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How to Handle Your Mold Problem: An Interview with May Indoor Air Investigations, LLC

By Kristen Bosse

Please describe a little bit about your company and the services you offer.

The company investigates indoor air quality (IAQ), moisture, building odor, and mold problems in homes, schools and offices.

How did you get into this line of work?

I have a background in organic chemistry, science teaching and contracting and did home inspections for many years. In the course of thousands of inspections, I realized that indoor conditions in buildings can have a serious impact on health and that many symptom-causing problems could be identified by means of a thorough visual inspection as well as by a careful analysis of air and dust samples through microscopy. Since starting my company, I have analyzed more than 25,000 air and dust samples, but my son and I, both asthma sufferers, were my first clients. I identified sources of allergens in our home, took steps to remove these sources, and both of us experienced a major reduction in our asthma symptoms. This is a lesson I have conveyed to my own clients: the most effective (and in many cases, least costly) resolution occurs after the specific IAQ-problem sources been identified and re-mediated.

Is it common for people to not even realize that they have mold issues in their home?

In some cases, mold problems are obvious. We get many calls from people who are concerned about musty odors in a basement or other area of the home; musty odors signal the presence of mold growth. We also get calls from people who see what they think is visible mold growth, and want confirmation as well as advice on how to get rid of the mold and prevent its reoccurrence. That said, other mold problems are not so obvious. Sometimes people don't think they have a mold problem in their homes or offices, and yet I find mold growth in basement carpeting, mechanical systems, or even on furniture that has been stored in damp spaces. Whether the mold problems are obvious or not, we frequently get physician referrals for patients whose allergy symptoms cannot be alleviated by medication and the physician suspects an indoor environmental cause. Often that cause is mold growth.

What are the potential dangers of mold, for those who don't realize?

Unlike some toxins such as carbon monoxide (which causes headache, confusion and in the extreme, death), mold-spore exposure can cause a variety of different symptoms in different individuals, so the source of the symptoms is not as clear as for a contaminant such as carbon monoxide.

Given the identical mold-spore exposures in an environment, 80 out of 100 people without the genetic disposition for allergy would not experience any symptoms. Some of the other 20 individuals might experience sneezing, coughing, itching, rashes, headaches or mental confusion, etc. Some of the individuals might become symptomatic within moments of exposure, and others might not experience symptoms until hours later, so the picture can be quite confusing. Individuals who suffer immediate symptoms are more likely to recognize mold exposure as the source of their suffering, while those who only react after a few hours may not make any connection between a specific environmental exposure and their symptoms. We are not physicians, so people experiencing allergic symptoms should certainly discuss their condition with a physician.

How much does mold decrease the value of a house?

Sometimes concealed fungal problems will have a negative impact on the health of occupants, and other times have little or no impact. That said, the presence of mold or musty odors can be a real stopper in real estate transactions. The effect on the salability of the home depends on the nature of the problem. In cases where there is no obvious mold growth but there is a strong musty odor present, buyers often turn away as soon as they enter a home. In cases where there is visible mold, the impact on the price of the home will be determined by the estimate for remediation. The most common areas with negotiable mold problems are the attic and basement, though two of the biggest sources of mold-spore exposure in homes are finished basements and air conditioning systems. I find mold in nearly every basement carpet and in most central A/C systems.

For significant mold problems, the cost for the remediation can vary from $5000 to $15,000. In some homes, there are significant concealed mold or decay problems in walls and there is no easy way to detect these. Such situations can be even more expensive to remediate.

When should people consider having their houses checked for mold?

They should certainly have a mold inspection if there is a musty odor. If there has been a flood or long term leak, a mold inspection would also make sense. One very common occurrence that often triggers an IAQ investigation is when people are sick in a particular building with symptoms that might be attributable to allergen exposure, but they feel better when away, and then sick again upon return.

What should customers look for in a good mold inspection?

The least useful type of mold inspection is one that involves taking an outdoor air sample and one or two indoor samples indoors for mold spores, and comparing the results. This approach is usually useless in determining the source of a mold spore exposure, which should be the primary goal of any mold investigation. Any mold investigation should begin with a comprehensive visual walk through of the property, to identify potential mold and moisture sources. Obvious mold growth does not have to be sampled; it should be cleaned up according to accepted guidelines. Obscure sources may need to be sampled. A mold report must include suggestions for remediation, which in turn requires the identification of locations of mold growth. Spore counts alone are useless.

Is mold always something visible? What is the difference between green and black mold?

Mold growth is often invisible. The most common places for such growth are in carpets in basements and on concrete slabs and in the dust in air conditioning systems. There are over 100,000 species of mold, and many appear black, green, white, etc. A light sheen or oval spots on the bottom foot or so of walls and doors usually indicate the presence of mold growth, which remains potentially allergenic, even when dead.

Some molds produce mycotoxins, and I believe that some individuals may develop a hypersensitivity to some of the toxins. There is no way to tell how "toxic" or allergenic a mold is from its color, since so many molds have the same color. Stachybotrys chartarum has been in the news a lot and is usually referred to as "toxic black mold," but many molds, including the most common (Cladosporium molds), are black and not necessarily toxic. Any mold can produce allergenic spores, however, and this is why exposures should be limited.

What should you do if you find mold in your house?

We have written a comprehensive book, called The Mold Survival Guide, published by The Johns Hopkins University Press, which is very useful to anyone concerned about mold, including why it grows in certain locations, how to identify mold growth, how best to get rid of it, and how to avoid the mold growth from re-occurring. People have been cleaning up mold with diluted bleach for decades and depending on the location, this can be very effective. Anyone cleaning mold should wear appropriate personal protection and precautions take to limit the spread of mold spores. Some clean jobs should only be undertaken by professional "mold remediators."

What's the process like for getting rid of mold?

For anything but small clean-up jobs, containment is required. This involves isolating the cleanup area with plastic sheeting hung from ceiling to floor. Exhausts are utilized in the containment, to maintain an air pressure less than that in the surrounding areas. This should assure that that air containing spores does not flow out of the containment area into adjacent spaces, because air will only flow into, and not out of, the containment. Remediators will be wearing personal protection: gloves, plastic suits, booties, and respirators. Disposal of moldy items is not the same as disposal for a hazardous waste like asbestos, since mold grows on anything biodegradable in the environment anyway. (Any dump is full of mold!)

What is one of the most difficult services to perform that you offer?

Taking samples in attics can be very challenging due to the inaccessibility of mechanical equipment and the high temperature in the summer (in excess of 110F.) Another challenge is sampling in the homes of highly sensitized individuals, as great care must be taken. In order to take dust samples from surfaces, the surfaces are disturbed, potentially creating toxic or allergenic exposures.

What's the best way for people to get in contact with you?

Email or phone: 978-649-1055 or

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