Monday, April 11, 2011

Cleaning Up a Mold Problem


If the routine inspection of your home identifies a mold problem you need to address it immediately. Mold will ultimately destroy the materials it grows on because it grows by consuming the organic matter. A small leak and small area of mold impact is fairly straightforward to deal with. Ignoring it will not make it go away, but allow it to flourish and expand. Signs of mold are discolored patches or cottony or speckled growth on walls or furniture or an earthy or musty smell or odor. People who suffer from mold-allergies will experience hay fever like symptoms all year long when in the house. Any water damaged areas should be carefully inspected for mold. Mold growth is often found underneath water-damaged surfaces (for example, wallpaper and carpeting) or behind walls, floors, or ceilings. If you smell something musty in your home, do not grab the air freshener; find the source of the smell. Look for moisture and water stains; feel for damp carpeting especially in basements feel for damp or soft wall board. If you find these you will probably find the mold beneath or behind it.

Now that you have found the mold problem, the next step is to locate the source of water and/or moisture and stop it. A mold problem can not be solved or even begun to be solved until the underlying moisture problem, water seepage, or leak is fixed. Many leaks only occur during rain and can be difficult to locate and easy to ignore. Certainly, dry out the interior materials carefully to prevent the growth of mold, but this is not a substitute for repairing the underlying source of the leak and verifying that the leak has been stopped.

The US EPA, the US Center for Disease Control and Prevention (CDC) and most state Departments of Health all define a small mold problem as one that involves an area of less than 10 square feet. Everyone agrees that homeowner or maintenance person using personal protective equipment and proper procedures can remediate a mold problem that size. Large problems involving areas greater than 100 square feet probably require an experienced, professional contractor who has been trained in mold remediation and is following the guidelines developed and approved for commercials spaces and schools. Many of the building materials remediation techniques were developed to remediate hazards in schools (for example lead based paint, asbestos and mold). For in-between cases, the type of containment and personal protection will be a matter of judgment.

For remediating a small mold problem, basic personal protective equipment consists of eye protection, skin protection, and at a minimum an N-95 respirator. This type of respirator covers the nose and mouth and will filter out 95% of particulates in the air. It is available in most hardware stores. It looks similar to the fibrous masks used for dust so do not confuse them. Gloves are necessary to protect the skin from coming in contact with mold allergens or toxins and from cleaning solutions. Long gloves that extend to the middle of the forearm are best. Gloves made from natural rubber, neoprene, nitrile, polyurethane, or PVC should be used. (Do not touch your skin, face or cell phone with a gloved hand.) To protect your eyes, use properly fitted goggles without ventilation holes. Goggles must be designed to prevent the entry of dust and small particles. Wear a long sleeve shirt and long pants that can be thrown away or disposable paper overalls.

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), do not run the HVAC system this could spread mold throughout the building. Duct systems may be constructed of bare sheet metal, sheet metal with fiberglass insulation on the outside, sheet metal with fiberglass on the inside, or entirely of a flexible fiberglass tube. Bare sheet metal systems and sheet metal with exterior insulation can be cleaned and disinfected. However water damaged fiberglass interior insulating or tubing will have to be removed and disposed of. Note that no chemical biocides are currently registered by EPA for use in internally-insulated or fiber air duct systems.

The first step in mold remediation is to isolate the area so that mold spores will not be spread and remove of the mold. Porous materials can sometimes be saved. Wet vacuum (in the case of porous materials, some mold spores/fragments will remain in the material but will not grow if the material is completely dried). Steam cleaning may be an alternative for carpets and some upholstered furniture. However it is important to understand that mold sensitized or allergic individuals can be impacted by dead mold spores so that disposal of porous materials may be necessary. Mold impacted insulation, wallboard, carpet padding, probably carpet and furniture should be disposed of.

Clean non porous surfaces with a water and detergent solution (except finished wood surfaces where you should use wood cleaner). For nonporous smooth materials damp wiping with water or a detergent may be all that is necessary. Uneven surfaces may require a stiff brush or cleaning pad. To remove mold spores from dried material (like books and papers) a high-efficiency particulate air (HEPA) vacuum is used. There are special archival techniques for books and libraries; ultimately many mold impacted porous materials will have to be discarded. Mold impacted insulation, wall paper, wall to wall carpeting and padding, wallboard should be disposed of.

Once the impacted area has been cleaned of mold, rinse cleaned items with water and dry thoroughly. After cleaning, the area should be disinfected. Chlorine bleach is the most common disinfectant, but obviously cannot be used on carpeting, fabric and finished surfaces. Depending on what regulatory source you go to either a 10% (1 ½ cups of bleach per gallon of water) solution of household bleach or a 1/16th (one cup bleach per gallon of water) is recommended as a disinfectant. Do not use disinfectants instead of, or before, cleaning nonporous materials with soap or detergent. Do not use too much bleach. Bleach straight from the bottle is actually less effective than diluted bleach in killing molds. The bleach solution requires time to work, typically, 10 minutes is recommended before rinsing the bleach off. Once more rinse disinfected items with water and dry thoroughly.

If the remediation job disturbs mold and mold spores become airborne, then the risk of respiratory exposure and impact increases. Actions that are likely to stir up mold include: breakup of moldy porous materials such as wallboard; invasive procedures used to examine or remediate mold growth in a wall cavity; actively stripping or peeling wallpaper to remove it; and using fans to dry items. When there are large areas to remediate or the potential to release large quantities of mold spores or toxins to other areas of the home, then a professional mold remediation firm should be used.

Check references and verify that the contractor and all employees wear appropriate protective clothing, have been adequately trained and follow the recommendations in EPA’s Mold Remediation in Schools and Commercial Buildings, the guidelines of the American Conference of Governmental Industrial Hygenists (ACGIH), or other guidelines from the state Department of Health. Verify that the contactor carries liability insurance addressing mold and appropriate workman’s compensation insurance. A quick way to judge the professionalism and training of a mold remediation specialist is to check out their respirators and protective clothing. A professional firm should be using in areas of limited exposure a half-face or full-face air purifying respirator (APR) equipped with a HEPA filter cartridge. These respirators contain both inhalation and exhalation valves that filter the air and ensure that it is free of mold particles. Note that APRs need to be properly fitted to get a good seal on the face (workers must be clean shaven to achieve this so look at the workers).

If the mold problem is extensive and workers will be exposed for an extended period of time and/or involves large amounts of porous materials where high levels of airborne dust or mold spores are likely, a full-face, powered air purifying respirator (PAPR) is recommended by the regulators. Full-face PAPRs use a blower to force air through a HEPA filter. The HEPA-filtered air is supplied to a mask that covers the entire face or a hood that covers the entire head. The positive pressure within the hood prevents unfiltered air from entering through penetrations or gaps. Individuals must be trained to use their respirators before they begin remediation. In addition, the firm should use full containment of the area. Full containment typically consists of double layers of polyethylene used to create a barrier between the moldy area and other parts of the home or building. A decontamination chamber or airlock should be constructed for entry into and exit from the remediation area. The entryways to the airlock from the outside and from the airlock to the main containment area should consist of a slit entry with covering flaps on the outside of entry. If the contractor does not have this equipment and take these steps then find a contractor who does.

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