What is mold?

Mold refers to multiple types of fungi that grow in filaments and reproduce by forming spores. The term "mildew" is sometimes used to refer to some kinds of mold, particularly mold with a white or grayish color or mold growing in shower stalls and bathrooms. Mold may grow indoors or outdoors and thrives in damp, warm, and humid environments. Mold can be found in essentially any environment or season.

The most common types of mold that are found indoors include Cladosporium, Penicillium, Alternaria, and Aspergillus. Stachybotrys chartarum (also known as Stachybotrys atra and sometimes referred to as "black mold") is a greenish-black mold that can also be found indoors. Stachybotrys grows on household surfaces that have high cellulose content, such as wood, fiberboard, gypsum board, paper, dust, and lint.

Molds reproduce by forming tiny spores that not visible to the naked eye. Mold spores are very hardy and can survive under conditions in which mold cannot grow, such as in dry and harsh environments. These spores travel through outdoor and indoor air. When mold spores land on a surface where moisture is present, mold can start to grow.

Outdoors, molds play a role in the decomposition of organic matter such as dead trees, compost, and leaves. They are most common in damp, dark areas or areas of decomposing plant life. Indoors, mold is often found in basements or shower stalls. Indoor mold has the potential to cause health problems and can destroy surfaces and objects where it grows.

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 may 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 may 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 kinds of health problems may be linked to mold? What are symptoms of mold allergy?

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 nonallergic individuals, mold can irritate the eyes, skin, and airways. For example, the "black mold" 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 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.

Despite some initial concerns about other medical conditions, according to the U.S. Centers for Disease Control and Prevention (CDC), "a link between...adverse health effects, such as acute idiopathic pulmonary hemorrhage among infants, memory loss, or lethargy, and molds, including the mold Stachybotrys chartarum (Stachybotrys atra), has not been proven."

How can mold in the household be prevented?

The best way to prevent mold in the home is the control of moisture.

• Leaks in plumbing or other structures that lead to moisture buildup should be identified and repaired.



• Areas of leakage and water damage in the home should be cleaned and dried within 24-48 hours.



• Use of an air conditioner or air dehumidifier during humid seasons can help reduce the potential for moisture buildup.



• Avoid the use of carpets in humid basements and bathrooms.



• Using fans and maintaining good ventilation in the home can also help prevent or control dampness.



• Mold inhibitors can be added to household paints.



• Keep indoor humidity low (ideally between 30%-50%).



• Use bathroom fans or open bathroom windows when showering.



• Appliances that produce moisture, such as clothes dryers and stoves, should be vented to the outdoors when possible.

Is it necessary to test for mold?

According to the U.S. Environmental Protection Association (EPA), if visible mold is present, testing is usually unnecessary. There are no EPA or government standards that have been established for mold or mold spore levels, so it is impossible to prove that a building or room is in compliance with any regulations concerning mold exposure. Likewise, the CDC does not recommend routine sampling and testing of mold. Tolerable or acceptable limits of mold exposure for humans have not been defined, and since individuals vary in their susceptibility to mold, testing cannot reliably predict the degree of health risk from mold.

When mold has previously been identified and cleanup procedures have been undertaken, sampling and testing may be carried out if necessary by qualified professionals to determine that adequate cleaning has occurred.

How should mold be cleaned up and eliminated?

Mold cleanup procedures are somewhat dependent upon the extent of contamination and the type of surface that has been contaminated. Large areas of mold may require the services of a professional contractor who is skilled in mold cleanup and remediation. Hard surfaces that harbor mold may be scrubbed with detergent and water, and these should be dried completely. Porous or absorbent materials (such as cloth, ceiling tiles, carpets, etc.) may have to be discarded if they become moldy. In some cases, a dilute solution of chlorine bleach (no stronger than 1 cup of bleach in 1 gallon of water) or stronger commercial cleaners may be needed to kill the mold.

Be sure to discuss any health concerns with your health-care practitioner prior to attempting mold removal if you are sensitive to molds. When washing with soap and water, rubber gloves are recommended, but for bleach and harsher cleaning agents, nonporous gloves (for example, natural rubber, neoprene, nitrile, polyurethane, or PVC) should be worn along with protective eyewear. Wearing an N-95 respirator (available at many hardware stores) can further limit your exposure to airborne mold or spores when cleaning. Avoid touching moldy surfaces with your bare hands.

After mold removal, it is important to prevent further regrowth of mold by keeping affected areas as dry as possible.

Mold At A Glance

• Mold may live indoors or outdoors and thrives in damp, warm, and humid environments.
• Although shower stalls and basements are typical moist areas prone to the growth of molds, any moist area in the home may harbor mold.
• Allergic reactions to mold are the most common health effects of mold.
• The best way to prevent mold in the home is the control of moisture.
• There are no EPA or government standards that have been established for mold or mold spore levels, so it is impossible to prove that a building or room is in compliance with any regulations concerning mold exposure.

References:

U.S. Centers for Disease Control and Prevention, Environmental Hazards and Health Effects: Mold. http://www.cdc.gov/mold/basics.htm

U.S. Environmental Protection Association (EPA), "A Brief Guide to Mold, Moisture, and Your Home." http://www.epa.gov/mold/, 2008

Illinois Department of Public Health Fact Sheet: "Stachybotrys chartarum (atra): what you need to know." http://www.idph.state.il.us/envhealth/factsheets/stachybotrys.htm

Last Editorial Review: 3/19/2009

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