Mold FAQ's
Questions & Answers about MOLD
- I heard about "toxic molds" that grow in homes and other buildings. Should I be concerned about a serious health risk to me and my family?
- How common is mold, including Stachybotrys chartarum (also known by its synonym Stachybotrys atra) in buildings?
- How do molds get in the indoor environment and how do they grow?
- What is Stachybotrys chartarum (Stachybotrys atra)?
- Are there any circumstances where people should vacate a home or other building because of mold?
- Who are the people who are most at risk for health problems associated with exposure to mold?
- How do you know if you have a mold problem?
- Does Stachybotrys chartarum (Stachybotrys atra) cause acute idiopathic pulmonary hemorrhage among infants?
- What if my child has acute idiopathic pulmonary hemorrhage?
- What are the potential health effects of mold in buildings and homes?
- How do you get the molds out of buildings, including homes, schools, and places of employment?
- What should people to do if they determine they have Stachybotrys chartarum (Stachybotrys atra) in their buildings or homes?
- How do you keep mold out of buildings and homes?
- I found mold growing in my home; how do I test the mold?
- A qualified environmental lab took samples of the mold in my home and gave me the results. Can CDC interpret these results?
- What's the Difference Between Mold and Mildew?
- Summary
I heard about "toxic molds" that grow in homes and other buildings. Should I be concerned about a serious health risk to me and my family?
The term "toxic mold" is not accurate. While certain molds are toxigenic, meaning they can produce toxins (specifically mycotoxins), the molds themselves are not toxic, or poisonous. Hazards presented by molds that may produce mycotoxins should be considered the same as other common molds which can grow in your house. There is always a little mold everywhere - in the air and on many surfaces. There are very few reports that toxigenic molds found inside homes can cause unique or rare health conditions such as pulmonary hemorrhage or memory loss. These case reports are rare, and a causal link between the presence of the toxigenic mold and these conditions has not been proven. A common-sense approach should be used for any mold contamination existing inside buildings and homes. The common health concerns from molds include hay fever-like allergic symptoms. Certain individuals with chronic respiratory disease (chronic obstructive pulmonary disorder, asthma) may experience difficulty breathing. Individuals with immune suppression may be at increased risk for infection from molds. If you or your family members have these conditions, a qualified medical clinician should be consulted for diagnosis and treatment. For the most part, one should take routine measures to prevent mold growth in the home.
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How common is mold, including Stachybotrys chartarum (also known by its synonym Stachybotrys atra) in buildings?
Molds are very common in buildings and homes and will grow anywhere indoors where there is moisture. The most common indoor molds are Cladosporium, Penicillium, Aspergillus, and Alternaria. We do not have precise information about how often Stachybotrys chartarum is found in buildings and homes. While it is less common than other mold species, it is not rare.
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How do molds get in the indoor environment and how do they grow?
Mold spores occur in the indoor and outdoor environments. Mold spores may enter your house from the outside through open doorways, windows, and heating, ventilation, and air conditioning systems with outdoor air intakes. Spores in the air outside also attach themselves to people and animals, making clothing, shoes, bags, and pets convenient vehicles for carrying mold indoors.
When mold spores drop on places where there is excessive moisture, such as where leakage may have occurred in roofs, pipes, walls, plant pots, or where there has been flooding, they will grow. Many building materials provide suitable nutrients that encourage mold to grow. Wet cellulose materials, including paper and paper products, cardboard, ceiling tiles, wood, and wood products, are particularly conducive for the growth of some molds. Other materials such as dust, paints, wallpaper, insulation materials, drywall, carpet, fabric, and upholstery, commonly support mold growth.
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What is Stachybotrys chartarum (Stachybotrys atra)?
Stachybotrys chartarum (also known by its synonym Stachybotrys atra) is a greenish-black mold. It can grow on material with a high cellulose and low nitrogen content, such as fiberboard, gypsum board, paper, dust, and lint. Growth occurs when there is moisture from water damage, excessive humidity, water leaks, condensation, water infiltration, or flooding. Constant moisture is required for its growth. It is not necessary, however, to determine what type of mold you may have. All molds should be treated the same with respect to potential health risks and removal.
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Are there any circumstances where people should vacate a home or other building because of mold?
These decisions have to be made individually. If you believe you are ill because of exposure to mold in a building, you should consult your physician to determine the appropriate action to take.
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Who are the people who are most at risk for health problems associated with exposure to mold?
People with allergies may be more sensitive to molds. People with immune suppression or underlying lung disease are more susceptible to fungal infections.
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How do you know if you have a mold problem?
Large mold infestations can usually be seen or smelled.
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Does Stachybotrys chartarum (Stachybotrys atra) cause acute idiopathic pulmonary hemorrhage among infants?
To date, a possible association between acute idiopathic pulmonary hemorrhage among infants and Stachybotrys chartarum (Stachybotrys atra) has not been proved. Further studies are needed to determine what causes acute idiopathic hemorrhage.
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What if my child has acute idiopathic pulmonary hemorrhage?
Parents should ensure that their children get proper medical treatment.
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What are the potential health effects of mold in buildings and homes?
Mold exposure does not always present a health problem indoors. However some people are sensitive to molds. These people may experience symptoms such as nasal stuffiness, eye irritation, wheezing, or skin irritation when exposed to molds. Some people may have more severe reactions to molds. Severe reactions may occur among workers exposed to large amounts of molds in occupational settings, such as farmers working around moldy hay. Severe reactions may include fever and shortness of breath. Immunocompromised persons and persons with chronic lung diseases like COPD are at increased risk for opportunistic infections and may develop fungal infections in their lungs.
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How do you get the molds out of buildings, including homes, schools, and places of employment?
In most cases mold can be removed from hard surfaces by a thorough cleaning with commercial products, soap and water, or a bleach solution of no more than 1 cup of bleach in 1 gallon of water. Absorbent or porous materials like ceiling tiles, drywall, and carpet may have to be thrown away if they become moldy. If you have an extensive amount of mold and you do not think you can manage the cleanup on your own, you may want to contact a professional who has experience in cleaning mold in buildings and homes. It is important to properly clean and dry the area as you can still have an allergic reaction to parts of the dead mold and mold contamination may recur if there is still a source of moisture.
If you choose to use bleach to clean up mold:
- Never mix bleach with ammonia or other household cleaners. Mixing bleach with ammonia or other cleaning products will produce dangerous, toxic fumes.
- Open windows and doors to provide fresh air.
- Wear non-porous gloves and protective eye wear.
- If the area to be cleaned is more than 10 square feet, consult the U.S. Environmental Protection Agency (EPA) guide titled Mold Remediation in Schools and Commercial Buildings. Although focused on schools and commercial buildings, this document also applies to other building types. You can get it free by calling the EPA Indoor Air Quality Information Clearinghouse at (800) 438-4318, or by going to the EPA web site at http://www.epa.gov/mold/mold_remediation.html. [external link]
- Always follow the manufacturer’s instructions when using bleach or any other cleaning product.
What should people to do if they determine they have Stachybotrys chartarum (Stachybotrys atra) in their buildings or homes?
Mold growing in homes and buildings, whether it is Stachybotrys chartarum (Stachybotrys atra) or other molds, indicates that there is a problem with water or moisture. This is the first problem that needs to be addressed. Mold growth can be removed from hard surfaces with commercial products, soap and water, or a bleach solution of no more than 1 cup of bleach in 1 gallon of water. Mold in or under carpets typically requires that the carpets be removed. Once mold starts to grow in insulation or wallboard, the only way to deal with the problem is by removal and replacement. We do not believe that one needs to take any different precautions with Stachybotrys chartarum (Stachybotrys atra), than with other molds. In areas where flooding has occurred, prompt drying out of materials and cleaning of walls and other flood-damaged items with commercial products, soap and water, or a bleach solution of no more than 1 cup of bleach in 1 gallon of water is necessary to prevent mold growth. Never mix bleach with ammonia or other household cleaners. If a home has been flooded, it also may be contaminated with sewage. (See: After a Hurricane or Flood: Cleanup of Flood Water [external link]) Moldy items should be removed from living areas.
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How do you keep mold out of buildings and homes?
As part of routine building maintenance, buildings should be inspected for evidence of water damage and visible mold. The conditions causing mold (such as water leaks, condensation, infiltration, or flooding) should be corrected to prevent mold from growing.
Specific Recommendations:
- Keep humidity level in house between 40% and 60%.
- Use air conditioner or a dehumidifier during humid months.
- Be sure the home has adequate ventilation, including exhaust fans in kitchen and bathrooms.
- Use mold inhibitors which can be added to paints.
- Clean bathroom with mold-killing products.
- Do not carpet bathrooms.
- Remove and replace flooded carpets.
I found mold growing in my home; how do I test the mold?
Generally, it is not necessary to identify the species of mold growing in a residence, and CDC does not recommend routine sampling for molds. Current evidence indicates that allergies are the type of diseases most often associated with molds. Since the reaction of individuals can vary greatly either because of the person’s susceptibility or type and amount of mold present, sampling and culturing are not reliable in determining your health risk. If you are susceptible to mold and mold is seen or smelled, there is a potential health risk; therefore, no matter what type of mold is present, you should arrange for its removal. Furthermore, reliable sampling for mold can be expensive, and standards for judging what is and what is not an acceptable or tolerable quantity of mold have not been established.
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A qualified environmental lab took samples of the mold in my home and gave me the results. Can CDC interpret these results?
Standards for judging what is an acceptable, tolerable or normal quantity of mold have not been established. If you do decide to pay for environmental sampling for molds, before the work starts, you should ask the consultants who will do the work to establish criteria for interpreting the test results. They should tell you in advance what they will do or what recommendations they will make based on the sampling results. The results of samples taken in your unique situation cannot be interpreted without physical inspection of the contaminated area or without considering the building’s characteristics and the factors that led to the present condition.
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What's the Difference Between Mold and Mildew?
In common usage, the terms "mildew" and "mold" are for the most part interchangeable. In some cases they are used in the same phrase: "mold and mildew". The terms are used to describe the physical appearance of common fungi seen growing on objects both inside and outside buildings. This includes solid surfaces such as walls, floors, ceilings, as well as fruits and vegetables (fruits and vegetables are usually referred to as "moldy"). Mold growing on a shower curtain or bathtub is generally referred to as "mildew" (note the contextual use of the term).
Mildew is a term also used by plant scientists to describe plant diseases such as powdery mildew of roses and lilac. There is a difference between the scientific use of the word mildew as it applies to plant pathology and mildew in buildings and on clothing.
Mildew on clothing may be and often includes the same mold types that that grow on building materials that we might describe as moldy. Note mildew is commonly used to describe fungal or mold growth in bathrooms and clothing. It is usually a distinction without a difference.
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Summary
In summary, Stachybotrys chartarum (Stachybotrys atra) and other molds may cause health symptoms that are nonspecific. At present there is no test that proves an association between Stachybotrys chartarum (Stachybotrys atra) and particular health symptoms. Individuals with persistent symptoms should see their physician. However, if Stachybotrys chartarum (Stachybotrys atra) or other molds are found in a building, prudent practice recommends that they be removed.
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Mold & Decay
Cleaning Flood-Damaged Homes
Information on flood insurance claims, electrical systems, food and water sanitation, carpets and rugs, and other necessary steps to take in cleaning a flood-damaged home.
Avoiding Mold Hazards in Your Water damaged Home
A water-damaged building requires special attention to avoid or correct a mold explosion. Molds produce spores spread easily through the air, and they form new mold growths (colonies) when they find the right conditions: moisture, nutrients (nearly anything organic) and a place to grow.
Mold can damage materials and health. The longer mold is allowed to grow, the greater the risk and the harder the cleanup. So as soon as the floodwaters recede and it is safe to return, don’t delay cleanup and drying.
Take photographs to document damages for insurance purposes, and get started. It is not wise to wait for the adjuster to see it in person. Most homeowners' insurance policies do not cover mold damage or mold remediation costs.
Although there is wide variation in how people are affected by mold, long-term or high exposure is unhealthy for anyone. Exposure to mold can trigger allergic reactions and asthma attacks. It may suppress the immune system or have other effects. Some types of mold can produce mycotoxins in certain conditions, which can be present in spores and fragments in the air. “Black mold” is a misleading term since many types are black.
Mold testing is not usually needed and is rarely useful to answer questions about health concerns. Some insurance companies and legal services may require sampling for documentation. Professional mold remediation contractors may test before and after cleanup to assess their efforts.
The best way to avoid mold hazards is to hire a licensed, trained and reputable water-damage and mold-remediation firm. After a flood, that may be difficult. Since many homeowners' insurance policies do not cover mold damage or mold remediation costs, many residents face having to do the cleanup themselves.
Preventing Mold Growth after Flooding
- Remove wet carpeting right away. It’s best to discard it. If the carpet is salvaged, clean, disinfect and dry it quickly. Never reuse flooded padding.
- Remove all wet insulation right away – even if wallboard appears to be dry. Wet insulation will stay wet far too long, leading to the growth of hidden, unhealthy mold and decay fungi..
- Clean with non-phosphate detergents (any phosphate residue is mold food). If you disinfect, follow directions carefully and never mix bleach with ammonia or acids (vinegar). Disinfectants can kill molds, but they do not prevent regrowth. Surfaces contaminated with sewage or floodwater should be disinfected.
- Do all you can to speed the drying of subfloors, slabs and wall framing before replacing insulation, wallboard and flooring. Use air conditioning, heaters, fans or, better yet, a dehumidifier. Water-damage restoration contractors with special equipment (dehumidifying blowers) can provide the fastest drying.
- If possible, test the moisture content of studs and sheathing (using a moisture detector) before replacing insulation. Wood should drop below 20% moisture content by weight before you close the wall.
- DO NOT use vinyl wallpaper. It will prevent further drying on the inside.
What Home Builders, Homeowners and Real Estate Agents Think About Mold
Although it is uncommon in most homes, toxic mold, also known as black mold, has become a major issue for some home builders and homeowners in the United States. The effects have run the gamut from disposal to litigation. Although the Centers for Disease Control and Prevention has reported there is no test that proves an association between black mold and particular health symptoms, a number of lawsuits have been filed against wood products manufacturers and builders claiming that human health has been compromised by exposure to mold.
Mold and mildew, which appear as woolly or powdery growth, are microscopic fungi, low forms of plant life, that live off organic matter rather than a photosynthetic process. Mold spores can be found almost anywhere; they can grow on virtually any substance, provided moisture is present. They are always present in outdoor and indoor air, and almost all organic building surfaces, including lumber, can provide nutrients to support growth.
Mold can grow equally well on inorganic materials such as concrete, glass or plastics that may have nutrients on the surface. Of the more than 100,000 species of mold, at least 1,000 varieties are common in the United States. Mold is most likely to grow in the presence of water or dampness, such as in bathrooms and basements.
In buildings, high humidity is the most common cause of mold growth. The moisture is sometimes a result of construction defects or maintenance problems such as leaking windows or roofs, failed sealant joints, inadequate or missing flashing, leaking pipes, cracks in the siding or poorly designed air-conditioning systems. Mold can grow on materials with high cellulose content such as paper facing on drywall, dropped-ceiling tiles and wood that becomes chronically moist or water-damaged because of excessive humidity, water leaks, condensation or flooding.
In 2002, LSU AgCenter researchers conducted a nationwide study to understand and compare awareness, attitudes and concerns regarding mold among home builders, new-home homeowners and real estate agents. The samples included 1) the top 500 U.S. home builders based on sales, 2) a national random sample of 1,500 new home homeowners and 3) a national random sample of 1,000 real estate agents.
The 288 respondents indicated that home cost is the most important home building, purchase or sale criterion, followed closely by resale value and energy efficiency. Being free from mold was ranked next, followed by resistance to wood-destroying insects. Respondents did not show a strong understanding of how mold forms in new construction, although home builders had the highest level of understanding. They had a higher overall level of agreement that with proper construction methods, mold is preventable in new home construction.
Only 10 percent of homeowners believe that mold is an issue in their neighborhoods. However, 35 percent of home builders and 19 percent of real estate agents said this is an issue in the homes they build or sell. More than 60 percent of respondents in all groups generally agreed that mold can be prevented if the homeowners regularly inspect their houses and quickly repair any water leaks they discover.
Respondents had a number of concerns related to mold. First ranked is “health issues for homeowners” followed by “liability/chance of being sued” (builders and real estate agents only). Although homeowner health concerns ranked first, only 24 percent of homeowner respondents identified this as an issue. Conversely, more than two-thirds of home builders and real estate agents are concerned about this issue.
When asked whom they would most trust to provide mold safety and remediation, home builders had a significantly higher level of trust for the National Association of Home Builders, builders associations and individual builders, while real estate agents had a higher level of trust for real estate agent associations, and new home homeowners trusted the Environmental Protection Agency most.
The last question in the study asked respondents if they would like to receive more information on preventing mold. All respondent groups agreed they would like to receive such information.
Keeping in mind that responses are self-reported, on average, home builders appear to be most informed about mold issues while 1ew home homeowners are least informed. Similarly, home builder respondents had the highest level of concern about mold and homeowners were least concerned.
An understanding of the mold issue from these points of view can aid private companies, public policy makers and extension professionals in developing and disseminating unbiased, useful information to these and other groups. Results indicate that overall, respondents do not have a strong understanding of how mold forms in new construction and desire information. Opinions and concerns from these groups can help wood products manufacturers and home builders understand this issue and develop educational programs and strategies to illuminate customers and the general public about facts and myths about mold.
Bleach Does Kill Mold – Within Limits
News Release Distributed 11/30/05
Stories are hitting the media saying bleach doesn’t work in mold cleanup and prevention. An LSU AgCenter expert says there are reasons for some of the confusion but that bleach is effective at killing mold.
"What people are hearing is both true and false," said Dr. Claudette Reichel, a housing specialist with the LSU AgCenter.
Bleach is convenient, inexpensive and appropriate as a sanitizer for hard, non-porous, non-metallic and color-fast items after they have been cleaned, but it has some limitations when cleaning flooded buildings, Reichel stressed.
"Bleach can kill mold," Reichel said. "But if the surface is dirty, the bleach can get ‘spent’ oxidizing the organics and not get a chance to penetrate the mold structure enough to kill it."
That’s one reason it’s important to clean first and then disinfect, Reichel said. It’s also important to use a solution that’s strong enough – generally 1/2 to 1 cup of bleach per gallon of water – and to leave it on long enough to work – about 30 minutes.
Residual mold spores should then be removed, since killing them does not eliminate their potential health effects or toxicity – if they produced toxins, Reichel advised.
The housing specialist also explained that bleach has no residual effect. In essence, it’s gone in minutes and will not remain to inhibit the growth of new mold colonies on damp materials.
"That’s why it’s so important to speed dry after disinfecting, if possible," Reichel said.
To speed dry wet materials, Reichel suggested closing windows and running air conditioning or heat, running fans and using a dehumidifier.
"If that’s not possible because you don’t have power, some sort of treatment that inhibits mold or makes the material inhospitable can help," she said. Borate treatments, with the added benefits of termite resistance, may help, along with other products that are on the market, she said.
"In addition, bleach should not be used on metals because it is corrosive," Reichel said. "It’s important not to allow bleach to contact wiring, and it should not be used in an air-conditioning or heating system."
Reichel said a fact sheet distributed by the Federal Emergency Management Agency says treatment with commercial mold removers eliminates visible evidence of mold growth on exposed surfaces and is recommended for restoring flood-damaged homes.
In addition, tests have found very little or no evidence of mold growth in the unexposed or hidden portions of the walls and that treating the unexposed portions of the walls for mold control does not appear warranted in most cases.
FEMA recommends spraying vertical surfaces using a pump-up garden sprayer with a commercial mildew remover.
For more information, including the new fact sheet "Mold Removal Guidelines for Your Flooded Home," visit the LSU AgCenter’s Web site at www.lsuagcenter.com.
