may also create problems if not well ventilated.
How can I
prevent mold growth? Con-trolling
excess moisture is the key to preventing and stopping indoor mold
growth. Keeping susceptible areas in the home clean and dry is very
important. Ventilate or use exhaust fans (vented to the outdoors) to
remove moisture where it accumulates, particularly in bathrooms,
kitchens, and laundry areas. Clothes dryers should be vented to the
outside. Repair water leaks promptly, and either dry out and clean
or replace water-damaged materials. Materials that stay wet for more
than 48 hours are likely to produce mold growth. Lowering humidity
indoors helps prevent condensation problems. To lower humidity
during humid weather, use air conditioners and dehumidifiers. Proper
exterior wall insulation helps prevent condensation from forming
inside during cold weather.
Can mold be toxic? Some molds
produce toxic substances called mycotoxins. Airborne mycotoxins have
not been shown to cause health problems for occupants in residential
or commercial buildings. The health effects of breathing mycotoxins
are not well understood and are currently under study. In rare
cases, high or chronic airborne exposures, typically associated with
certain occupations like agricultural work, have been associated
with illnesses. More is known about the health effects of consuming
moldy foods or feed containing mycotoxins than about the effects of
breathing mycotoxins.
What is “black mold”?
The news media often refer to “black mold” or “toxic black mold.” It
is usually associated with Stachybotrys chartarum, a type of
greenish-black mold commonly associated with heavy water damage. Not
all molds that appear to be black are Stachybotrys. The known health
effects from exposure to Stachybotrys are similar to other common
molds, but have been inconclusively associated with more severe
health effects in some people.
Why are we
concerned about mold? Small amounts
of mold growth in workplaces or homes (such as mildew on a shower
curtain) are not a major concern. But no mold should be allowed to
grow and multiply indoors. Large quantities of mold growth may cause
nuisance odors and health problems for some people. In addition,
mold can damage building materials, finishes, and furnishings and,
in some cases, cause structural damage to wood.
How do molds
affect people? Most people
have no reaction when exposed to molds. Allergic reactions, similar
to common pollen or animal allergies, and irritation are the most
common health effects for individuals sensitive to molds. Flu-like
symptoms and skin rash may occur. Molds may also aggravate asthma.
In rare cases, fungal infections from building-associated molds may
occur in people with serious immune disease. Most symptoms are
temporary and eliminated by correcting the mold problem.
Who is affected
by exposure to mold?
There is a wide variability in how people are affected by mold
exposure. People who may be affected more severely and quickly than
others include:
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Infants and
children
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Elderly people
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Pregnant women
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Individuals
with respiratory conditions or allergies and asthma
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Persons with
weakened immune systems (for example, chemotherapy patients,
organ or bone marrow transplant recipients, and people with HIV
infections or autoimmune diseases)
Those with special health concerns should consult their doctor if
they are concerned about mold exposure. Symptoms that may seem to
occur from mold exposure may be due to other causes, such as
bacterial or viral infections or other allergies.
What should I do if I see
or smell mold in my home?
The most important step is to identify and fix the moisture sources
causing mold growth. For small mold problems, use detergent and
water to wash mold off hard surfaces, and dry completely. Replace
moldy porous or absorbent materials (such as ceiling tiles,
wallboard, and carpeting). If you do not see mold growth but notice
a musty odor, mold may be growing behind water-damaged materials,
such as walls, carpeting, or wallpaper. Persons cleaning mold should
wear gloves, eye protection, and a dust mask or respirator to
protect against breathing airborne spores (an N95 dust mask or
respirator may be purchased in hardware stores). If you have health
concerns, you should consult your doctor before doing any mold
cleanup.
Should I test
my home for mold? Probably
not. Looking for evidence of water damage and visible mold growth
should be your first step. Testing for mold is expensive, and you
should have a clear reason for doing so. In addition, there are no
standards for “acceptable” levels of mold in the indoor environment.
When testing is done, it is usually to compare the levels and types
of mold spores found inside the home with those found outdoors. If
you know you have a mold problem, it is more important to spend time
and resources getting rid of the mold and solving the moisture
problem causing the moldy conditions.
Who do I call to deal with extensive mold growth in a building? A
professional experienced in mold evaluation and remediation, such as
an industrial hygienist, may need to be hired to address extensive
mold growth in a building. It is important to correct large mold
problems as soon as possible by first fixing the source of the
moisture problem and removing contaminated materials, then cleaning
the surfaces, and finally drying the area completely. If you use
outside contractors or professionals, make sure they have experience
cleaning up mold. Check their references, and have them follow the
recommendations and guidelines given in the information resources at
the end of this brochure.