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This information sheet is for people who have mold problems in their homes. It presents the health concerns associated with mold exposure and advice on finding and removing mold contamination.
Molds are fungi. Molds grow throughout the natural and built environment. Tiny particles of mold naturally occur in indoor and outdoor air. In nature, molds help break down dead materials and can be found growing on soil, foods, plant matter and other items. Molds produce microscopic cells called "spores" which are very tiny and spread easily through the air. Live spores act like seeds, forming new mold growths (colonies) when they find the right conditions.
Mold only needs a few simple things to grow and multiply: moisture, nutrients, spores and a suitable place to grow. Of these, controlling excess moisture is the key to preventing and stopping indoor mold growth.
Mold 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.
Mold can affect the health of people who are exposed to it. People are mainly exposed to mold by breathing spores or other tiny fragments. People can also be exposed through skin contact with mold contaminants (for example, by touching moldy surfaces) and by swallowing it.
The type and severity of health effects that mold may produce are usually difficult to predict. The risks can vary greatly from one location to another, over time and from person to person.
The most common health problems caused by indoor mold are allergy symptoms. Although other and more serious problems can occur, people exposed to mold commonly report problems such as: nasal and sinus congestion, coughing, wheezing/breathing difficulties, sore throat, skin and eye irritation and upper respiratory infections (including sinus inflammation).
There is wide variability in how different people are affected by indoor mold, however, the long term presence of indoor mold growth may eventually become unhealthy for anyone. The following types of people may be affected more severely and sooner than others: infants and children, elderly people, individuals with respiratory conditions or sensitivities such as allergies and asthma, persons having weakened immune systems (for example, people with HIV infection, chemotherapy patients, organ transplant recipients).
Those with special health concerns should consult a medical professional if they feel their health is affected by indoor mold.
Some types of mold can produce chemical compounds (called mycotoxins) although they do not always do so. Molds that are able to produce toxins are common. In some circumstances, the toxins produced by indoor mold may cause health problems. All indoor mold growth is potentially harmful and should be removed promptly, no matter what types of mold are present or whether it can produce some level of toxins.
First and foremost, investigate, don't test. 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.
Look for visible mold growth (may appear cottony, velvety, granular or leathery and have varied colors of white, gray, brown, black, yellow, green). Mold often appears as discoloration, staining or fuzzy growth on the surface of building materials or furnishings. When mold is visible, testing is usually not recommended or even necessary.
The Delaware Division of Public Health does not routinely recommend testing for mold. Instead, you should simply assume there is a problem whenever you see mold or smell mold odors. Testing should never take the place of visual inspection and it should never use up resources that are needed to correct moisture problems and remove all visible growth.
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. Some insurance companies and legal services may suggest sampling as a form of documentation of microbial contamination. These situations should be addressed on a case-by-case basis.
To clean up and remove indoor mold growth in small quantities, follow these steps as they apply to your home. (In all cases, refer to the New York Guidelines or the EPA handbooks: A Brief Guide To Mold, Moisture, and Your Home or Mold Remediation In Schools and Commercial Buildings prior to beginning any of the work described below.)
To keep indoor surfaces as dry as possible, try to maintain the home's relative humidity between 20-40 percent in the winter and below 60 percent the rest of the year. You can purchase devices to measure relative humidity at some home supply stores. Ventilation, air circulation near cold surfaces, dehumidification and efforts to minimize the production of moisture in the home are all very important in controlling high humidity that frequently causes mold growth in our cold climate.
Begin to dry any materials that are wet as soon as possible. For severe moisture problems, use fans and dehumidifiers and move wet items away from walls and off floors. Check with equipment rental companies or restoration firms to see if you can rent fans and dehumidifiers.
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 gypsum wallboard, insulation, plaster, carpet/carpet pad, ceiling tiles, wood products (other than solid wood) and paper products. 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.
The amount of mold particles in air can increase greatly when mold is disturbed. Consider using protective equipment when handling or working around mold contaminated materials. The following equipment can help minimize exposure to mold:
Plan and perform all work to minimize the amount of dust generated. Plan to keep all susceptible people (children, seniors, and those sensitive to indoor contaminants, including people with compromised immune systems) out of the area to help minimize their potential for exposure. The following actions can help minimize the spread of mold spores:
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. Regrowth may signal that the material should be removed or that moisture is not yet controlled.
Rebuilding and refurnishing must wait until all affected materials have dried completely. Be patient it takes time to dry out wet building materials. Be sure to continue dehumidification and watching out for telltale signs that the moisture problem might be recurring.
Some air cleaners are designed to produce ozone, which is a strong oxidizing agent and a known irritant of the lungs and respiratory system. Studies have shown that ozone, even at high concentrations, is not effective at killing airborne mold or surface mold contamination. Even if mold were killed by ozone, the health threats would not be reduced until mold contaminants are removed through cleaning. Health experts, including the Delaware Division of Public Health, do not recommend the use of ozone to address mold or any other indoor air problems.
In Delaware, you can contact The Delaware Division of Public Health, Environmental Health Evaluation Branch or visit our Inside Healthy Homes page .
Last Reviewed: July 12, 2004