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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.

Spore trap (non-culturable) air sampling

To capture and quantify a broad spectrum of fungal spores (both culturable and non-culturable) present in the air.

To assess whether the levels present suggest a fungal problem in the indoor locations.

Advantages and Disadvantages


Spore trap samplers are capable of capturing a majority of spores and particulate matter in the air. Consequently, it is possible to accurately characterize problem environments where spores are present but either are no longer viable or are species that do not culture well. These are two situations where culturable sampling techniques, if used alone, may miss a potential IAQ problem.

Spore traps can also be used to quantify pollen, fiberglass particles, hyphal fragments, hair, skin cells, etc., present in the air.

Samples can be analyzed immediately.


While many mold spores have a unique morphology and are identifiable by direct microscopic examination, others do not and are more difficult to identify. These latter types must be counted in broader spore groups. In certain situations, this grouping may mask an IAQ problem.

Viability is not assessed. This is not critical in most situations.

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 view of what is in the air at the time of testing.

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. 

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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