Toxic Mold and Moisture

Toxic black mold needs a source of nourishment and a source of water in order to thrive. Toxic mold can grow on — and eat — almost any organic surface and may grow on inorganic surfaces if a food source is nearby. But toxic mold colonies can only thrive where there is adequate moisture. Controlling moisture in your home environment is the surest way to eliminate toxic mold and prevent new mold growth.

Humidity and Mold

Any indoor area where the relative humidity is at or above 55 percent presents the potential for toxic mold growth. Bathrooms and kitchens, where water is often in use, are likely to be the most humid rooms in any home. Basements and crawl spaces might also have high humidity levels. Rooms with houseplants or water features, such as aquariums or fountains, may exceed the 55 percent relative indoor humidity level that encourages mold growth.

Detecting and Monitoring Humidity

Humidity sensors, also called moisture meters, are available in many hardware stores for less than $20. These meters provide a continual digital readout of the amount of moisture in the air. Experts suggest you monitor humidity levels in:

• Every kitchen and bathroom, especially near sinks and toilets
• The attic, especially between the roof and the ceiling
• Inside wall cavities, especially if there has ever been water damage
• The basement and any crawl spaces
• Inside closets, pantries, and cabinets
• Inside heating/air conditioning ductwork, especially near the filter

Toxic Mold and Ventilation

Mold grows best in areas where moisture becomes trapped, such as behind wallpaper, or between a piece of furniture and a damp wall. The solution to controlling indoor mold is to provide ventilation that keeps air moving and gives humidity a chance to evaporate. Every living space must have a means to take in and release air; storage spaces can be vented or modified to allow air circulation and prevent moisture buildup.

Experts suggest you control indoor humidity by:

• Adjusting ventilation so the intake is slightly higher than the exhaust, creating a slightly higher level of air pressure inside than outdoors.
• Providing ventilation to outside for appliances such as clothes dryers and range hoods. Every combustion appliances, including stoves, fireplaces, and furnaces, create some moisture.
• Maintaining duct work and ventilation systems, sealing cracks and keeping doors tight-fitting, and fans fully operational.
• Store firewood outside the living space.

Toxic Mold and Dehumidifiers

In areas where the relativity humidity cannot be brought down below 55 percent by ventilation alone, dehumidifiers can help. These appliances use fans to pull moisture from the air, then condense and store the water in sealed tanks, which you can carry outside the house for disposal. Dehumidifiers come in a range of sizes. Experts say several small units at various locations in the home are more effective than one central unit. Basement and bathroom dehumidifiers are often most effective.

Air conditioners serve as a sort of dehumidifier by condensing water and shuttling it outside. Running a window air conditioning unit can help lower indoor relative humidity. Be sure the air conditioning unit is properly vented so water drains outside and away from the house.

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