Mold, Mildew and Fungi from Flooding
- A Brief Guide to Mold, Moisture, and Your Home - Environmental Protection Agency
- Mold and Your Health - Centers for Disease Control & Prevention
Frequently Asked Questions
Following a widespread flooding disaster, many questions arise from citizens within the communities affected and from the many volunteers and organizations that are working in the devastated area. Personal health and safety is a priority for everyone. The following information is aimed at preventing both disease and injury by answering many common concerns and providing valuable preventive health tips.
What are molds?
Molds are simple, microscopic organisms that are present virtually everywhere, indoors and outdoors. Molds, along with mildew, mushrooms, and yeasts are fungi. There are more than 100,000 species of mold that produce tiny, lightweight spores which drift through the indoor and outdoor air. Live spores act like seeds, forming new mold growths (colonies) when they find the right conditions.
How does mold grow?
Mold can grow almost anywhere there is water, high humidity or dampness. When mold spores land on a damp spot they begin growing and digesting whatever they are growing on in order to survive. This digestion process, if unchecked will eventually damage and then destroy the organic material the mold is feeding on. The way to control indoor mold growth is to control moisture. Removing the source of moisture - through repairs or dehumidification - is critical to preventing mold growth.
How am I exposed to indoor molds?
Exposure to mold occurs primarily when there is active mold growth within the home, office or school where people live or work. Everyone is exposed to some mold on a daily basis without evident harm. It is common to find mold spores in the air inside homes, and most of the airborne spores found indoors come from outdoor sources. When moldy material becomes damaged or disturbed, spores can be released into the air. People can also be exposed to mold by touching contaminated materials and by eating contaminated foods.
How can mold affect your health?
Most types of mold that are routinely encountered are not hazardous to healthy individuals. Mold spores primarily cause health problems when people inhale large quantities of spores. Reactions are dependent on a person's individual susceptibility. People living or working in buildings with wet carpet, walls, mattresses and/or furniture can have health problems such as allergies, asthma and sneezing. The most common health problems caused by indoor mold are allergy symptoms. However, the long-term presence of indoor mold growth may eventually become unhealthy for anyone.
Depending on the amount of exposure and a person's individual vulnerability, more serious health effects - such as fevers and breathing problems - can occur but are unusual. Persons at highest risk are asthmatics, people with allergies, infants and children, elderly, pregnant women, people with existing respiratory diseases, and people with compromised immune systems. Those with special health concerns should consult a medical professional if they feel their health is affected by indoor mold.
What should I do if I suspect my health or my child's health is
If you believe that you or your child have symptoms that you suspect are caused by exposure to mold, you should see a physician. Keep in mind that many symptoms associated with mold exposure may also be caused by many other illnesses. You should tell your physician about your symptoms and when, how and for how long you think you or your children were exposed to mold.
How can I tell if I have mold in my house?
The most practical way to find a mold problem is by using your eyes to look for mold growth and by using 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 worsening of allergy-like symptoms. Evidence of past or ongoing water damage should also trigger more thorough inspection. You may find mold growth underneath water-damaged surfaces or behind walls, floors or ceilings.
- Look for visible mold growth (may appear cottony, velvety, granular or leathery and have varied colors of white, gray, brown, black, yellow or green). Mold often appears as discoloration, staining or fuzzy growth on the surface of building materials or furnishings. When mold is visible, testing is not recommended.
- Search areas with noticeable mold odors.
- Look for signs of excess moisture or water damage. Look for water leaks, standing water, water stains and condensation problems. For example, do you see any watermarks or discoloration on walls, ceilings, carpet, woodwork or other building materials?
- Search behind and underneath materials (carpet and pad, wallpaper, vinyl flooring, sink cabinets), furniture, or stored items (especially things placed near outside walls or on cold floors). Sometimes destructive techniques may be needed to inspect and clean enclosed spaces where mold and moisture are hidden; for example, opening up a wall cavity.
Should I be concerned about mold in my home?
Yes. If indoor mold contamination is extensive, it can cause very high and persistent airborne spore exposures. Persons exposed to high spore levels can become sensitized and develop allergies to the mold or other health problems. Mold growth can damage your furnishings, such as carpets, sofas and cabinets. Clothes and shoes in damp closets can become soiled. In time, unchecked mold growth can cause serious damage to the structural elements in your home. If you can see or smell mold inside your home, take steps to identify and eliminate the excess moisture and to cleanup and remove the mold.
How can I prevent indoor mold problems in my home?
Inspect your home regularly for the indications and sources of indoor moisture and mold. Take steps to eliminate sources of water as quickly as possible.
- Stop the source of leak or flooding.
- Remove excess water with mops or wet vacuum.
- Whenever possible, move wet items to a dry and well ventilated area or outside to expedite drying. Move rugs and pull up areas of wet carpet as soon as possible.
- Open closet and cabinet doors and move furniture away from walls to increase circulation.
- Run portable fans to increase air circulation. Do NOT use the home's central blower if flooding has occurred in it or in any of the ducts.
- Run dehumidifiers and window air conditioners to lower humidity.
- Do NOT turn up the heat or use heaters in confined areas, as higher temperatures increase the rate of mold growth.
- If water has soaked inside the walls, it may be necessary to open wall cavities, remove baseboards, and/or pry open wall paneling.
- Spraying with a household disinfectant on fungi and mold will not remove the organisms and can exacerbate breathing problems.
- Keep indoor surfaces as dry as possible. Try to maintain the home's relative humidity between 20-40 percent in the winter and less than 60 percent the rest of the year.
- Provide adequate ventilation, air circulation near cold surfaces, dehumidification or other methods to minimize the production of moisture in the home and control high humidity that frequently causes mold growth in our cold climate.
Should I test for mold?
Mold testing can be expensive and time consuming, and it usually requires special equipment and trained technicians to obtain reliable results. But most importantly, you probably will not get the results from your mold test for a couple of weeks, during which time the mold problems could become significantly worse.
If I decide to test, what should happen?
If you have your home tested, a trained technician with special equipment will take an outdoor air sample at the same time as an indoor sample. This will allow the technician to determine whether the number of spores inside your home is significantly higher than the number outside your home. A higher indoor level could mean that mold is growing indoors. Once you determine the level of mold in a home, there are no standards for judging if the level could cause problems for the occupants or when a house is clean.
However, sometimes mold growth is hidden and difficult to locate. In such cases, a combination of air (outdoor and indoor air samples) and bulk (material) samples may help determine the extent of contamination and where cleaning is needed. However, mold testing is rarely useful for trying to answer questions about health concerns.
How should mold be cleaned?
The most effective way to treat mold is to correct underlying water damage and clean the affected area. Mold should be cleaned as soon as it appears. Persons cleaning mold should be free of symptoms and allergies and should wear gloves during the cleaning process. Small areas of mold should be cleaned using a detergent/soapy solution or an appropriate household cleaner. The cleaned area should then be thoroughly dried. Dispose of any sponges or rags used to clean mold.
If the mold returns quickly or spreads, it may indicate an underlying problem such as a leak which must be fixed to successfully eliminate mold problems. If mold contamination is extensive, a professional abatement company may need to be consulted.
Follow these steps to clean mold:
- Begin drying all wet materials. As soon as possible, begin drying any materials that are wet. For severe moisture problems, use fans and dehumidifiers and move wet items away from walls and off of floors. Check with equipment rental companies or restoration firms to rent fans and dehumidifiers.
- Remove and dispose of mold contaminated materials. Items which have absorbed moisture (porous materials) and which have mold growing on them need to be removed, bagged and thrown out. Such materials may include sheet rock, insulation, plaster, carpet, carpet pad, ceiling tiles, wood products (other than solid wood) and paper products. If there was flooding, sheetrock should be removed to a level above the high-water mark. Visually inspect the wall interior and remove any mold-contaminated materials. Likewise, any such porous materials that have contacted sewage should also be bagged and thrown away. Non-porous materials with surface mold growth may be saved if they are cleaned well and kept dry
- Remove moldy items as soon as possible. Spores are more easily released when moldy materials dry out.
Clean surfaces. Surface mold growing on non-porous materials
such as hard plastic, concrete, glass, metal, and solid wood can
usually be cleaned.
- Thoroughly scrub all contaminated surfaces using a stiff brush, hot water and a non-ammonia soap/detergent or commercial cleaner.
- Use a stiff brush or cleaning pad on cement-block walls or other uneven surfaces.
- Collect excess cleaning liquid with a wet/dry vacuum, mop or sponge.
- Rinse area with clean water and collect excess rinse water.
- Wash all clothing items in hot soapy water.
- Dry all cleaned items thoroughly or mold will return.
- Solid materials - glass, plastic, and metal - can generally be kept after they are thoroughly cleaned.
Disinfect Surfaces (if desired). After cleaning has removed
all visible mold and other soiling from contaminated surfaces, a
disinfectant may be used to kill mold that may have been missed by
the cleaning. In the case of sewage contamination, disinfection must
- Mix 1/4 cup bleach per gallon of water and apply to surfaces where mold growth was visible before cleaning. The solution can be applied with a spray bottle or garden sprayer, be sponged on or applied by other methods. Using bleach straight from the bottle is actually LESS effective than diluted bleach.
- Allow the bleach solution to dry on the surface, typically 10 minutes is recommended for a bleach solution.
- If you use another commercially available disinfectant follow the label instructions. Keep the disinfectant on the treated material for the prescribed time before rinsing or drying.
- Collect any run-off of bleach solution with a wet/ dry vacuum, sponge or mop.
- Disinfectants are intended to be applied to thoroughly cleaned materials and are used to ensure that most microorganisms have been killed. Therefore, do not use disinfectants instead of, or before, cleaning materials with soap or detergent.
- Allow all disinfected items to dry thoroughly or mold will return.
- Always handle bleach with caution. Never mix bleach with ammonia - toxic chlorine gas may result. Bleach can irritate the eyes, nose, throat, and skin. Provide fresh air (for example, open a window or door). Protect skin and eyes from contact with bleach. Test solution on a small area before treatment, since bleach is very corrosive and may damage some materials.
- Remain on MOLD ALERT. Continue looking for signs of moisture problems or return of mold growth. Be particularly alert to moisture 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 moisture is not yet controlled.
Can air ducts become contaminated with mold?
Air duct systems can become contaminated with mold. Duct systems may be constructed of bare sheet metal, sheet metal with fibrous glass insulation on the exterior, or sheet metal with an internal fibrous glass liner, or they may be made entirely of fibrous glass. Bare sheet metal systems and sheet metal with exterior fibrous glass insulation can be cleaned and disinfected. Ductwork made of sheet metal with an internal fibrous glass liner or made entirely of fibrous glass if water damaged, will often need to be removed and discarded. Ductwork in difficult-to-reach locations may have to be abandoned. If you have other questions, contact an air duct cleaning professional or licensed contractor.
When can we rebuild?
Rebuilding and refurnishing must wait until all affected materials have dried completely. Be patient it takes time to dry out wet building materials.
How do you know when you have finished remediation/clean-up?
- You must have completely fixed the water or moisture problem.
- Mold should be completely removed. Visible mold, mold-damaged materials, and moldy odors should not be present.
- If you have sampled for mold, the kinds and concentrations of mold and mold spores in the building should be similar to those found outside, once clean-up activities have been completed.
- You should re-inspect the site shortly after remediation, and it should show no new signs of water damage or mold growth.
- You should be able to continue to occupy the space without experiencing health complaints or physical symptoms.