Mold FAQ

Where can mold be found in homes?

Although shower stalls and basements are typical moist areas prone to the growth of molds, any moist area in the home can harbor mold. Drywall, ceiling tiles, carpets, furniture, ductwork, roofing, paneling, wallpaper, and the areas around plumbing pipes are examples of areas in the home that can become infested by mold if the requisite growing conditions are present. Mold from the outdoors can enter the home through open doors, windows, and vents. It may also become attached to clothing, shoes, and pets and therefore be carried indoors. Mold can have many different colors and sometimes appears as spots. Additionally, a musty odor may be present. Mold growth may also be hidden underneath carpeting, on the back side of wallpaper, and behind drywall or paneling.

What are the health problems which may be linked to mold?

Molds produce irritating substances that may act as allergens (allergy-causing substances) in sensitive individuals. Furthermore, some molds produce toxic substances. Mold may not cause health effects or it may lead to symptoms in people who are sensitive to molds. Allergic reactions to mold are the most common health effects of mold. Allergic reactions may happen immediately or develop after a period of time following exposure. Both growing mold and mold spores may lead to allergic reactions. Symptoms of mold allergy may include sneezing, runny nose, coughing, wheezing, tearing and redness of the eyes, and skin irritation or rash. Asthma attacks may be caused by mold or mold spores in people who have asthma and are allergic to mold. Even in some non-allergic individuals, mold can irritate the eyes, skin, and airways. For example, the “black mold” known as Stachybotrys, along with some other types of mold, produces toxins known as mycotoxins that can cause irritation of the skin and airways in susceptible individuals. In some cases, people may develop severe reactions to mold exposure. Symptoms of severe reactions, which are uncommon, include fever and difficulty breathing. People with compromised immune systems or those with chronic lung disease can develop serious infections of the lungs due to molds. It is not possible to predict the degree of severity of the health risks associated with mold in the home. Allergic individuals vary in their degree of susceptibility to mold, and the risk may also depend upon the extent and exact type of mold that is present. In 2004, the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheezing in otherwise healthy people. Mold was linked to the worsening of asthma symptoms in people who have asthma. Mold was also reported to be linked to hypersensitivity pneumonitis in individuals susceptible to this immunologic condition. This uncommon disease is similar to pneumonia and can develop in susceptible individuals after brief or prolonged exposure to mold.

I heard about "toxic molds" that grow in homes and other building. Should I be concerned about a serious health risk to 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. In 2004 the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheeze in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition. The IOM also found limited or suggestive evidence linking indoor mold exposure and respiratory illness in otherwise healthy children. In 2009, the World Health Organization issued additional guidance, the WHO Guidelines for Indoor Air Quality: Dampness and Mold [PDF – 2.52 MB]. Other recent studies have suggested a potential link of early mold exposure to development of asthma in some children, particularly among children who may be genetically susceptible to asthma development, and that selected interventions that improve housing conditions can reduce morbidity from asthma and respiratory allergies, but more research is needed in this regard. 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.

How common is mold, including Stachybotrys chartarum in buildings?

Molds are very common in buildings and homes and will grow anywhere indoors where there is moisture. The most common indoors 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.

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

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.

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. In 2004 the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheeze in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition. The IOM also found limited or suggestive evidence linking indoor mold exposure and respiratory illness in otherwise healthy children.

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 by going to the EPA web site at http://www.epa.gov/mold/mold_remediation.html. Always follow the manufacturer’s instructions when using bleach or any other cleaning product.

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.

Radon FAQ

Where can mold be found in homes?

Although shower stalls and basements are typical moist areas prone to the growth of molds, any moist area in the home can harbor mold. Drywall, ceiling tiles, carpets, furniture, ductwork, roofing, paneling, wallpaper, and the areas around plumbing pipes are examples of areas in the home that can become infested by mold if the requisite growing conditions are present. Mold from the outdoors can enter the home through open doors, windows, and vents. It may also become attached to clothing, shoes, and pets and therefore be carried indoors. Mold can have many different colors and sometimes appears as spots. Additionally, a musty odor may be present. Mold growth may also be hidden underneath carpeting, on the back side of wallpaper, and behind drywall or paneling.

What are the health problems which may be linked to mold?

Molds produce irritating substances that may act as allergens (allergy-causing substances) in sensitive individuals. Furthermore, some molds produce toxic substances. Mold may not cause health effects or it may lead to symptoms in people who are sensitive to molds. Allergic reactions to mold are the most common health effects of mold. Allergic reactions may happen immediately or develop after a period of time following exposure. Both growing mold and mold spores may lead to allergic reactions. Symptoms of mold allergy may include sneezing, runny nose, coughing, wheezing, tearing and redness of the eyes, and skin irritation or rash. Asthma attacks may be caused by mold or mold spores in people who have asthma and are allergic to mold. Even in some non-allergic individuals, mold can irritate the eyes, skin, and airways. For example, the “black mold” known as Stachybotrys, along with some other types of mold, produces toxins known as mycotoxins that can cause irritation of the skin and airways in susceptible individuals. In some cases, people may develop severe reactions to mold exposure. Symptoms of severe reactions, which are uncommon, include fever and difficulty breathing. People with compromised immune systems or those with chronic lung disease can develop serious infections of the lungs due to molds. It is not possible to predict the degree of severity of the health risks associated with mold in the home. Allergic individuals vary in their degree of susceptibility to mold, and the risk may also depend upon the extent and exact type of mold that is present. In 2004, the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheezing in otherwise healthy people. Mold was linked to the worsening of asthma symptoms in people who have asthma. Mold was also reported to be linked to hypersensitivity pneumonitis in individuals susceptible to this immunologic condition. This uncommon disease is similar to pneumonia and can develop in susceptible individuals after brief or prolonged exposure to mold.

I heard about "toxic molds" that grow in homes and other building. Should I be concerned about a serious health risk to 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. In 2004 the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheeze in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition. The IOM also found limited or suggestive evidence linking indoor mold exposure and respiratory illness in otherwise healthy children. In 2009, the World Health Organization issued additional guidance, the WHO Guidelines for Indoor Air Quality: Dampness and Mold [PDF – 2.52 MB]. Other recent studies have suggested a potential link of early mold exposure to development of asthma in some children, particularly among children who may be genetically susceptible to asthma development, and that selected interventions that improve housing conditions can reduce morbidity from asthma and respiratory allergies, but more research is needed in this regard. 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.

How common is mold, including Stachybotrys chartarum in buildings?

Molds are very common in buildings and homes and will grow anywhere indoors where there is moisture. The most common indoors 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.

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

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.

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. In 2004 the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough, and wheeze in otherwise healthy people; with asthma symptoms in people with asthma; and with hypersensitivity pneumonitis in individuals susceptible to that immune-mediated condition. The IOM also found limited or suggestive evidence linking indoor mold exposure and respiratory illness in otherwise healthy children.

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 by going to the EPA web site at http://www.epa.gov/mold/mold_remediation.html. Always follow the manufacturer’s instructions when using bleach or any other cleaning product.

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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