March 10, 2003 (HealthDayNews) -- Even if your home looks clean, chances are good you've got mold, often at levels high enough to trigger allergy and asthma attacks.

That bit of dour news comes courtesy of a new study that also found the mold is frequently in areas most people don't associate with it -- windowsills, for instance.

After surveying 160 homes in seven U.S. cities, Kelly A. Reynolds of the University of Arizona, Tucson, found that 100 percent of the homes tested positive for mold on some inside surface.

"On average, four sites per house were positive for mold," says Reynolds, who presents her findings March 10 at the annual meeting of the American Academy of Allergy, Asthma and Immunology in Denver.

Although 96 percent of the homeowners in the study knew mold could be a problem, she adds, only 17 percent felt their home would have a mold problem.

Then came the survey results: 88 percent of the homes had mold on window sills; 83 percent had mold on refrigerator seals (that accordion-like part), 83 percent had it under the kitchen sink and 82 had it percent in air vents.

Predictably, the bathroom was also a good breeding ground, though not as good as other areas. Almost half of the shower grouting areas and the walls above the showers showed evidence of mold.

Reynolds did not measure exact levels of the molds, but rather did a "presence-absence" test, basically getting a positive or negative result for mold but not how much was there.

Mold releases microscopic fungal spores that, if inhaled, can trigger allergy and asthma symptoms in sensitive people, Reynolds say. Mold can also worsen or cause sinus infections. High mold levels can also cause symptoms such as coughing and sniffling, which people often mistake for colds or flu, she adds.

The levels of mold needed to trigger an allergy, asthma or sinus problem vary greatly by type of mold and an individual's sensitivity, Reynolds says.

"The molds we found were all highly allergenic molds," says Reynolds, whose research was funded by an educational grant from the Clorox Co., which makes bleach.

"No standards have been set by any agency" to say at what level molds can cause health ill effects, she adds, noting "some experts say any mold you can smell or see should be eliminated."

Even though the surveyed homes were in various climates, including Dallas, New York, Atlanta, San Francisco, Tampa, Tucson and Chicago, no substantial geographic differences were found in the levels of mold, Reynolds adds.

Mold releases microscopic fungal spores that, if inhaled, can trigger allergy and asthma symptoms in sensitive people, Reynolds explains. It can also lead to sinus infections.

One piece of relatively good news from the study: Only .2 percent, or two samples, of the 1,330 taken were found to be Stachybotrys, the so-called "toxic" or "black" mold that can cause bleeding in the lungs of infants.

Another expert, Dr. Jordan S. Josephson, a New York City sinus infection expert, is not surprised by the findings.

"I know mold is pretty much ubiquitous," he says. "You can smell it in movies, locker rooms," and other dark, damp places where molds thrive.

Mold can not only aggravate asthma and allergy, but can also lead to or worsen sinus problems, adds Josephson, director of the New York Nasal and Sinus Center and an attending physician at Lenox Hill Hospital in New York City.

"Once you end up with fungal sinusitis, it lingers," he says. "Most people aren't aware that mold causes such problems."

Keeping mold at bay requires vigilance and the proper cleaning solution. Reynolds recommends cleaning areas with bleach before mold has a chance to build up.

"Follow the directions about how to dilute it," she says.

More information

To learn about mold allergy, visit the National Institute on Allergy and Immunology (www.niaid.nih.gov). For tips on eliminating mold in homes and businesses, see American Academy of Allergy, Asthma and Immunology (www.aaaai.org).

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Last Updated: March 10, 2003