How common is mold in buildings?

Molds are very common in buildings and homes. Mold will grow in places with a lot of moisture, such as around leaks in roofs, windows, or pipes, or where there has been flooding. Mold grows well on paper products, cardboard, ceiling tiles, and wood products. Mold can also grow in dust, paints, wallpaper, insulation, drywall, carpet, fabric, and upholstery. The most common indoor molds are Cladosporium, Penicillium, and Aspergillus.  We do not have precise information about how often different molds are found in buildings and homes.

How do molds get in the indoor environment and how do they grow?

Mold is found both indoors and outdoors. Mold can enter your home through open doorways, windows, vents, and heating and air conditioning systems. Mold in the air outside can also attach itself to clothing, shoes, and pets can and be carried 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.

How do molds affect people?

Exposure to damp and moldy environments may cause a variety of health effects, or none at all. Some people are sensitive to molds. For these people, exposure to molds can lead to symptoms such as stuffy nose, wheezing, and red or itchy eyes, or skin. Some people, such as those with allergies to molds or with asthma, may have more intense reactions. 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.

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.

In 2009, the World Health Organization issued additional guidance, the WHO Guidelines for Indoor Air Quality: Dampness and Mould pdf icon[PDF – 2.65 MB]external icon. Other recent studies have suggested a potential link of early mold exposure to the 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.

A link between other adverse health effects, such as acute idiopathic pulmonary hemorrhage among infants, memory loss, or lethargy, and molds, including the mold Stachybotrys chartarum  has not been proven. Further studies are needed to find out what causes acute idiopathic hemorrhage and other adverse health effects.

There is no blood test for mold.  Some physicians can do allergy testing for possible allergies to mold, but no clinically proven tests can pinpoint when or where a particular mold exposure took place.

Who is 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. Individuals with chronic respiratory disease (e.g., chronic obstructive pulmonary disorder, asthma) may experience difficulty breathing. Individuals with immune suppression are 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.

How do you get the molds out of buildings, including homes, schools, and places of employment?

Mold growing in homes and buildings indicates that there is a problem with water or moisture. This is the first problem to address.

Remove moldy items from living areas.  Once mold starts to grow in carpet, insulation, ceiling tiles, drywall, or wallboard, the only way to deal with the problem is by removal and replacement.

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.

Remove or replace carpets and upholstery that have been soaked and cannot be dried promptly.

Clean up and dry out your home thoroughly and quickly (within 24-48 hours) after any flooding.  Dig out mud and dirt.  Use a wet vacuum to remove the remaining dirt. Scrub cleanable surfaces (such as wood, tile, stone) with soapy water and a bristle brush.  Thoroughly clean all hard surfaces (such as flooring, molding, wood and metal furniture, counter-tops, and sinks) with water and dish detergent. Dry surfaces quickly and thoroughly after cleaning. If you have a fan, air conditioner or dehumidifier that wasn’t affected by flooding use it to help the surfaces dry after you finish cleaning

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.
• Small areas (such as a shower, or an area the size of a door) can often be cleaned by residents, but larger areas might need more professional help.  Always follow the manufacturer’s instructions when using bleach or any other cleaning product.

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 or on buildings and homes.

I heard about “toxic molds” and “black molds” that grow in homes and other buildings. Should I be concerned about a serious health risk to me and my family?

There is always a little mold everywhere – in the air and on many surfaces.

Certain molds are toxigenic, meaning they can produce toxins (specifically “mycotoxins”). Hazards presented by molds that may produce mycotoxins should be considered the same as other common molds that can grow in your house. Not all fungi produce mycotoxins and even those that do will not do so under all surface or environmental conditions.

Mold growth, which often looks like spots, can be many different colors, and can smell musty.  Color is not an indication of how dangerous a mold may be.  Any mold should be removed and the moisture source that helped it grow should be removed.

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.

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