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Mold – Frequently Asked Questions (FAQ)


What percentage of mold inspections end up killing transactions?

Very few actually. The truth is:
• Most inspections end in favorable results for all concerned.
• Mold is everywhere and most indoor air tests end up no different than outdoor air test.
• Most molds that are detected are not toxic.
• Most mold removal jobs are minor and able to be performed by non-professionals.

How does mold develop?

Mold requires nutrients, water, oxygen and favorable temperatures to grow. Nutrients for mold are present in dead organic material such as wood, paper or fabrics; from wet construction materials including wood, concrete, drywall, carpet or wallpaper; and from some synthetic products such as paints and adhesives.

How does mold get into a building?

Mold typically enters a building one of two ways; Most often mold develops as the result of water intrusion from a flood, leaky pipe, or condensation. Unless water intrusions are effectively dealt with within 48 hours of occurrence, ensuing mold issues are almost certain. The problem is, most small plumbing leaks and condensation issues go undetected until mold becomes a problem. Even so, most mold problems are easily and inexpensively resolve in early stages. The second most common way mold enters buildings is through the air or on people, animals and objects that are brought into the building.

How does mold spread?

Surface molds spread by eating everything they come in contact with. When surface molds are disturbed they produce mold spores, which become airborne. Airborne mold spores are (similar to seeds), they reproduce more spores. Another requirement for mold to grow is moisture, although some mold species can obtain that moisture from moist air when the relative humidity is above 70 per cent.

Can you see airborne mold spores?

Only under a microscope. 250,000 spores can fit on the head of a pin. They are so light they will stay airborne as long as 8 hours in a room with zero air movement.

Can you smell airborne mold spores?

Mold spores are known to produce the same musty odors as surface molds.

Are there harmful and non-harmful molds?

There are more than 100,000 types of mold. Only a few of them can cause infection in healthy humans (emphasis on “healthy”), while other molds cause infections only in people with compromised immune systems. Most people tolerate exposure to moderate levels of many different molds without any apparent adverse health effects, while others may have severe allergic reactions to the slightest amounts.

Some molds produce powerful chemicals called "mycotoxins" that can cause illness in animals and people. Scientific knowledge about the health effects of these toxins on humans is quite limited.

Does mold affect everyone the same way?

No. Some individuals have a genetic makeup that puts them at risk for developing allergies to mold. People who have an allergy to mold, especially if they also have asthma, can become ill from exposure to a small amount of mold. Those most susceptible mold-borne illness are infants with under developed immune systems, elderly with weakened immune systems, AIDS and cancer patients, anyone whose immune system has been compromised by respiratory infections such as pneumonia, bronchitis, etc., and people who undergo harsh medical treatments such as chemotherapy.

How much mold exposure is harmful?

No one knows the answer to this question for several reasons. Individuals are very different with respect to the amount of mold exposure they can tolerate.

Measuring or estimating "exposure" levels is very difficult. "Exposure" means the amount of mold (microscopic spores and mold fragments) that gets into a person usually by breathing, but also by eating or absorption through the skin. For example, a building may have a lot of mold in the walls but very little of that mold is getting into the air stream. In that case the people working or living in that building would have little mold exposure, even though the building itself is deteriorating.

Can mold exposure cause brain damage or death?

Although some "experts" claim that individuals have brain damage or have died because of exposure to mold and especially mold toxins, there is no verifiable scientific or medical proof at this time to support these claims. Consequently it is prudent to minimize one's exposure to really moldy environments. By "really moldy" we mean where there are large visible areas of mold (more than a few square feet) or the building has a "musty" odor because of hidden mold growth. There are many epidemiological studies showing that people who live in houses with dampness have many more health problems, especially respiratory, than do people who live in dry houses. This association does not "prove" that it is the mold that is responsible for the increase in illness. However, it does support the assertion that it is not wise to live in damp, moldy buildings.

Does tighter building construction promote mold development?

Tighter building construction does not by itself promote mold growth, but tight construction combined with some poor choices in design, building materials or operations can increase the probability of mold growth. What do we mean? The tighter the building construction the less air exchange there is between the inside air and the outside air. Whatever gets into the inside air stays there longer than it would in a house with loose construction. Moisture that gets into the air from activities such as cooking, bathing and even breathing will remain in a tight house longer than it would in a loose house. That's why exhaust fans should be installed in bathrooms and kitchens and vented to the outside. Clothes dryers should also be vented to the outside.

Tight construction permits control of the air exchange between the inside and the outside and can prevent the deposition of moisture in walls and roofs. Controlling moisture, including indoor relative humidity is the key to preventing mold growth. Tight building construction when combined with source control of moisture (exhaust fans) and controlled ventilation (intentional introduction of outside air) reduces the probability of mold growth in a building. Controlled ventilation can be provided by a duct that brings outside air to the return side of the air handler of a forced air system. A timing device or fan cycler can be programmed to have the air handler turn on for a specified number of minutes each hour even when there is no call for heating or cooling. In cold climates controlled ventilation is frequently provided by a heat recovery ventilator (HRV).

Do new building materials (e.g. drywall or paper faced gypsum board) promote mold growth?

Mold needs water, a nutrient source, oxygen and favorable temperature to grow. Many species of mold love paper faced gypsum board. Why? Making paper involves the mechanical and chemical processing of wood. Paper is largely pre-digested so it is easy for mold to get nutrients from the paper. But unless there is enough moisture present mold can't grow on the paper. If paper faced gypsum board is kept dry, it can be used and still not have mold. This material is kept dry by controlling the interior relative humidity, keeping rain from entering roofs and walls, and NOT using paper faced gypsum in areas that are likely to get wet. This means no paper faced gypsum board in shower and tub areas. Cement board, mortar or non-paper faced gypsum can safely be used in these damp areas because these products do not contain nutrients to support mold growth.

Are there reliable tests to indicate the presence of mold?

Almost all of us already have two effective mold detectors: our eyes and our noses. If black or green discoloration is noticed and is in a location that is damp or had been damp, it is almost certainly mold. If a building smells musty, there probably is mold somewhere.

Typically, mold testing is done either by extracting a sample from a suspect surface, or by extracting samples of the air. Both methods are accurate when analysis is preformed properly by a qualified lab.

Is it necessary to perform sample testing with every inspection?

It depends what the objective is. If the objective is simply to locate mold and identify its source, the answer is no. Once the source of mold is identified, air sampling does not provide additional meaningful information. Conversely, if the objective is to determine the types and/or amounts of mold present, the answer is yes. Air sampling provides a wealth of information and is the only reliable way to get a “snapshot” of the indoor air quality at the time the testing occurred.

If mold is present, what's the best way to get rid of it?

The answer depends on how much mold is present and where it is located. If the mold is on furnishings or boxes simply discard the materials. Moldy materials are not considered hazardous waste; they can be sent to a regular landfill. However, it is smart to seal the mold material in heavy plastic to protect the people who handle it in transit and prevent spreading large amounts of the mold into the building as you carry the material out of it.

If the mold is on a hard surface but occupies less than 10 square feet, wash the area with and anti-fungal mildewcide (scrubbing with a brush may be necessary), then dry the area with commercial grade dehumidifiers before repainting. If you have asthma, severe allergies and a weaken immune system get someone else to do the clean up. In all situations, wear protective gear including rubber gloves, a respirator and face shield.

Larger areas (greater than 10 square feet in area) should be cleaned by someone with experience in doing this type of work. Remember, determine what caused the moisture problem and correct that problem. Otherwise, mold is likely to recur.

Is it possible to completely eliminate mold from the inside of a home or office building?

The answer depends upon what is meant by "completely eliminate mold." To keep a building completely free of mold spores requires very efficient air filtration and is only accomplished in special situations such as hospital operating rooms and manufacturing "clean rooms." Remember, mold spores are in the outside air virtually all the time and some of them will get inside buildings. However, it is possible to keep mold from growing inside a building. Moisture control is the key to controlling mold in interior spaces. Air filtration can contribute to lowering mold spores in the air but is secondary to moisture control.

Should I use bleach to get rid of mold?

No. Although bleach will kill and decolorize mold, it does not remove mold. Dead mold can still cause allergic reactions and can resurrect itself under the right conditions. The Environmental Protection Agency (EPA), the Center for Disease Control (CDC) agree that bleach or other biocides should not routinely be used to clean up mold. Only anti-microbial, anti-fungal, mildewcide cleaners should be used.

How do I know when the mold clean up is finished?

The mold cleanup is finished when there is no visible mold remaining and there is no dust or dirt remaining that could contain large amounts of mold and mold spores. Routine clearance testing for mold is not always necessary but may be required in some instances. Leaving a few mold spores behind is not a problem if the underlying moisture problem has been corrected. Remember that mold spores are virtually everywhere. Even if all mold and mold spores are removed as part of the cleanup, spores from outside will re-enter that space. The spores won't be able to grow unless water is also present.

Q: Could I be smelling toxic black mold in my home?

A: The most infamous toxic mold, stachybotrys atra, is actually quite rare, so it is unlikely that you have it, but there are plenty of other more common molds that can make people ill. And any mold can certainly be fatal to your shoes, clothing, etc!

Molds are always present in our environment, but they can become a problem in any structure if excessive water or moisture problems are not appropriately and quickly addressed. Thus, your first step should be to inform your landlord about this. Left unattended, mold can rot lumber, drywall and other building materials so it behooves a property owner to remedy the situation to avoid increasingly more costly property damage.

Also, if you believe you are experiencing mold-related health problems, you should consult your doctor to rule out other possible causes for your symptoms. If he/she determines that your health problems do stem from mold, a written physician's report may help encourage your landlord to take steps to hire the appropriate professionals to properly rectify the problem.

Molds can grow from moisture trapped inside a structure due to inadequate ventilation (a common occurrence in modern air-tight, energy-conserving construction); from a leak from a broken pipe, roof, window or wall; or water seepage from alongside or under the dwelling, which is a landscaping/drainage problem. Perhaps the original leak was already repaired months ago but undetected water flowed to a sealed cavity in another part of the house and it taken this long to grow in a closed, dark, damp environment.

The public has become increasingly aware of the health risks associated with molds. Certain sensitive people, including the elderly, young children and those with respiratory ailments, often suffer adverse affects from prolonged exposure to or increased levels of molds. Common symptoms include eye, nose and throat irritation, excessive colds, nausea, compromised immune systems and respiratory complications such as lung infections or asthma. However, completely healthy individuals with no history of allergies can also react to amplified levels of molds.

There are so very many types of molds in our environment and they are so small that visual detection may not be possible until damage has progressed to an advanced stage. Thus the first step to remedy a mold problem is to hire a certified Industrial Hygienists (IH) from an environmental testing service to take samples and analyze the results in a lab to identify all the specific molds present.

If testing reveals elevated levels of molds, the IH will write a remediation protocol for restoration contractors to follow. Remediation could be as simple as HEPA

vacuuming, washing/cleaning of the area with a biocide or diluted (10%) bleach solution, thorough drying, and encapsulation or painting. More involved remediation can require vacating the premises while the work is performed. In these cases, full containment combined with negative air pressure techniques would be used in conjunction with many other steps.

Finally, the IH will perform clearance testing to ensure that levels of molds inside the structure are lower than those outside. It is important to note that all the remediation work will be for naught if the original source of the water or moisture intrusion is not permanently rectified.

Unfortunately, just testing for molds can cost hundreds of dollars and there are no governmental agencies to oversee or require testing, abatement or remediation of molds in structures. If your landlord will not address the problem, your only recourse may be to move out. For other remedies you might consult your attorney.

If you decide to move out, avoid bringing your problems along through cross contamination. Many molds can lie dormant indefinitely, only to be reactivated by contact with moisture. Often it is not even the mold that causes problems, but rather their spores, which can become air-borne and inhaled, ingested, or transferred to other areas or objects through the heating and air system or improper handling/cleaning. Therefore, be sure to have all your belongings professionally cleaned before using them again or moving them to a new location.