You've heard of Radon, asbestos and lead paint. Now meet the newest official pollutant - mold. Mold is a biological pollutant, a fungi that grows in moist conditions. Molds are found in up to 50 percent of all structures, according to the Environmental Protection Agency (EPA.) And it could kill your next real estate deal.

Milton, Ontario Realtor Chris Newell recently lost a sale because of indoor mold. "The seller had a pre-sale inspection done, and it revealed minor cosmetic problems," says Newell. "My buyers brought in a 'good' inspector, and he discovered that the entire underside of the roof was covered in black mold."

Mold is considered a serious health hazard, and the problem now has the attention of the EPA, The U.S. Consumer Product Safety Commission, and the American Lung Association, among other groups. Each has contributed research and information to a new EPA Web page devoted exclusively to molds and its dangers.

Among recent findings:

• Lung disease is the fastest growing cause of death in the U.S., and ranks as the nation's third largest killer, and it's not all due to tobacco smoke. Molds and other biological pollutants affect air quality and contribute to respiratory diseases, says the ALA.
• One third to one half of all structures have damp conditions that may encourage development of pollutants such as molds and bacteria, which can cause allergic reactions and asthma and spread infectious diseases, says the EPA.
• People spend about 90 percent of their time indoors, says the CPSC, raising their exposure to biological pollutants to dangerous levels.

While there is no proven relationship with the aging population of North American homes and the development of molds, many older homes, particularly those built with wood, may have structural and maintenance issues that could contribute to the problem. "Our mission is to prevent death and injury from products," explains Ken Giles, spokesperson for the CPSC. "While we try to set standards for products of the future, we recognize that many homes are older and that people have older products in their homes, so we want to show people how to protect themselves at home."

Why are molds a real estate deal-killer?

According to Vistainfo's Property Disclosure department, there are thousands of molds. At their mildest, molds can wrinkle the noses of buyers and cause coughing, sneezing, headaches or trigger respiratory ailments; at their worst, they can kill. Consider the deadly Stachybotrys mold, which when combined with exposure to cigarette smoke, can cause fatal bleeding in the lungs of babies under 12 months old.

The biggest problem with molds is once they have invaded a home, they can't be killed, particularly if the conditions that fostered the molds aren't changed. "You have to go to the source," says Giles. "After-the-fact pesticides will only temporarily halt the growth of molds if the conditions that caused the mold aren't improved.

When mold gets into wall, flooring or roofing structures, the repair costs can be tremendous. Recalls Newell of his lost sale, "The mold was so severe that the repairs would have meant removing the flat roof and putting in a sloped roof, at a cost estimated over $45,000 according to a couple of contractors. That's why my buyer walked."

How do you protect your clients and yourself?

According to Giles, most homeowners don't even know that they may have mold, so it is seldom that it will be found on sellers' disclosures. That means that before you represent a seller or a buyer on a home, you want to be sure that mold won't grow over your closing. Do the following:

• Be alert for signs of mold. Advises Giles, "Notice the basement and notice if there is water damage or seeping. Standing water breeds bacteria and fungi and it gets into the air and causes respiratory illness."

  Other red flags? If your nose or lungs don't alert you, look for:

  1. Musty, moldy smell
  2. Feeling of dampness
  3. High humidity
  4. Pets
  5. Rugs covering other floorings
  6. Any signs of respiratory discomfort in current residents
  7. Stains or signs of leaks indoors
  8. Mold on landscaping bordering the home
  9. Gutters in good repair to carry water away from the home.

  "Ask if there have ever been any leaks or flooding in the home," suggests Giles.

• Get your own inspection. Newell insists that his buyers get an independent inspection. He says he was suspicious because the pre-sale inspector never even entered the attic as the entryway was still painted shut. "I had to cut the paint line myself because it is against the inspection association rules for the inspector to do so," says Newell.

• Be prepared with solutions."You want to source control first," says Giles. "Stop the water from leaking, lower the humidity, and eliminate pets that are soiling the home. Second, open the windows. There's nothing like fresh air ventilation."

  Minor molds can be killed with bleach, but if a fabrication like a carpet or wood floors have been flooded or stained, they should be replaced.

And if all else fails? In worst cases, professionals may have to be called in to fix the problem. "There are certain things you can do to kill fungi," advises Giles. "but don't use biocides or pesticides as a short cut, or you'll have the mold back again. That's why we recommend source control and ventilation."