Molds are fungi that can be found both indoors and outdoors. No one knows how many species of fungi exist but estimates range from tens of thousands to perhaps three hundred thousand or more. Molds grow best in warm, damp, humid conditions, and spread and reproduce by making spores. Mold spores can survive harsh environmental conditions, such as dry conditions, that do not support normal mold growth.

How do molds affect people?

Some people are sensitive to molds. For these people, exposure to molds can cause symptoms such as nasal stuffiness, eye irritation, wheezing or skin irritation. Severe reactions may include fever and shortness of breath. Some people with chronic lung illnesses, such as obstructive lung disease, may develop mold infections in their lungs.

In 2004 the Institute of Medicine (IOM) found there was sufficient evidence to link indoor exposure to mold with upper respiratory tract symptoms, cough and wheeze in otherwise healthy people and with asthma symptoms in people with asthma. The IOM also found limited or suggestive evidence linking indoor mold exposure and respiratory illness in otherwise healthy children. Other recent studies have suggested a potential link of early mold exposure to development of asthma in some children, particularly among children who may be genetically susceptible.

How can people decrease mold exposure?

Mold growth can be slowed by controlling humidity levels and ventilating showers and cooking areas. If there is mold growth in your home, clean up the mold and fix the water problem. Mold growth can be removed from hard surfaces with commercial products, soap and water, or a bleach solution of no more than one cup of household laundry bleach in one gallon of water.

If you choose to use bleach to clean up mold:

• Never mix bleach with ammonia or other household cleaners. Mixing bleach with ammonia or other cleaning products will produce dangerous, toxic fumes.
• Open windows and doors to provide fresh air.
• Wear non-porous gloves and protective eye wear.
• If the area to be cleaned is more than 10 square feet, consult the U.S. Environmental Protection Agency guide titled Mold Remediation in Schools and Commercial Buildings. Although focused on schools and commercial buildings, this document also applies to other building types.
• Always follow the manufacturer’s instructions when using bleach or any other cleaning product.

How to minimize mold around your home:

• Keep humidity levels as low as you can — no higher than 50% -- all day long. An air conditioner or dehumidifier will help you keep the level low. Bear in mind that humidity levels change over the course of a day, so you should check the humidity levels more than once a day.
• Use an air conditioner or a dehumidifier during humid months.
• Be sure the home has adequate ventilation, including exhaust fans.
• Add mold inhibitors to paints before application.
• Clean bathrooms with mold killing products.
• Do not carpet bathrooms and basements.
• Remove or replace previously soaked carpets and upholstery.