Mold
Mold is found virtually everywhere -- both indoors and outdoors. Everyone is exposed to some amount of mold on a daily basis without harm. However, exposure to high concentrations of indoor mold can cause health problems. This information presents the health concerns associated with mold exposure and advice on finding and removing indoor mold.
"Mold" describes a wide range of fungi found virtually everywhere indoors and outdoors. Mold can grow in and on plants, foods, dry leaves, other organic material, and in soil. In nature, molds play an important role in helping break down, or decompose, dead material. Molds produce microscopic cells called spores, which act like seeds to form new mold growths (colonies) when they find the right conditions. These spores are very lightweight and spread easily through the air. When molds grow indoors, spores become concentrated in the indoor air, and can cause health problems when they are inhaled in large numbers.
Mold only needs a few simple things to grow:
- Moisture*
- Suitable place to grow (mold prefers warm, dark, unventilated places)
- Food sources -- Outdoors this includes soil, compost, leaves, and wood. Indoors this includes drywall, wallpaper, carpet, insulation, and ceiling tiles.
*Of these, moisture is most important. Controlling excess moisture in your home is the key to preventing and stopping indoor mold growth!
Stachybotrys chartarum, or "Black Mold", (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.
Spores do not become easily airborne, so contamination of indoor air is unusual. But at higher levels, health effects such as cold-like symptoms, allergy symptoms, sinusitis, and rashes may occur. There is concern with Stachybotrys beacuse it may be associated with pulmonary hemorrhage in infants, generally those less than six months old. This is a very rare condition that results in bleeding in the lungs. However, a relationship between Stachybotrys and pulmonary hemmorage has not been proven. Further studies are needed to determine what actuallty causes acute idiopathic hemorrhage.
Not all black mold is Stachybotrys (for example, the black mold commonly found between bathroom tiles is not), but moldy homes are not healthy homes. This mold is rather uncommon in homes, and requires water-soaked cellulose (wood, paper, cotton products) to grow. Keep in mind that all mold is potentially unhealthy, so determining the type is often unnecessary.
The most common types of mold are generally not hazardous to healthy individuals. However, people who have asthma, allergies, or a weakened immune system are more likely to react to mold. Some types of mold can cause more serious health problems, but this is much more rare.
Symptoms of Mold Exposure:
Allergy symptoms are the most common health problem caused by exposure to indoor mold. Although other and more serious problems can occur, typical symptoms -- alone or in combination -- include:
- nasal and sinus congestion
- respiratory problems such as wheezing, shortness of breath, or other breathing difficulties
- cough
- sore throat
- skin and eye irritation
- eye irritation: red, watery, blurry vision, light sensitivity
- upper respiratory infection (including sinus)
- possible fever
- central nervous system problems (constant headaches, memory problems, mood changes)
There is a wide range of individual reactions in people exposed to indoor mold. For some people, a relatively small amount of any mold spores can cause health problems. Other people may only react when a large amount or certain type of spores are present. In addition, some types of mold can produce chemical compounds called mycotoxins, although they do not always do so. Molds that produce toxins are common, but only a few may cause health problems. Some types of mold can cause more serious health problems, but this is much more rare. However, it is important to remember that all noticeable indoor mold growth (toxin producing or not) is potentially harmful to health and should be promptly removed.
Long term exposure to excessive indoor mold growth may eventually become unhealthy for anyone. However, the following people may be affected more rapidly and/or more severely than others:
- infants and children
- elderly persons
- individuals with respiratory conditions or sensitivities such as asthma or allergies
- pregnant women
- persons with weakened immune systems (chemotherapy patients, organ transplants recipients, people with HIV infection, etc.)
Consult a medical health professional if you or a family member are having health problems that you believe are related to indoor mold.
If you can see it or smell it . . . Fix it!
Investigate your home! The most practical way to find a mold problem is by looking for it. Look for mold growth and use your nose to locate the source of a suspicious odor. If you see mold, or if there is an earthy or musty smell, you should assume a mold problem exists. Other clues are signs of excess moisture or the development or worsening of allergy-like symptoms. Look for:
- Visible mold growth. Mold often appears as discoloration, staining, or fuzzy growth on the surface of furnishings or building materials. It may appear cottony, velvety, granular, or leathery, and have varied colors of white, gray, brown, black, yellow, or green.
- Signs of excess moisture or water damage. Look for water leaks, standing water, water stains, warped wood, cracked plaster, or condensation problems. For example, do you see any watermarks or discoloration on walls, ceilings, carpet, woodwork, or other building materials?
- Mold growth that may be hidden behind or underneath materials such as carpet and padding, wallpaper, vinyl flooring, sink cabinets, poorly caulked showers or tubs, furniture, or stored items. Sometimes destructive techniques are needed to inspect and clean enclosed spaces where mold and moisture are hidden -- inside a wall cavity, for example.
The U.S. Environmental Protection Agency states: "Standards for airborne concentrations of mold, or mold spores, have not been set. Currently, there are no EPA regulations or standards for airborne mold contaminants." Therefore, Washtenaw County does NOT recommend testing for mold.
Although visible mold can be tested by an environmental consultant, these tests can be very expensive and are considered unnecessary by environmental health professionals. There is also no easy or inexpensive way to sample for airborne mold spores. Further, since mold occurs everywhere, ALL testing results will indicate the presence of mold. Finally, even if you were to have your home tested, it is difficult to say at what levels mold may cause health effects.
Therefore, preventative action is best: whenever you can see mold or smell mold odors, simply assume there is a problem and take measures to reduce the presence of mold in your home.
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. However:
- 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 1-800-438-4318.
- If you choose to hire a contractor (or other professional service
provider) to do the cleanup, make sure the contractor has experience
cleaning up mold. Check references and ask the contractor to follow
the recommendations in EPA's Mold
Remediation in Schools and Commercial Buildings, the guidelines of the
American Conference of Governmental Industrial Hygienists (ACGIH), or other
guidelines from professional or government organizations.
- 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. Call 1-800-438-4318 for a free copy.
- If the water and/or mold damage was caused by sewage or other
contaminated water, call in a professional who has experience cleaning and
fixing buildings damaged by contaminated water.
- If you have health concerns, consult a health professional before starting cleanup.
If you have considered the issues above and have decided to go ahead and do the clean-up work yourself, be sure to follow these guidelines:
- Identify and Fix the Moisture Problem
The most important step in solving a mold problem is to identify and correct the moisture sources that allowed mold to grow in the first place. Try to maintain the home's relative humidity between 20%-40% in the winter and less than 60% the rest of the year. Ventilation, dehumidifiers, and efforts to minimize excess moisture in the home are all important in controlling high humidity that frequently causes mold growth. Potential sources of excess indoor moisture include: -
- Flooding
- Roof leaks
- Plumbing leaks
- Humidifier use
- Line-drying laundry indoors
- Firewood stored indoors
- Condensation - caused by high indoor humidity
- Overflow or leaks from tubs, sinks, or toilets
- Inadequate venting of kitchen and bathroom humidity
- Inadequate venting of clothes dryer exhaust to outdoors
- Damp basement or crawl space
- House plants - over-watering them can generate large amounts of
moisture
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Begin Drying All Wet Materials
As soon as possible, begin drying any damp materials. If necessary, use fans and dehumidifiers. Move wet items away from walls and off floors. Ventilate the area thoroughly. Ideally, expose the affected area to plenty of sunlight.
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Remove and Dispose of Mold Contaminated Materials
Wet or damp porous materials that have mold growing on them, or that smell moldy, need to removed. Such materials may include drywall, insulation, plaster, carpet and pad, ceiling tiles, wood products (other than solid wood), and paper products. These materials should be bagged and thrown away. Non-porous materials with surface mold growth can be saved if they are cleaned well and kept dry. -
Take Steps to Protect Yourself:
The amount of mold spores in the air can greatly increase when mold is disturbed. Consider using protective equipment when handling or working around materials contaminated with mold. The following equipment and precautionary measures can help minimize exposure to mold during clean-up:- Rubber gloves
- Eye goggles
- Protective clothing that can be easily cleaned or discarded
- Consider wearing a mask or respirator to protect against breathing airborne spores. They can be purchased from hardware stores; select one for particle removal (sometimes referred to as an N-95).
- Enclose all moldy materials in plastic before carrying through the home
- Damp clean the entire work area to pick up any mold spores in settled dust
- Ask others to leave the areas being cleaned
- Ventilate your home both during and after the clean up
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Clean Surfaces
Surface mold growing on non-porous materials such as plastic, glass, metal, and solid wood can usually be cleaned. -
- Thoroughly scrub the contaminated surfaces using a stiff brush or cleaning pad, hot water, and a non-ammonia soap/detergent or commercial cleaner.
- Collect excess cleaning liquid with a sponge, mop, or wet/dry vacuum.
- Rinse entire area with clean water.
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Disinfect Surfaces
After cleaning has removed all visible mold, disinfect the area to kill any mold missed by the cleaning. -
- Mix 1/2 to 1 cup of bleach per gallon of water and apply to surfaces where mold had been growing.
- Collect excess bleach solution with a sponge, mop, or wet/dry vacuum. DO NOT rinse or wipe dry -- allow the areas to air dry.
CAUTION: Never mix bleach with ammonia or other cleaning products -- the fumes are toxic!
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Remain on Mold Alert
Continue looking for signs of moisture problems or return of mold growth, particularly in areas of past growth. If mold returns, repeat cleaning steps and consider using a stronger solution to disinfect the area again. Re-growth may signal that the material should be removed or that excess moisture is not yet controlled.
Mold Prevention Tips
- Fix leaky plumbing and leaks in the building envelope, such as the roof, as soon as possible.
- Watch for condensation and wet spots. Fix source(s) of moisture problem(s) as soon as possible.
- Prevent moisture due to condensation by increasing surface temperature or reducing the moisture level in air (humidity). To increase surface temperature, insulate or increase air circulation. To reduce the moisture level in air, repair leaks, increase ventilation (if outside air is cold and dry), or dehumidify (if outdoor air is warm and humid).
- Keep heating, ventilation, and air conditioning (HVAC) drip pans clean, flowing properly, and unobstructed.
- Vent moisture-generating appliances, such as dryers, to the outside where possible.
- Install and use exhaust fans in bathrooms where possible.
- Maintain low indoor humidity, below 60% relative humidity (RH), ideally 30-50%, if possible.
- Perform regular building/HVAC inspections and maintenance as scheduled.
- Clean and dry wet or damp spots within 48 hours.
- Don't let foundations stay wet. Provide drainage and slope the ground away from the foundation.
For More Information:
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Washtenaw County Planning & Environment: (734) 222-3800
page updated 2/20/07
on July 6, 2008 6:32 pm