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What is Mold?

Molds are simple, microscopic organisms, found virtually everywhere, indoors and outdoors. Molds can be found on plants, foods, dry leaves, and other organic material. Molds are needed for breaking down dead material. Mold spores are very tiny and lightweight, and this allows them to travel through the air. Mold growths can often be seen in the form of discoloration, ranging from white to orange and from green to brown and black. When molds are present in large quantities, they can cause allergic symptoms similar to those caused by plant pollen.

What does mold need to grow?

For mold to grow, it needs:

Can mold become a problem in my home?

Yes, if there is moisture available to allow mold to thrive and multiply. The following are sources of indoor moisture that may cause problems:

How am I exposed to indoor molds?

Mold is found everywhere, indoors and outdoors. It is common to find mold spores in the air of homes and growing on damp surfaces. Much of the mold found indoors comes from outdoor sources. Therefore, everyone is exposed to some mold on a daily basis without evident harm. Mold spores primarily cause health problems when they enter the air and are inhaled in large number. People can also be exposed to mold through skin contact and eating.

How much mold can make me sick?

It depends. For some people, a relatively small number of mold spores can cause health problems. For other people, it may take many more. The basic rule is, if you can see or smell it, take steps to eliminate the excess moisture, and to cleanup and remove the mold.

Who is at greater risk when exposed to mold?

Exposure to mold is not healthy for anyone inside buildings. It is important to quickly identify and correct any moisture sources before health problems develop. The following individuals appear to be at higher risk for adverse health effects of molds:

People with these special concerns should consult a physician if they are having health problems.

What symptoms are common?

Allergic reactions may be the most common health problem of mold exposure. Typical symptoms reported (alone or in combination) include:

Are some molds more hazardous than others?

Allergic persons vary in their sensitivities to mold, both as to amount and type needed to cause reactions. In addition, certain types of molds can produce toxins, called mycotoxins, that the mold uses to inhibit or prevent the growth of other organisms. Mycotoxins are found in both living and dead mold spores. Materials permeated with mold need to be removed, even after they are disinfected with cleaning solutions. Allergic and toxic effects can remain in dead spores. Exposure to mycotoxins may present a greater hazard than that of allergenic or irritative molds. Mycotoxins have been found in homes, agricultural settings, food, and office buildings.

How can I tell if I have mold in my house?

If you can see mold, or if there is an earthy or musty odor, you can assume you have a mold problem. Allergic individuals may experience the symptoms listed above. Look for previous water damage. Visible mold growth is found underneath materials where water has damaged surfaces, or behind walls. Look for discoloration and leaching from plaster.

What do sample results mean?

Currently there are no standards regarding acceptable levels of mold. If air sampling is performed, indoor mold concentrations should be 1/3 to 1/2 less than concurrent outdoor samples, and the types of organisms should be qualitatively similar. If indoor concentrations are elevated and/or a significant difference of organisms exist, then an indoor microbial reservoir/growth source may be present.

Is it safe to stay in my home?

Sample results can be taken to a physician for determination of individual susceptibility to specific organisms. Since no guidelines for acceptable levels of mold exist, the decision to leave the home must be made by you and your family, based on information obtained through your physician, consultant and personal research.

Can Air Duct Systems become contaminated with mold?

Yes. Air duct systems can become contaminated with mold. Duct systems can be constructed of bare sheet metal, sheet metal with an exterior fibrous glass insulation, sheet metal with an internal fibrous glass liner, or made entirely of fibrous glass. If your home's air duct system has had water damage, first identify the type of air duct construction that you have. Bare sheet metal systems, or sheet metal with exterior fibrous glass insulation, can be cleaned and disinfected. If your system has sheet metal with an internal fibrous glass liner, or is made entirely of fibrous glass, the ductwork normally will need to be removed and discarded. Ductwork in difficult locations may have to be abandoned.

Can Ozone air cleaners help remove indoor mold, or reduce odor or pollution levels?

Some air cleaners are designed to produce ozone. Ozone is a strong oxidizing agent used as a disinfectant in water and sometimes to eliminate odors. However, ozone is a known lung irritant. Symptoms associated with exposure include cough, chest pain, and eye, nose, and throat irritation. Ozone generators have been shown to generate indoor levels above the safe limit. Furthermore, it has been demonstrated that ozone is not effective in controlling molds and fungi, even at high concentrations far above safe health levels. Also, ozone may damage materials in the home. For these reasons, it is strongly recommended that you do not use an ozone air cleaner in any occupied residential space.

Water is essential for mold spores to germinate, and mold typically grows anywhere moisture levels are high. Once germinated, the spores produce visible colonies as they feed on materials such as dust, wood, sawdust, clothing and paint. The areas most prone to mold growth are associated with relatively high humidity levels, as presented below:

ATTIC If moisture is present, wood-decaying mold can grow on the underside of roof sheathing. It may not get into the building until a new roof is built, and often (if it is not disturbed) it does not pose a significant air-quality problem.

CARPET Mold can grow undetected in wet carpets, pillows and other porous materials

BATHROOM AND KITCHEN Particularly prone to mold growth, since water is used extensively in these areas. Poor cleaning can leave dust or soap film, which mold can thrive on.

AIR CONDITIONER Air conditioners can become full of mold and can spread mold spores throughout the building

EXTERIOR WALLS Large objects placed next to exterior walls reduce the temperature relative to the rest of the room, leading to higher humidity

BASEMENT The area most prone to mold growth for several reasons:

  1. Basements are generally cooler than the rest of the building, so humidity levels tend to be higher.

  2. If outside drainage spouts are clogged or broken, rain runoff can saturate the base of the building, making the foundation damp.

  3. Water from a high water table, broken or abandoned water main or cistern can rise up from the ground and soak into the foundation. This condition is known as “rising damp”