Hidden Mold

You may suspect hidden mold if a building smells moldy, but you cannot see the source, or if you know there has been water damage and residents are reporting health problems. Mold may be hidden in places such as the back side of dry wall, wallpaper, or paneling, the top side of ceiling tiles, the underside of carpets and pads, etc. Other possible locations of hidden mold include areas inside walls around pipes (with leaking or condensing pipes), the surface of walls behind furniture (where condensation forms), inside ductwork, and in roof materials above ceiling tiles (due to roof leaks or insufficient insulation).

Investigating hidden mold problems

Investigating hidden mold problems may be difficult and will require caution when the investigation involves disturbing potential sites of mold growth. For example, removal of wallpaper can lead to a massive release of spores if there is mold growing on the underside of the paper. If you believe that you may have a hidden mold problem, consider hiring an experienced professional.

Cleanup and Biocides

Biocides are substances that can destroy living organisms. The use of a chemical or biocide that kills organisms such as mold (chlorine bleach, for example) is not recommended as a routine practice during mold cleanup. There may be instances, however, when professional judgment may indicate its use (for example, when immune-compromised individuals are present). In most cases, it is not possible or desirable to sterilize an area; a background level of mold spores will remain - these spores will not grow if the moisture problem has been resolved. If you choose to use disinfectants or biocides, always ventilate the area and exhaust the air to the outdoors. Never mix chlorine bleach solution with other cleaning solutions or detergents that contain ammonia because toxic fumes could be produced.

What to Wear When Cleaning Mold

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 a nozzle on the front, others are made primarily of plastic or rubber and have removable cartridges that trap 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 (fit testing) when used in an occupational setting; consult OSHA for more information (800-321-OSHA or www.osha.gov).
  
• Wear gloves. Long gloves that extend to the middle of the forearm are recommended. 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 (see Cleanup and Biocides). 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 Know When the Remediation or Cleanup is Finished?

You must have completely fixed the water or moisture problem before the cleanup or remediation can be considered finished.

• You should have completed mold removal. Visible mold and moldy odors should not be present. Please note that mold may cause staining and cosmetic damage.
  
• You should have revisited the site(s) shortly after cleanup and it should show no signs of water damage or mold growth.
  
• People should have been able to occupy or re-occupy the area without health complaints or physical symptoms.
  
• Ultimately, this is a judgment call; there is no easy answer. If you have concerns or questions consult our Frequently Asked Questions database and ask a question if you don't find what you need.

Mold Cleanup Guidelines

The tips and techniques presented in this section will help you clean up your mold problem. Professional cleaners or remediators may use methods not covered in this publication. Please note that mold may cause staining and cosmetic damage. It may not be possible to clean an item so that its original appearance is restored.

Fix plumbing leaks and other water problems as soon as possible. Dry all items completely.
 

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

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 discussions: 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.
 

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.

BATHROOM TIP

Places that are often or always damp can be hard to maintain completely free of mold. If there's some mold in the shower or elsewhere in the bathroom that seems to reappear, increasing ventilation (running a fan or opening a window) and cleaning more frequently will usually prevent mold from recurring, or at least keep the mold to a minimum

A Brief Guide to Mold, Moisture, and 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, follow the guidelines. However:

• If there has been a lot of water damage, and/or mold growth covers more than 10 square feet, consult EPA's Mold Remediation in Schools and Commercial Buildings. Although focused on schools and commercial buildings, this document is applicable to other building types.
  
• 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 Hygenists (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.
  
• 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.
  
• If you have health concerns, consult a health professional before starting cleanup.

Source:  Environmental Protection Agency

A Brief Guide to Mold, Moisture, and Your Home

Why is mold growing in my home?

Molds are part of the natural environment. Outdoors, molds play a part in nature by breaking down dead organic matter such as fallen leaves and dead trees, but indoors, mold growth should be avoided. Molds reproduce by means of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air. Mold may begin growing indoors when mold spores land on surfaces that are wet. There are many types of mold, and none of them will grow without water or moisture.

Can mold cause health problems?

Molds are usually not a problem indoors, unless mold spores land on a wet or damp spot and begin growing. Molds have the potential to cause health problems. Molds produce allergens (substances that can cause allergic reactions), irritants, and in some cases, potentially toxic substances (mycotoxins). Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mold are common. They can be immediate or delayed. Molds can also cause asthma attacks in people with asthma who are allergic to mold. In addition, mold exposure can irritate the eyes, skin, nose, throat, and lungs of both mold-allergic and non-allergic people. Symptoms other than the allergic and irritant types are not commonly reported as a result of inhaling mold. Research on mold and health effects is ongoing. This brochure provides a brief overview; it does not describe all potential health effects related to mold exposure. For more detailed information consult a health professional. You may also wish to consult your state or local health department.

How do I get rid of mold?

It is impossible to get rid of all mold and mold spores indoors; some mold spores will be found floating through the air and in house dust. The mold spores will not grow if moisture is not present. Indoor mold growth can and should be prevented or controlled by controlling moisture indoors. If there is mold growth in your home, you must clean up the mold and fix the water problem. If you clean up the mold, but don't fix the water problem, then, most likely, the mold problem will come back.

Source:  Environmental Protection Agency

Frequently Asked Mold Questions

What causes mold to develop?
Mold requires nutrients, water, oxygen and favorable temperatures to grow. Nutrients for mold are present in dead organic material such as wood, paper or fabrics; mold can also derive nutrients from some synthetic products such as paints and adhesives. Mold requires moisture, although some mold species can obtain that moisture from moist air when the relative humidity is above 70 per cent. Many molds thrive at normal indoor temperatures; few if any molds are able to grow below 40 F or above 100 F. Outside this range molds may remain dormant or inactive; they may begin to grow again when the temperature is more favorable. Temperatures well above 100 F will kill mold and mold spores, but the exact temperature required to kill specific species is not well established.

How does mold get into a building?
Molds are decomposers of organic material such as wood, plants and animals. Mold and mold spores are found in high concentrations wherever there is dead matter such as a pile of leaves, manure or compost. Mold spores enter buildings through the air or on people, animals and objects that are brought into the building. Spores are small bundles of genetic material and chemicals (similar to seeds) that molds make under certain conditions.

Are there harmful and non-harmful molds?
There are only a few molds that can cause infection in healthy humans. Some molds cause infections only in people with compromised immune systems. The biggest health problem from exposure to mold is allergy and asthma in susceptible people. There are more than 100,000 types of mold. Good information has been developed for only a small number of these molds – at least in terms of their effects on human health. Most people tolerate exposure to moderate levels of many different molds without any apparent adverse health effects.

Some molds produce powerful chemicals called “mycotoxins” that can produce illness in animals and people. Scientific knowledge about the health effects of these toxins on humans is quite limited.

Does mold affect everyone the same way?
No. Some individuals have a genetic makeup that puts them at risk for developing allergies to mold. People who have an allergy to mold, especially if they also have asthma, can become ill from exposure to a small amount of mold. Individuals also seem to be quite different in their response to exposure to the toxic chemicals that some molds release. These differences between individuals contribute to the difficult question of determining safe exposure limits for mold.

How much mold exposure is harmful?
No one knows the answer to this question for several reasons. Individuals are very different with respect to the amount of mold exposure they can tolerate. Children under the age of one year may be more susceptible to the effects of some molds than older individuals. Measuring or estimating “exposure” levels is very difficult. “Exposure” means the amount of mold (microscopic spores and mold fragments) that gets into a person usually by breathing, but also by eating or absorption through the skin. For example, a building may have a lot of mold in the walls but very little of that mold is getting into the air stream. In that case the people working or living in that building would have little mold exposure.

Can mold exposure cause brain damage or death?
Although some “experts” claim that individuals have brain damage or have died because of exposure to mold and especially mold toxins, there is no good science at this time to support these claims. Consequently it is prudent to minimize one’s exposure to really moldy environments. By “really moldy” we mean where there are large visible areas of mold (more than a few square feet) or the building has a “musty” odor because of hidden mold growth. There are many epidemiological studies showing that people who live in houses with dampness have many more health problems, especially respiratory, than do people who live in dry houses. This association does not “prove” that it is the mold that is responsible for the increase in illness. However, it does support the assertion that it is not wise to live in damp, moldy buildings.

Does tighter building construction promote mold development?
Tighter building construction does not by itself promote mold growth, but tight construction combined with some poor choices in design, building materials or operations can increase the probability of mold growth. What do we mean? The tighter the building construction the less air exchange there is between the inside air and the outside air. Whatever gets into the inside air stays there longer than it would in a house with loose construction. Moisture that gets into the air from activities such as cooking, bathing and even breathing will remain in a tight house longer than it would in a loose house. That’s why exhaust fans should be installed in bathrooms and kitchens and vented to the outside. Clothes dryers should also be vented to the outside.

Tight construction permits control of the air exchange between the inside and the outside and can prevent the deposition of moisture in walls and roofs. Controlling moisture, including indoor relative humidity is the key to preventing mold growth. Tight building construction when combined with source control of moisture (exhaust fans) and controlled ventilation (intentional introduction of outside air) reduces the probability of mold growth in a building. Controlled ventilation can be provided by a duct that brings outside air to the return side of the air handler of a forced air system. A timing device or fan cycler can be programmed to have the air handler turn on for a specified number of minutes each hour even when there is no call for heating or cooling. In cold climates controlled ventilation is frequently provided by a heat recovery ventilator (HRV).

Do new building materials (e.g. drywall or paper faced gypsum board) promote mold growth?
Mold needs water, a nutrient source, oxygen and favorable temperature to grow. Many species of mold love paper faced gypsum board. Why? Making paper involves the mechanical and chemical processing of wood. Paper is largely pre-digested so it is easy for mold to get nutrients from the paper. But unless there is enough moisture present mold can’t grow on the paper. If paper faced gypsum board is kept dry, it can be used and still not have mold. This material is kept dry by controlling the interior relative humidity, keeping rain from entering roofs and walls, and NOT using paper faced gypsum in areas that are likely to get wet. This means no paper faced gypsum board in shower and tub areas. Cement board, mortar or non-paper faced gypsum can safely be used in these damp areas because these products do not contain nutrients to support mold growth.

Are there reliable tests to indicate the presence of mold?
Almost all of us already have two effective mold detectors: our eyes and our noses. If black or green discoloration is noticed that is fuzzy in appearance and is in a location that is damp or had been damp, it is almost certainly mold. If a building smells musty, there probably is mold somewhere; the mold may be on boxes stored in a basement or in walls or in the crawl space. If you want to find mold, look for the presence of water or a location where water was likely to have been. If there is still any question about whether the black stuff is mold, have a reliable laboratory examine the material. All you need to know is whether mold is seen when the material is examined under the microscope.

An increasing number of companies are offering “air testing for mold.” On the surface this seems like a reasonable thing to do. The problem, however, is that the results of most air sampling for mold are meaningless for two reasons. Air sampling for mold was not developed to determine if an environment was safe or had a dangerous level of mold in the air. Air sampling was developed to help identify the location of a hidden reservoir of mold. If the source of mold is already identified, air sampling does not provide additional meaningful information. Furthermore, safe or toxic levels of air borne mold have not been established. An individual air sample for mold provides a “snapshot” of what was in the air during the few minutes of sampling. The results may not be indicative of the amount of mold that is in the air during most of the day.

Air sampling for mold should be done either to obtain an answer to a question that cannot be answered without the air sampling or to obtain data as part of a research project. The Center for Disease Control (CDC), the U.S. Environmental Protection Agency (EPA) and the American Conference of Governmental Industrial Hygienists do not recommend routine air testing for mold.

If mold is present, what’s the best way to get rid of it?
The answer depends on how much mold is present and where it is located. If the mold is on furnishings or boxes simply discard the materials. Moldy materials are not considered hazardous waste; they can be sent to a regular landfill. However, it is smart to seal the mold material in heavy plastic to protect the people who handle it in transit and prevent spreading large amounts of the mold into the building as you carry the material out of it.

If the mold is on a hard surface but occupies less than 10 square feet wash the area with soapy water (scrubbing with a brush may be necessary), rinse and allow the area to dry before repainting. If you have asthma, severe allergies and a weaken immune system get someone else to do the clean up.

Larger areas (greater than 10 square feet in area) should be cleaned by someone with experience in doing this type of work. Remember, determine what caused the moisture problem and correct that problem. Otherwise, mold is likely to recur.

Is it possible to completely eliminate mold from the inside of a home or office building?
The answer depends upon what is meant by “completely eliminate mold.” To keep a building completely free of mold spores requires very efficient air filtration and is only accomplished in special situations such as hospital operating rooms and manufacturing “clean rooms.” Remember, mold spores are in the outside air virtually all the time and some of them will get inside buildings.

However, it is possible to keep mold from growing inside a building. Moisture control is the key to controlling mold in interior spaces. Air filtration can contribute to lowering mold spores in the air but is secondary to moisture control.

Should I use bleach to get rid of mold?
No. Although bleach will kill and decolorize mold, it does not remove mold. Dead mold can still cause allergic reactions. It is not necessary to kill mold to remove mold. Soap and water and scrubbing can remove mold from hard surfaces. The Environmental Protection Agency (EPA), the Center for Disease Control (CDC) and the New York City Health Department agree that bleach or other biocides should not routinely be used to clean up mold.

How do I know when the mold clean up is finished?

The mold cleanup is finished when there is no visible mold remaining and there is no dust or dirt remaining that could contain large amounts of mold and mold spores. Routine clearance testing for mold is not necessary. Leaving a few mold spores behind is not a problem if the underlying moisture problem has been corrected. Remember that mold spores are virtually everywhere. Even if all mold and mold spores are removed as part of the cleanup, spores from outside will re-enter that space. The spores won’t be able to grow unless water is also present.

Mycotoxins

Mycotoxins are secondary metabolites produced by microfungi that are capable of causing disease and death in humans and other animals. Because of their pharmacological activity, some mycotoxins or mycotoxin derivatives have found use as antibiotics, growth promotants, and other kinds of drugs; still others have been implicated as chemical warfare agents. This review focuses on the most important ones associated with human and veterinary diseases, including aflatoxin, citrinin, ergot akaloids, fumonisins, ochratoxin A, patulin, trichothecenes, and zearalenone... read more

MOLD ALErGY

Mold and mildew are fungi. They differ from plants or animals in how they reproduce and grow. The "seeds," called spores, are spread by the wind outdoors and by air indoors. Some spores are released in dry, windy weather. Others are released with the fog or dew when humidity is high. Inhaling the spores causes allergic reactions in some people. Allergic symptoms from fungus spores are most common from July to late summer. But with fungi growing in so many places, allergic reactions can occur year round... read more

FEMA MOLD REMEDIATION FACTS

Extensive disaster-related damages may result in public facilities becoming inundated or exposed to wet and humid weather conditions for extended periods of time. The limited availability of repair and restoration contractors may delay clean-up activities. In addition, the disruption of electrical power can inhibit the use of water extraction, pumping and drying electric equipment. As such, the damaged structures and their contents may remain waterlogged until power is restored and remediation can begin. Such water saturation may cause growth and propagation of mold on structures and interior contents, causing health-related problems and increasing the cost of repairs. The following guidance is provided to assist Public Assistance staff and applicants (entities that meet the requirements of 44 CFR 206.222 - State, local governments, Indian tribes or authorized tribal organizations, and certain private non-profits) with the remediation and/or repair of their damaged facilities... read more

Killing Toxic Black Mold - How to Remove Mold Safely

Killing Toxic Black Mold - How to Remove Mold Safely - Video

How do I get rid of mold?

It is impossible to get rid of all mold and mold spores indoors; some mold spores will be found floating through the air and in house dust. The mold spores will not grow if moisture is not present... read more