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Introduction to Molds
Molds use 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.
Some common Mold
types:
Stachybotrys Chartarum (AKA Black Mold): This group of molds can thrive on water
damaged, cellulose-rich material in buildings
such as sheet rock, paper, ceiling tiles,
insulation backing, wallpaper, etc. In the
majority of cases where Stachybotrys is found
indoors, water damage has gone unnoticed
or ignored since it requires extended periods
of time with increased levels of moisture
for growth to occur. Stachybotrys is usually
black and slimy in appearance. Events of
water intrusion that are addressed quickly
tends to support the growth of more xerophilic
fungi such as Pencillium and Aspergillus.
Stachybotrys is another
fungi that has the
ability to produce
mycotoxins, ones
that
are extremely toxic,
suspected carcinogens,
and immunosuppressive.
Exposure to these
mycotoxins can result
through inhalation,
ingestion, and dermal
exposure. Symptoms
of exposure include
dermatitis, cough,
rhinitis,
nose bleeds, cold
and flu-like symptoms,
headache, general
malaise, and fever.
Aspergillus: Aspergillus is the most common genus of
fungi in our environment with more than 160
different species of mold. Sixteen of these
species have been documented as causing human
disease. Aspergillosis is now the 2nd most
common fungal infection requiring hospitalization
in the United States.
Aspergillus fumigatus.
The most encountered
species causing infection.
It is seen abundantly
in decomposing organic
material, such as
self-heating compost
piles, since it readily
grows at temperatures
up to 55 C. People
who handle contaminated
material often develop
hypersensitivity
to the spores of
Aspergillus
and may suffer severe
allergic reactions
upon exposure.
Aspergillus flavus.
The 2nd most encountered
fungi in cases of
Aspergillus infection.
It is also known
to produce the mycotoxin
aflatoxin, one of
the most potent carcinogens
known to man. In
the 1960s, 100,000
turkey
poults in Great Britain
died from ingesting
contaminated feed.
Most countries have
established
levels for aflatoxin
in food. However,
the
risks associated
with airborne exposure
are
not adequately studied
and no exposure standards
exist.
Aspergillus niger.
The 3rd most common
Aspergillus
fungi associated
with disease and
the most
common of any Aspergillus
species in nature
due to it's ability
to grow on a wide
variety
of substrates. This
species may cause
a 'fungal
ball', which is a
condition where the
fungus
actively proliferates
in the human lung,
forming a ball. It
does so without invading
the lung tissue.
Cladosporium spp: These genera of mold are pigmented dark
green to black in the front, and black on
the reverse with a velvety to powdery texture.
One of the most commonly isolated from indoor
and outdoor air, Cladosporium spp. are found
on decaying plants, woody plants, food, straw,
soil, paint, textiles, and the surface of
fiberglass duct liner in the interior of
supply ducts.
There are over 30
species in the Cladosporium
genus. The most common
are C. elatum, C.
herbarum, C. sphaerospermum,
and C. cladosporioides.
These fungi are the
causative agents
of skin
lesions, keratitis,
nail fungus, sinusitis,
asthma, and pulmonary
infections. Acute
symptoms
of exposure to Cladosporium
are edema and
bronchiospasms, and
chronic exposure
may
lead to pulmonary
emphysema.
Fusarium A common soil fungus and inhabitant on a
wide array of plants, this fungi is often
found in humidifiers and has been isolated
from water-damaged carpets and a variety
of other building materials. Human exposure
may occur through ingestion of contaminated
grains and possibly through the inhalation
of spores. Fusarium spp. are frequently involved
with eye, skin, and nail infections. More
severely it can produce hemorrhagic syndrome
(alimentary toxic aleukia) in humans which
is characterized by nausea, vomiting, diarrhea,
dermatitis, and extensive internal bleeding.
Several species can
produce the trichothecene
toxins which target
the circulatory,
alimentary,
skin, and nervous
systems. Vomitoxin
is one
such tricothecene
mycotoxin that has
been
associated with outbreaks
of acute gastrointestinal
illness in humans.
Zearalenone is another
mycotoxin produced
by Fusarium. It is
similar
in structure to the
female sex hormone
estrogen
and targets the reproductive
organs.
Penicillium: These fungi are commonly found in soil,
food, cellulose, grains, paint, carpet, wallpaper,
interior fiberglass duct insulation, and
decaying vegetation. Penicillium may cause
hypersensitivity pneumonitis, asthma, and
allergic alveolitis in susceptible individuals.
The genus Penicillium
has several species.
The most common ones
include Penicillium
chrysogenum, Penicillium
citrinum, Penicillium
janthinellum, Penicillium
marneffei, and
Penicillium purpurogenum.
This fungi has been
isolated from patients
with keratitis, ear
infections, pneumonia,
endocarditis, peritonitis,
and urinary tract
infections. Penicillium
infections are most
commonly exhibited
in immunosuppressed
individuals.
For example, P. marneffei
is a fungus abundant
in Southeast Asia
that typically infects
patients with AIDS
in this area. Infection
with P.marneffei
is acquired via inhalation
and initially results
in a pulmonary infection
and then spreads
to other areas of
the body
(lymphatic system,
liver, spleen, and
bones),
and is often fatal.
An indication of
infection
is the appearance
of papules that resemble
acne on the face,
trunk, and extremities.
Penicillim spp. do
have the ability
to produce
mycotoxins. The mycotoxin
known as Ochratoxin
A, which is nephrotoxic
and carcinogenic,
may be produced by
Penicillium verrucosum.
Verrucosidin is another
mycotoxin produced
by this fungus that
exhibits neurotoxity.
Penicillic acid is
another mycotoxin
that
is nephrotoxic (causes
kidney and liver
damage).
Mycotoxins
During the digestion of substrates, fungi
secrete enzymes into nutrients in order to
break down complex compounds into simpler
compounds that can be taken up by the fungi
and used as nutrition. These digested nutrients
produce secondary metabolic byproducts called
mycotoxins that are released to give the
fungi a competitive edge over other microorganisms
and fungi. Unfortunately, mycotoxins can
also be incredibly toxic to humans causing
a variety of responses including cold/flu-like
symptoms, sore throats, headaches, nose bleeds,
fatigue, diarrhea, dermatitis, and immune
suppression. Some mycotoxins may also be
carcinogenic and teratogenic. Molds that
have been known to potentially produce these
toxins are Acremonium, Alternaria, Aspergillus,
Chaetomium, Cladosporium, Fusarium, Penicillium,
and Stachybotrys.
Even though these molds may potentially produce
mycotoxins, they will not do so unless specific
environmental conditions exist. Currently,
it is unknown exactly what conditions promote
the growth of mycotoxin production and more
scientific research needs to be conducted
on this topic for it to be fully understood.
Top Eight Mold Mistakes
If you suspect that you're dealing with a
toxic black mold problem, it's imperative
that you avoid the some common and costly
mistakes.
Ignoring Mold Health Symptoms - Be concerned about possible mold problems
if one or more occupants is suffering from
unexplained health problems such as an ongoing
itchy eyes, bloody nose, sinus problems,
headaches, nasal congestion, runny nose,
skin rashes, skin sores, coughing, breathing
difficulties, difficulty in remembering things
and in thinking clearly, feeling disconnected
from the world around you, and/or chronic
fatigue.
Please remember that some occupants may experience
mold health symptoms, while others may have
none, with all living or working in the same
mold-infested area. People differ significantly
in their sensitivity to mold.
Ignoring Mold Clues
in the House - You contribute big-time to becoming a
mold victim when you ignore roof leaks, plumbing
leaks, sewer line leaks, water stains on
ceilings, the indoor smell of mold, visible
mold growth, high humidity (60% or more to
drive mold growth from humidity alone), a
wet or damp basement, and a wet crawl space.
Assuming There Is
No Mold Problem Because
Of No Visible Mold
Growth - The worst mold infestation problems are
often the ones you cannot see inside floors,
ceilings, walls, basement, attic, crawl space,
and the heating/cooling equipment and ducts.
Airborne mold spores are invisible to the
eye, very light, and are easily carried in
air current movements or in the air flows
of your heating/cooling system to mold cross-contaminate
your entire house from just one hidden mold
problem.
Assuming That A New Home Is Mold Free - Today's new homes often come with built-in
mold infestation problems because:
- moldy building materials are received from
the builder's supplier — today's timbers
are not kiln-dried as in earlier times, and
thus contain a high internal moisture content
that makes mold growth possible in the timbers
- the builder and its supervisors and employees
fail to do quality control to inspect for,
and thus prevent, moldy building materials
from being used in the home's construction
- the builder stores the inventory of building
materials on the outside ground with no plastic
sheeting to protect the building materials
from rain (which thus supplies the necessary
water to enable mold to grow in and on the
materials)
- the construction crew fails to cover the
entire home under construction with plastic
sheeting at the end of each construction
day to protect the building materials from
rain (which thus supplies the necessary water
to enable mold to grow in and on the materials).
The roof and side walls need to be protected
against rain until the entire roof, siding,
windows, and doors are totally installed
to seal out rain
- the builder fails to inspect and test the
home for mold growth while it is being constructed
and at the home's completion
- use of modern building materials like chip
wafer boards, drywall (plasterboard), and
plywood - all of which molds love to eat
- failure to spray all wood-based construction
materials on all surfaces with at least one
spraying of the EPA-registered fungicide
and at least one spraying of the EPA-registered
Tim-bor wood protectant
Assuming That A Dried Wet Area Is Now Mold
Safe - Mold needs moisture to grow and to multiply
as it eats your home building materials and
personal possessions. This moisture can come
from high indoor humidity, roof leaks, siding
leaks, and plumbing leaks.
If mold spores and mold colony growth run
out of moisture, they do NOT die. Instead,
they become dormant, and can wait millions
of years for access to high humidity or a
future water intrusion.
Dormant mold can make mold-sensitive persons
sick. Even the smell of dormant mold can
make some people very sick.
Using Chlorine Bleach
To Kill Mold - Do not use ineffective chlorine bleach
to try to kill mold growth and mold spores.
Bleach is too weak even when freshly manufactured
to kill mold. Bleach that sits on store shelves
and in your home continually gets ever weaker
over the passage of time. In addition, read
the manufacturer's usage directions on the
bleach container. The manufacturer does not
recommend its use to kill mold. Bleach is
NOT an EPA-registered fungicide. If you want
effective mold kill, use EPA-registered mold
fungicide.
Using Other Ineffective Products To Kill
Mold - Regular paint, paint containing a mildicide
element, any paint, Lysol, ammonia, and other
household cleaners and disinfectants. Painting
over a mold problem does not solve it - it
only hides the problem temporarily and gives
the mold something delicious to eat: the
paint itself
Ten Things You Should Know About Mold
1. Potential health effects and symptoms
associated with mold exposures include allergic
reactions, asthma, and other respiratory
complaints.
2. 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.
3 If mold is a problem
in your home or school,
you must clean up
the mold and eliminate
sources of moisture.
4. Fix the source
of the water problem
or
leak to prevent mold
growth.
5.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.
6.Clean and dry any
damp or wet building
materials and furnishings
within 24-48 hours
to prevent mold growth.
7. 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.
8. Prevent condensation:
Reduce the potential
for condensation
on cold surfaces
(i.e.,
windows, piping,
exterior walls, roof,
or
floors) by adding
insulation.
9. 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).
10. 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.
Homes and Molds
How to Identify the Cause of a Mold and Mildew
Problem
Mold and mildew are commonly found on the
exterior wall surfaces of corner rooms in
heating climate locations. An exposed
corner room is likely to be significantly
colder than adjoining rooms, so that it has
a higher relative humidity (RH) than other
rooms at the same water vapor pressure.
If mold and mildew growth are found in a
corner room, then relative humidity next
to the room surfaces is above 70%.
However, is the RH above 70% at the surfaces
because the room is too cold or because there
is too much moisture present (high water
vapor pressure)?
The amount of moisture in the room can be
estimated by measuring both temperature and
RH at the same location and at the same time.
Suppose there are two cases. In the
first case, assume that the RH is 30% and
the temperature is 70oF in the middle of the room. The low
RH at that temperature indicates that the
water vapor pressure (or absolute humidity)
is low. The high surface RH is probably
due to room surfaces that are "too cold."
Temperature is the dominating factor, and
control strategies should involve increasing
the temperature at cold room surfaces.
In the second case, assume that the RH is
50% and the temperature is 70oF in the middle of the room. The higher
RH at that temperature indicates that the
water vapor pressure is high and there is
a relatively large amount of moisture in
the air. The high surface RH is probably
due to air that is "too moist."
Humidity is the dominating factor, and control
strategies should involve decreasing the
moisture content of the indoor air.
Mold Abatement and
Remediation
The New York City Department of Health publishes
a guideline for professional mold assessment
and remediation service providers. The guideline
establishes five levels of abatement based
on size of the affected area and discusses
health protection measures for workers and
occupants. See the Reference section at the
end of this document for contact information
to acquire a copy of the guidelines.
The California Department of Health Services
also publishes clean-up procedures that are
more oriented toward homeowners. See the
Reference section for this contact information
as well. The clean-up procedures established
by this California agency recommend the use
of a disinfectant (chlorine bleach) whereas
the New York City guideline does not make
a recommendation for use of a disinfectant.
The U.S. Environmental Protection Agency
published the "Mold Remediation in Schools
and Commercial Buildings" document that
also provides guidelines and insight on clean-up
procedures.
Common suggestions among the various documents
include:
Correct the source of excessive moisture.
When handling or cleaning moldy materials,
consider using a mask or respirator for protection
against inhaling airborne spores. Respirators
can be purchased from hardware stores; select
one for particle removal (sometimes referred
to as a N95 or TC-21C particulate respirator).
Wear protective gloves, eye protection glasses,
and clothing should be immediately washed.
Take care to remove or clean contaminated
materials in a way that prevents the emission
of fungi and dust contaminated with fungi
from leaving a work area and entering an
occupied area.
Non-porous (e.g., metals, glass, and hard
plastics) and semi-porous (e.g., wood, and
concrete) materials that are structurally
sound and are visibly moldy can be cleaned
and reused.
Cleaning should be done using a detergent
solution.
Porous materials (e.g., ceiling tiles and
insulation, and wallboard) with more than
a small area of contamination should be removed
and discarded. Porous materials that can
be cleaned, can be reused, but should be
discarded if possible.
A professional restoration consultant should
be contacted when restoring porous materials
with more than a small area of fungal contamination.
All materials to be reused should be dry
and visibly free from mold.
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
| +20o F. |
35% |
| +10o F. |
30% |
| 0o F. |
25% |
| -10o F. |
20% |
| -20o F. |
15% |
Source: 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.
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