Frequently Asked Questions

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How common is mold in buildings?

Molds are very common in buildings and homes. Mold will grow in places with a lot of moisture, such as around leaks in roofs, windows, or pipes, or where there has been flooding. Mold grows well on paper products, cardboard, ceiling tiles, and wood products. Mold can also grow in dust, paints, wallpaper, insulation, drywall, carpet, fabric, and upholstery.
The most common indoor molds are Cladosporium, Penicillium, and Aspergillus.  We do not have precise information about how often different molds are found in buildings and homes.

How do molds affect people?

Exposure to damp and moldy environments may cause a variety of health effects.  Some people are sensitive to molds. For these people, exposure to molds can lead to symptoms such as a stuffy nose, wheezing, red or itchy eyes, or skin. Some people, such as those with allergies to molds or with asthma, may have more intense reactions. Severe reactions may occur among workers exposed to large amounts of molds in occupational settings, such as farmers working around moldy hay. Severe reactions may include fever and shortness of breath.

How do molds get in the indoor environment and how do they grow?

Mold is found both indoors and outdoors. Mold can enter your home through open doorways, windows, vents, and heating and air conditioning systems. Mold in the air outside can also attach itself to clothing, shoes, and pets can and be carried indoors. When mold spores drop on places where there is excessive moisture, such as where leakage may have occurred in roofs, pipes, walls, plant pots, or where there has been flooding, they will grow. Many building materials provide suitable nutrients that encourage mold to grow. Wet cellulose materials, including paper and paper products, cardboard, ceiling tiles, wood, and wood products, are particularly conducive for the growth of some molds. Other materials such as dust, paints, wallpaper, insulation materials, drywall, carpet, fabric, and upholstery, commonly support mold growth.