Once it takes root, mold can spread throughout a structure. Here mold has spread behind a wall, meaning the wall will likely have to be replaced.

The symptoms can be as minor as a headache and occasional difficulty breathing or as severe as memory loss, scarring of the lung tissue, even death. The culprit is mold.

Mold is one of the major causes of poor indoor air quality (IAQ) in homes, schools and offices. According to a 1999 study by the Mayo Clinic, nearly 37 million Americans suffer from chronic sinus infections that can be traced directly to molds and other IAQ problems.

Mold occurs naturally in the environment, both indoors and outdoors. Tiny mold spores are traveling through the air at all times. As long as good ventilation is maintained in indoor environments, mold usually isn't a problem. The problem starts when mold spores land indoors on damp surfaces. Then the mold feeds off the surface, creating more spores. Places where water collects, or can leak, such as ceiling tiles, behind shower walls, plasterboard or inside hvac systems, are especially prone to mold growth. If left untreated, a mold can take hold in as little as 24 hours, affecting the health of many of the people who come in contact with it.

While many molds are fairly innocuous, others can be harmful, even deadly. The Stachybotrys mold, along with Memnoniella and Aspergillus versicolor, belong to a family of molds that produce mycotoxins, airborne pollutants than can cause loss of hearing, memory, dizziness and in rare cases can be fatal. In 1999, USA Weekend magazine profiled the case of a family driven from their luxurious Texas home by the Stachybotrys mold.

When a mold takes root, the only way it can be permanently eradicated is by controlling the moisture that the mold is feeding on. Drying the water-damaged items and areas is a must and porous and absorbent materials such as tile or carpet may have to be replaced. To keep mold from reoccurring, humidity must be controlled and ideally kept between 30-60%.

Problem is growing

Mold and IAQ-related health problems appear to be on the rise. A 1994 study of 10,000 homes in North America by the Harvard University School of Public Health said that half had water damage and mold problems, increasing the likelihood that the occupants would suffer respiratory difficulties.

Experts say the energy-conscious building trend that took hold in the 1970s is partly to blame. Airtight construction may help hvac systems operate more efficiently, but it can also mean that they circulate old, contaminated air. Building materials may also play a part, since insulation can trap moisture behind walls and some construction materials are ideal for mold growth.

Schools have been hit especially hard by mold and other IAQ problems. A U.S. government study published last year in IAQ Applications, a journal of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, said more than 8 million children have problems which can be traced to poor IAQ. Bad air can cause children to become drowsy, lose concentration or suffer chronic headaches. The U.S. government's General Accounting Office (GAO) says one in five American schools have IAQ problems, with many of the schools found in poorer school districts. This may play a role in the rise of asthma among children, which has shot up 49% since 1982.

Dealing with IAQ in a school setting is difficult because by design, most schools are densely populated. To make the most use of space, machines that might affect IAQ, such as copiers, are often placed without any thought as to exhaust or fumes. In many buildings studied, teachers without an understanding of IAQ overused air fresheners in classrooms. And maintenance personnel often would paint or clean during hours when school was in session, further affecting air quality. In buildings with desiccant systems, none of the maintenance staffs surveyed understood that the systems were designed to operate continuously, so they were often turned off on less humid days.

Recognizing the need for an easy and economical way for homeowners and building maintenance personnel to check for mold and IAQ problems, Air Quality Sciences Inc. (AQS), of Atlanta has developed test kits. The Mold and Allergen Test Kit checks for a variety of environmental molds as well as dust mites, cat, dog and cockroach allergens. The IAQ kit tests for formaldehyde, ordorants, volatile organic compounds and surface molds.

"You don't have to be an IAQ person to perform these tests," said Todd Lowenthal, IAQ product manager for Air Quality Sciences. "These tests are very user-friendly."

After samples are collected, AQS takes the test data and supplies building officials with a report on the environmental health of the structure. The kits have proven especially popular with school officials, Lowenthal said. For larger buildings or corporations, AQS also performs professional on-site analysis.

'Mold is gold'

The increasing awareness by the public and health officials on the dangers of mold has been a windfall for some hvac companies who are now expanding their services to include mold remediation. One such company is Video-Aire/Enviro-Mold IAQ Services of Fort Worth, Texas. Company owner Bob Allen expanded his 10-year-old hvac duct cleaning business to partner with experts in the field of mold removal. Using equipment first developed for his video-assisted duct cleaning service, Allen now cleans air ducts and registers of Stachybotrys, Cladosporium and other problem fungi.

Allen believes the mold remediation business is where duct cleaning was more than a decade ago - ready to explode. "Mold is gold," he said. "It's huge. It's an area that's just waiting to happen." It's profitable, too - Video-Aire/Enviro-Mold charges anywhere from $2,000 to $150,000 for its remediation service.

However, he added that many newcomers to the field he sees are not performing the service properly. "You have to go in and set up negative pressure, containment systems," Allen said. And because some substances are potentially lethal, workers have to respirators and body suits to protect themselves.

And while it only takes a day or so for the mold to be removed, that isn't the end of the ordeal for many building occupants and homeowners. Often walls, ceilings and other places where the mold has penetrated may have to be replaced before occupants can return to their homes or offices.

"We've got people who have been out for months," Allen said. "It can get out of hand quick."