Frequently Asked Questions
About Mold Testing:
- How are my mold samples analyzed? The
tape sample(s) are stained with a dye and then examined microscopically under high power
(400 or 500X magnification) and 1000-times magnification by an experienced, highly-trained
laboratory technologist.
- What are the advantages of tape-lift surface
sampling?
Advantage over testing by culture method: The tape lift method is
analyzed by direct microscopy. You do not need to grow the fungus in culture media to
identify it. Thus, you are able to detect both the viable (living) and non-viable (dead)
spores, both of which are important because mold spores continue to be allergenic and
toxigenic even when dead (even after being treated with a disinfectant). Additionally,
some types of mold grow much faster than other types. Slower-growers (like the black mold
Stachybotrys) may be overgrown by molds that grow much more rapidly and thus may not be
found by the culture technique. The method we use enables all spores in the sample to be
observed.
As opposed to air sampling: Air sampling gives you a snapshot view of what is in
the air at the time of testing. Intermittent or past problems may not be found. Surface
sampling gives you a better picture of what has occurred in the past and over time.
As opposed to petri dishes or settle plates: Scientists of the American
Conference of Governmental Industrial Hygienists say that settle plates do not collect
airborne particles in a way that allows you to properly evaluate conditions. Particle
settlement depends on the size (weight) of the particle size and also is influenced by air
movement. Thus, settle plates cannot provide reliable measurements. This method is not
even appropriate for determining the relative air concentrations of different
microrganisms because of the collection bias.
- What if I suspect mold but cannot find it? Look
where there has been previous water damage, where there is standing water, or where there
is a lot of humidity. Visible mold growth can sometimes be found underneath materials
where water has damaged surfaces or behind walls.(1)
- How much mold can make me sick? It depends.
For some people, a relatively small number of mold spores can cause health problems. For
other people, it may take much more. The basic rule is, if you can see or smell it, take
steps to eliminate the excess moisture, and to cleanup and remove the mold. (1)
- What symptoms do molds commonly cause? Mold
can cause illness in several ways:
Irritation: Exposure to mold can irritate the eyes, nose, and upper
breathing passages. Symptoms of irritation include burning eyes, nasal congestion,
coughing, and post-nasal drip.
Allergy: Many people become allergic to mold and develop hay fever or
asthma symptoms such as itchy, watery eyes, nasal congestion, sneezing, chest tightness,
cough and wheezing.
Toxins: Some molds create chemicals, called toxins that can cause
illness. While much remains unknown about mold toxins, it appears that some molds produce
toxins that can have effects on the skin, the respiratory system, the immune system, and
the nervous system.
Infection: Some molds can also cause infection, such as chronic sinus
infections. Other types of mold-induced infection are much less common, and occur mainly
among people with weakened immune systems. Examples of individuals
with weakened immune systems include those with HIV infection, those receiving
chemotherapy, and the elderly. Children and pregnant women may also be at increased risk.
(2)
- Are some molds more hazardous than others? Allergic
persons vary in their sensitivities to mold, both as to amount and type needed to cause
reactions. In addition, certain types of molds can produce toxins, called mycotoxins that
the mold makes to inhibit or prevent the growth of other organisms. Mycotoxins are not
always produced, and whether a mold produces mycotoxins while growing in a building
depends on what the mold is growing on, conditions such as temperature, pH, humidity or
other unknown factors. When mycotoxins are present, they occur in both living and dead
mold spores and may be present in materials that have become contaminated with molds.(1)
- What can I save? What should I toss? In general, porous substances that are growing mold, such as paper, rags,
wallboard, and rotten wood, should be bagged and thrown out. Harder materials such as
glass, plastic, or metal can be kept after they are cleaned and disinfected.
- Can air duct systems become contaminated with mold? Yes, air duct systems can become contaminated with mold, either by supporting
mold growth inside (e.g., from a dirty or clogged air conditioning pan, due to
over-humidification of system, etc.) or by being a means of circulating and distributing
spores from one location to other parts of the home.
- Should I have my ducts cleaned? That depends
on the circumstances. The EPA guide Should you Have the Air Ducts in Your Home Cleaned?
may help you to decide this or you may wish to consult a qualified environmental
professional. MOLDetect tape lift samples taken from inside a supply vent or from the
outside of a supply register can often be helpful in determining if the supply air from
the ventilation system is contaminated with mold. A good tape lift sample from the supply
duct or register will have a visible deposit of dust, but if overloaded with dust, it
becomes difficult to read under the microscope. Do not run the heater or air conditioner
if you know or suspect that it is contaminated with mold. Cleaning should be done by a NADCA certified duct
cleaning service.
- I have mold in my basement but no one ever goes down there. Can
this be a problem? Yes. It is possible that contaminants can enter
small openings in the ventilation system and be distributed to other parts of the home.
- Can ozone air cleaners improve or reduce odor or pollution
levels? Some air cleaners are designed to produce ozone. Ozone is
a strong oxidizing agent used as a disinfectant for water and sometimes to eliminate
odors. However, ozone is a known lung irritant. Symptoms associated with exposure include
cough, chest pain, and eye, nose and throat irritation. Ozone generators have been shown
to generate indoor levels above the safe limit. Furthermore, it has been demonstrated that
ozone is not effective in controlling molds and fungi, even at high concentrations far
above safe health levels. Also ozone may damage materials in the home. For these reasons,
the EPA strongly recommends that you do not use an ozone air cleaner in any occupied
residential space. (1)
- Can ozone air cleaners be used in unoccupied spaces? They are sometimes promoted to treat homes, furniture and clothing after
fires to remove smoke odors. Ozone is a strong oxidizer that will accelerate the
degradation of rubber, upholstery, paints and other materials. Hence even when used in
unoccupied areas, ozone generators can cause damage to building materials and electronic
devices.
References:
1. California Department of Health Services: Mold in My Home: What Do I
Do?
2. July 2001 EPA Mold Remediation in Schools and Commercial Buildings,
3. The Facts about
Mold: April 2001 NY Committee for Occupational Safety and Health
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