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Environmental Moulds in the Home FAQ
We often receive questions about evaluation of individuals exposed (or potentially exposed) to fungi or mycotoxins. The questions typically run along the following lines. For an organized discussion of the entire issue of environmental moulds, you should start at the beginning of our environmental mycoses section and read through all the pages (including this page). However, if you are in a hurry, you can start with the short answers that follow on this page.
- I have learned that my building is contaminated with fungi. I think I may have inhaled, breathed, or touched fungus-contaminated materials or air. I am having symptoms of ______ and ______. What should I do to get checked out?
- There is fungus in my building's wall, ceiling, or floor. I can see it! What should I do to clean it up?
- I found a bright red mould growing in the bottom of a pile of damp laundry! What should I do?
- Can the fungus in my building infect me?
What are moulds?
Moulds are one of the major forms of fungi. They are found simply everywhere in the environment, both indoors and outdoors. The vast majority of the time, they are found in association with decaying organic materials such as leaves and foods. Moulds "make their living" by helping break down these organic materials so that they can be recycled and reused by other living things in the great circle of life. Thus, moulds are very important to the world's ecology.
How do they get into my house?
Moulds travel about as microscopic spores. You may think of the spores as seeds, but much smaller. They are so small that they are easily blown great distances through the air. Because of this, mould spores are found literally everywhere. For example, it is not unusual for outside air to contain 500-1,000 mould spores in every cubic meter of air.
That sounds awful! Should I be concerned?
Yes and no. For the most part, moulds don't find us, our pets, or our house to be very inviting places to live. And, our nasal passages and lungs are designed to handle those spores that we do inhale--the lung linings have very clever ways of moving the spores back out of the lungs. Thus, mould spores may be present in the air but they can only cause us trouble if we permit them to grow. On the other hand, if significant mould overgrowth occurs in the home, this can lead to damage to the structure of the home and allergies in its occupants.
Is mildew the same as mould?
Yes. This is a common term for mould overgrowth.
What about ringworm of my pets? Is that a mould? How does it fit in here?
Ringworm has nothing to do with worms and is common term for a group of moulds that cause skin and hair infections in people and animals. However, these moulds are quite different from the moulds that cause infestation of the walls and ceilings of a home. Stated more precisely, individuals species and genera of fungi have narrowly focused habitats. There are mould that specialize in living on skin, moulds that prefer wood, and so forth. The moulds that cause ringworm require skin and hair for survival. They don't attack wallboard or ceiling tiles!
What do moulds need for growth?
Two things, and two things only: food and moisture. As just discussed, there are moulds that specialize in eating just about every possible type of organic material. The most commonly found moulds indoors are Aspergillus, Alternaria, Cladosporium, and Penicillium. When provided with suitable food (e.g., a ceiling tile or some drywall) and moisture (in the form of very high humidity, condensation, or water from a leaking pipe), these genera of fungi will gladly setup housekeeping and begin to grow.
What about Stachybotrys? I've heard that it is a special problem.
The Stachybotrys story is wildly overblown. Stachybotrys is one of many moulds found in mould-infested environments, but it is not the most common mould. However, a great fuss was made over it during the period 1993-96 when it was briefly but mistakenly linked to a series of cases of pulmonary hemorrhage in infants. For more details, see our Stachybotrys-related notes on the resources page. In short, Stachybotrys can make toxins that could make one ill. However, this is also true of many other moulds and it is not clear that any one mould is worse than another in this regard. Thus, all should be treated with equal respect--your goal is a clean environment that is both free of visible mould growth and free of mould-related odors. For an excellent further discussion of this topic, see the CDC's Stachybotrys FAQ page.
How do I look for moulds in my home?
The keys are your eyes and your nose. If you can smell a mouldy, musty, or earthy odor, a fungus may be present. Likewise, you may be able to see the dark discoloration produced by mould growth. Look especially closely at areas that have been damaged by water. While not all stains are mould-related, those that are fuzzy or expanding are often due to moulds. Moulds can be many different colors, but most are green-to-black. Once you have found a spot of mould on the floor, wall, or ceiling, you must also keep in mind that there may well be mould growth that you can't see. Moulds often grow behind walls, under floor tiles, or on the top (back) of the ceiling tiles.
Should I have my home tested for moulds?
There are professional companies that can come and culture your air and walls for fungi. However, this is really not necessary for two reasons. First, these cultures will always be positive. Moulds are simply everywhere and (short of very specialized and highly filtered clean room environments), it is not possible to eliminate them. Second, moulds are only a problem if you can see or smell them.
OK, I've got some mould here. How do I clean it up?
Even before cleaning it up, you need to think about why it got there to begin with. The key is always moisture--where did it come from? While the steps that follow will get rid of the current mould infestation, this will absolutely return if you don't eliminate the source(s) of moisture. Clean and dry is the order of the day!
We discuss the issue of mould remediation (cleanup) in greater detail on another page. On that page, we offer a step-by-step approach to the basic cleanup of small areas of fungal contamination (mildew). For more extensive contamination, you should probably hire a professional firm that specializes in dealing with this problem. As a particular point area of current interest, the CDC has released a document that addresses the question of flood-damaged homes.
Eeek! It's in my laundry! What do I do with mouldy clothes?
So, you just found something growing on those gym shorts that have been sitting in the corner for rather too long? Well, you have two choices. First, you can try laundering everything in hot water with a good detergent and some bleach. If this produces clean clothes, then you're all set. The second choice is obvious--throw it out and buy some new shorts!
What about mould-infested books, papers, and photographs?
This can be frustrating, especially if the items are valuable. If you really want to save the infested items, you might want to consult with a professional cleaning firm. However, a simple answer for small numbers of infested items is to put the individual sheets in plastic bags and then photocopy them. You can freeze them to stop further growth until such time as the photocopying can be undertaken. Sometimes the freezing process will kill the fungus. The American Institute of Conservation website provides a number of useful tips and also provides contact information for professional conservators.
What about my air ducts? Do I need to have them cleaned?
This area is a source of great confusion. Although there are exceptions (aren't there always?), the general answer is no, ducts do not need to be cleaned. Cleaning them can actually shake things loose and make the situation worse! For a great discussion of this issue, please see the EPA document entitled Should You Have the Air Ducts in Your Home Cleaned? EPA 402-K-97-002.
My house became mould-contaminated and I am having it cleaned up. They tell me that there were lots of spores loose in my air. Did the spores contaminate my clothes, my sofa, and all the other stuff in my house?
This question seems to produce a lot of anxiety. While there are no firm guidelines, we tend to go with the look and sniff approached discussed on another page. In short, if it didn't get wet, doesn't look mouldy, and doesn't smell mouldy, then it is unlikely to be meaningfully contaminated. This is especially true of things non-fabric items (e.g., a wooden chair, a TV set, etc.) Conversely, big fabric-containing items that got wet and smell/look mouldy but that can't be washed or dry-cleaned (e.g., a sofa) should probably just be thrown away--cleaning them thoroughly is likely to be quite difficult.
It's gone, at least for now. How do I keep it from coming back?
Moisture is the key. As long as the moisture content is low, the fungus can't grow. Fix the leak and keep things dry. If you are into measuring things, fungal growth is generally not possible if the moisture content of material is < 15%. You also want to keep the indoor relative humidity at 30-60% or (even better) 30-50%.
If you are dealing with surfaces that are consistently moist due to condensation, you might want to try two approaches. First, you should try to eliminate the condensation. This will involved thinking about relative humidity and dew points. The Moisture, Mold, and Mildew discussion in Appendix C of the EPA's Building Air Quality: A Guide for Building Owners and Facility Managers is quite helpful. Second, you could consider treating the surface to prevent mould growth. Paints that contain agents that inhibit mould growth are available--see the Porter Paints website for examples. Look for the paints called Portersept®, Acri-Shield®, and Acri-Pro®.
What are the symptoms of mould exposure?
People vary in their sensitivity to moulds, but the most common symptoms are those due to mould allergies. Symptoms such as wheezing (difficulty with breathing), stuff nose, burning or watering eyes, dry cough, and sore throat seem particularly common. Unfortunately, these symptoms can also be due to many other things. Thus, it can be difficult to know if a mould is causing your symptoms. The best way to find out is prove to yourself that (a) getting away from the mould makes you better and (b) being exposed makes you worse. Other sorts of symptoms (headache, fever, joint aches) are much harder to relate to mould exposure.
Can these moulds infect me?
Generally not. Many of the environmental fungi are unable to tolerate the temperature of the human body. In short, you're too hot for them! And, even those that do sometimes cause infection in people (e.g., Aspergillus) usually do so only in individuals with signficant reduction in their immune function (e.g., undergoing cancer chemotherapy or taking corticosteroids). So, for most people and most of the time, the answer is no, these fungi won't produce an actual infection.
Can antibody tests be used to make a diagnosis?
Not effectively for two reasons. First, we are all constantly exposed to fungi of various sorts. As we discuss elsewhere, there are fungi in the air around us at all times. You might very well have antibody response to those fungi. This has an important implication: just because you (a) find fungus X under your refrigerator and (b) have an antibody response to fungus X doesn't mean that the antibody response is due to the fungus under your refrigerator! A second problem has to do with the relative lack of specificity of many of the antibodies against fungi. Many of the fungi are closely related and antibodies that appear to be against fungus X might actually have been induced by exposure to fungus Y. Stated more scientifically, antibodies against fungi may both lack specificity and be cross-reactive. The extent of these problems for any given test for any given antibody will vary, but the general principle is that antibody tests are of very limited utility in making a diagnosis.
I'm still worried that a mould might be making me sick. How do I get checked out?
Remember that there are two main ways that environmental fungi might make you sick. The first is the well known process of just being allergic to the fungus. For this kind of problem, one needs to see an allergist and be tested. Do keep in mind that being allergic today doesn't necessarily mean that you became allergic due to the fungus you found last night. You might have become allergic years ago, but have symptoms now due to a new exposure to the fungus.
The other way that fungi might cause disease is by mycotoxins. Here, we're not aware of any meaningful ways to make a diagnosis. We don't know of any reliable blood tests for fungal toxins, nor do we know of any tests that are specific for the effects of fungal toxins or fungus exposure. Usually the symptoms are very general in nature (e.g., a headache or fatigue).
We write separately about Sick Building Syndrome, and we encourage you to review those ideas. In short, you can try to decide if something is bothering you by getting away from it for a while. But, beyond that, we have few suggestions. If you are still concerned, a competent general physician could look for specific causes of the symptoms. But, we can otherwise suggest only that you try to reduce the amount of fungus in your environment.
We provide specific literature references on most of our pages. However, we also have a separate page devoted just to a critical summary of the mould-related literature that is readily found on the web. Check it out!
About These Pages
The material and ideas here are drawn from many sources, including our own experience. However, this is an area with few guidelines and even fewer hard facts. So, you must always apply common sense in choosing how to adapt the ideas presented here to your own situation. When in doubt, please consult with a professional. At times, there is simply no substitute for experience and personal knowledge.
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