Mold's mission: To eat, decompose your house
Check for places where moisture accumulates
MARY BETH BRECKENRIDGEKnight Ridder
AKRON, Ohio - What you don't see can hurt you.
Mold in buildings can compromise structures and make people sick. Sometimes that mold lurks in hidden places -- behind the walls, in the air conditioning system, on the underside of Grandma's old chest of drawers.
Yet people often ignore those sources, simply because they're not visible, said Jeffrey May, a mold-investigation specialist and author of "The Mold Survival Guide" (Johns Hopkins University Press, $18.95).
"People react most strongly to what they can see," said May, who owns May Indoor Air Investigations in Cambridge, Mass. So the slimy gunk in the shower or the black stuff in the attic may worry them, when those probably aren't nearly as threatening as what's under the basement carpet or behind the paneling.
Before you panic and start tearing out drywall, however, you should know that serious mold infestations aren't rampant.
In fact, most houses don't have a significant mold problem, said Andrew Sill, owner of Cierra Environmental, an Ohio company that specializes in mold inspection, testing and remediation.
In those that do, there's some sort of underlying cause, such as improper ventilation, a leak in a water pipe or a bathtub overflow, Sill said. "The mold follows the water," he said, "and the water doesn't just appear in the house."
Even if your house does have mold, the problem may not be significant if no one in the house is sensitive to it, said Thad Godish, a professor of natural resources and environmental management at Ball State University, who has researched mold contamination of buildings. But for people who are sensitive to it, mold can trigger asthma, chronic coughs and more serious respiratory ailments.
Mold is in the air all the time, Sill and May said, so it's impossible to achieve a level of sterility that would make a house mold-free. Nevertheless, May believes mold shouldn't be growing unchecked in any home.
So what is mold, anyway?
Mold is fungus -- actually, any of many types of fungi. Mold plays a useful role in nature, because it secretes enzymes that break down matter.
Mold becomes a problem, however, when it starts feeding on things we don't want it to, such as the wood frames of our houses or the paper that covers drywall. Mold can weaken and ultimately destroy parts of a house. It can send spores and other particles into the air we breathe.
"Mold is out there doing its job," Godish said. "It's trying to eat your house down. If you give it a chance, it will."
The most common types of fungi in a home -- what we typically refer to as mold or mildew -- belong to the genera "Cladosporium, Penicillium, Aspergillus, Alternaria, Stachybotrys and Chaetomium." Different types of mold feed on different substances, such as wood, cellulose, dust and soap scum. All need food and water to grow.
How big a problem these molds pose depends partly on how much is present. A trace of mold around the edges of windows isn't likely to release enough spores to cause health problems, Sill said, while a moldy section of basement wall could be a breeding ground of misery.
One of the most common hidden sources of mold in modern buildings is the air-conditioning system, May said. In summer, water pools in the unit and provides the perfect breeding ground for mold. In winter, when the mold is dry, particles are easily picked up and blown through the air.
Thriving in darknessBasements and crawl spaces are other places where mold tends to grow. The relative humidity typically is higher there than in the rest of the house, and Sill said the darkness allows mold to grow faster.Mold is also common in attics and bathrooms -- particularly bathrooms that don't have a fan or that stay steamy for a long time, Sill said. Houses that are left unheated can experience mold growth, too, because moisture from the air condenses on the cold walls.
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