Mold Information Page

Molds are fungi. Their tiny particles are present in both indoor and outdoor air. Molds are very common in buildings and homes, and will grow anywhere there is moisture. Mold growth is encouraged by warm, humid conditions. Indoors, mold can be found where humidity levels are high, such as basements or showers. In nature, molds help break down dead materials and can be found growing on soil, foods, plant matter, and other items. No one knows how many species of fungi exist.

Molds produce microscopic cells called spores which spread easily through the air. Live spores act like seeds, forming new mold growths (colonies) when they find the right conditions. Mold may enter your home through open doorways, windows, heating, ventilation, and air conditioning systems. Spores in the air outside also attach themselves to people and animals, making clothing, shoes, bags, and pets convenient vehicles for carrying mold indoors.

Molds are microscopic fungal organisms. They grow as networks of interlocking filaments that spread on and into organic matter, leading to its decomposition. When clusters of these filaments become large enough, they are visible as fuzzy growths of mold or mildew. Bread mold is a familiar example. Unlike plants, which use energy from the sun to produce food, molds obtain their energy by digesting other organic matter.

Molds grow outdoors and, if the humidity is high enough, indoors as well. They do not have the clearly defined seasons associated with pollens, but are at their peak during months of high humidity, and are absent in outdoor air only if there is snow on the ground. They can grow on grass and on the bark of trees, and are plentiful in fallen leaves and other decaying vegetation. Indoors, they live in areas of high humidity, such as basements or poorly ventilated bathrooms.

To grow and multiply, mold requires:

• Moisture

• Nutrients

• Suitable material on which to establish itself

Of these conditions, controlling excess moisture is the key to preventing and stopping indoor mold growth.

Molds will grow in places where leakage or seepage may have occurred, such as roofs, pipes, walls, plant pots, or where there has been flooding. 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 molds. Other materials such as dust, paints, wallpaper, insulation materials, drywall, carpet, fabric, and upholstery, commonly support mold growth.

Molds come in a rainbow of colors, including red, pink, green, blue-green, brown and black. The most common molds are Cladosporium, Penicillium, Aspergillus, Alternaria, and Mucor.

Molds can be released into the air when moldy material becomes damaged or disturbed. Exposure can occur if people inhale the spores, directly handle mold materials, or accidentally ingest it.

Molds should not be permitted to grow and multiply indoors. When this happens, health problems can occur and building materials, goods, and furnishings may be damaged. For some people, a relatively small number of mold spores can cause health problems. Infants, children, immune-compromised patients, pregnant women, individuals with existing respiratory conditions (allergies, multiple chemical sensitivity, and asthma), and the elderly, are at higher risks for adverse health effects from mold.

Some types of mold are able to produce chemical compounds (called mycotoxins), although they do not always do so. In some circumstances, the toxins produced by indoor mold may cause health problems. However, all indoor mold growth is potentially harmful and should be removed promptly.

Molds must be cleaned up and sources of moisture eliminated. Wash mold off hard surfaces and dry completely. Absorbent materials, such as ceiling tiles and carpet, may have to be replaced if they are contaminated with mold. Fix leaky plumbing or other sources of water. Keep drip pans in your air conditioner, refrigerator, and dehumidifier clean and dry. Use exhaust fans or open windows in kitchens and bathrooms when showering, cooking, or using the dishwasher. Vent clothes dryers to the outside. Maintain low indoor humidity, ideally between 30-50% relative humidity. Humidity levels can be measured by hygrometers which are available at hardware stores.

Mold Madness: 10 Mold Factoids

• Potential health effects and symptoms associated with mold exposures include allergic reactions, asthma, and other respiratory complaints.

• There is no practical way to eliminate all mold and mold spores in the indoor environment; the way to control indoor mold growth is to control moisture.

• If mold is a problem in your home or school, you must clean up the mold and eliminate sources of moisture.

• Fix the source of the water problem or leak to prevent mold growth.

• Reduce indoor humidity (to 30-50%) to decrease mold growth by: venting bathrooms, dryers, and other moisture-generating sources to the outside; using air conditioners and de-humidifiers; increasing ventilation; and using exhaust fans whenever cooking, dishwashing, and cleaning.

• Clean and dry any damp or wet building materials and furnishings within 24-48 hours to prevent mold growth.

• Clean mold off hard surfaces with water and detergent, and dry completely. Absorbent materials such as ceiling tiles, that are moldy, may need to be replaced.

• Prevent condensation, and reduce the potential for condensation on cold surfaces (i.e., windows, piping, exterior walls, roof, or floors) by adding insulation.

• In areas where there is a perpetual moisture problem, do not install carpeting (i.e., by drinking fountains, by classroom sinks, or on concrete floors with leaks or frequent condensation).

• Molds can be found almost anywhere; they can grow on virtually any substance, providing moisture is present. There are molds that can grow on wood, paper, carpet, and foods.
   

Who should do mold cleanup?

Who should do the cleanup depends on a number of factors. One consideration is the size of the mold problem. If the moldy area is less than about 10 square feet (less than roughly a 3 ft. by 3 ft. patch), in most cases, you can handle the job yourself, following the guidelines below.

How do I clean up mold?

Professional cleaners or remediators may use methods not covered in this publication. Please note that mold may cause staining and cosmetic damage and it may not be possible to clean an item so that its original appearance is restored.

Tips and techniques for cleanup of mold:

• Scrub mold off hard surfaces with detergent and water, and dry completely.

• Fix plumbing leaks and other water problems as soon as possible.

• Dry all items completely. N.B. Absorbent or porous materials, such as ceiling tiles and carpet, may have to be thrown away if they become moldy. Mold can grow on or fill in the empty spaces and crevices of porous materials, so the mold may be difficult or impossible to remove completely.

• Avoid exposing yourself or others to mold (see question below: What to Wear When Cleaning Moldy Areas and Hidden Mold).

• Do not paint or caulk moldy surfaces. Clean up the mold and dry the surfaces before painting. Paint applied over moldy surfaces is likely to peel.

• Get help. If you are unsure about how to clean an item, or if the item is expensive or of sentimental value, you may wish to consult a specialist. Specialists in furniture repair, restoration, painting, art restoration and conservation, carpet and rug cleaning, water damage, and fire or water restoration are commonly listed in phone books. Be sure to ask for and check references. Look for specialists who are affiliated with professional organizations.

What do I wear when cleaning moldy areas?

It is important to take precautions to limit your exposure to mold and mold spores.  Avoid breathing in mold or mold spores. In order to limit your exposure to airborne mold, you may want to wear an N-95 respirator, available at many hardware stores and from companies that advertise on the Internet. (They cost about $12 to $25.) Some N-95 respirators resemble a paper dust mask with removable cartridges that prevent most of the mold spores from entering. In order to be effective, the respirator or mask must fit properly, so carefully follow the instructions supplied with the respirator. Please note that the Occupational Safety and Health Administration (OSHA) requires that respirators fit properly when used in an occupational setting; consult OSHA for more information (800-321-OSHA) or osha.org.  Wear long gloves that extend to the middle of the forearm. When working with water and a mild detergent, ordinary household rubber gloves may be used. If you are using a disinfectant, a biocide such as chlorine bleach, or a strong cleaning solution, you should select gloves made from natural rubber, neoprene, nitrile, polyurethane, or PVC. Avoid touching mold or moldy items with your bare hands.  Wear goggles. Goggles that do not have ventilation holes are recommended. Avoid getting mold or mold spores in your eyes.
 

How do I cleanup mold that covers an area greater than 10 square feet?

If there has been a lot of water damage, and/or mold growth covers more than 10 square feet, consult the U.S. Environmental Protection Agency (EPA) guide "Mold Remediation in Schools and Commercial Buildings." Although focused on schools and commercial buildings, this document is applicable to other building types. It is available free by calling the EPA Indoor Air Quality Information Clearinghouse at (800) 438-4318.
 

How do I cleanup mold near or in HVAC systems?

If you suspect that the heating/ventilation/air conditioning (HVAC) system may be contaminated with mold (it is part of an identified moisture problem, for instance, or there is mold near the intake to the system), consult EPA's guide "Should You Have the Air Ducts in Your Home Cleaned?" before taking further action. Do not run the HVAC system if you know or suspect that it is contaminated with mold - it could spread mold throughout the building. Visit www.epa.gov/iaq/pubs/airduct.html, or call (800) 438-4318 for a free copy.

How do I cleanup mold caused by sewage or other contaminated water?

If the water and/or mold damage was caused by sewage or other contaminated water, then call in a professional who has experience cleaning and fixing buildings damaged by contaminated water.

Do you need more information ? Visit the EPA's website.