First, it was asbestos. Next, it was radon. And now, the bogeymen of the real estate world are mold and mildew. And even though these pests have been around this planet since time's beginnings, they are now considered a life-threatening hazard to you and your family.

Mention mold on an inspection report, and the sale is likely canceled. Find it in new home construction, and the builder may be better off burning the structure and starting over. How it got to be that way, I honestly can't say.

For many years, the "Ask Heloise" solution for clearing up mold and mildew was to mix 1 gallon of warm water with a cup of household bleach, then rinse and scrub the affected area. But today, we are confronted with a phalanx of mold-and-mildew remediation experts, ready to solve all such problems for a price.

It turns out that mold is easier to prevent than it is to clean up. In order for mold and mildew to be happy, they need moisture, warmth and a food source (almost anything organic including dust, paper and wood). If you can eliminate any one of these three conditions, the mold can't grow. Eliminate all of them, and you are guaranteed to have no problem at all.

I recently came across a pamphlet from the University of Georgia Cooperative Extension Service titled "Preventing Mold in Your Home," and I found its advice quite helpful. The entire report is available as a free download on my money99.com Web site, along with additional information.

The primary cause of household mold and mildew is excess moisture. This can be caused by leaky plumbing, excessive humidity or poor drainage. Poorly ventilated interior bathrooms and showers often present all three of these conditions.

Getting the right "moisture balance" in your house is important to preventing molds. Jorge Atiles of the UGA Extension Service describes the four factors we should examine:

•Source strength refers to the sources of moisture inside your house. The best way to reduce these sources is often to limit the amount of time spent washing, bathing or cooking, especially cooking involving lots of boiling. Also, correcting leaky pipes or drains can be a great help. I was surprised that the report finds portable dehumidifiers typically ineffective because they have a tendency to add back heat into the environment, which contributes to mold growth.

•Temperatures, both warm and cool, can contribute to mold growth. The cooler the indoor surface, the greater the degree of condensation. Thus, shower stalls and window sills are frequently mold problem areas. In addition, higher-temperature air can hold more water vapor, contributing directly to moldy conditions. So a whole-house dehumidifier may be needed.

•Moisture transfer rate refers to the passage of moisture in and out of your home. Here newer homes will have the edge, as they are built much tighter. But that same tight construction may be holding in excess moisture, as well as keeping drier air out. Replacing drafty older windows, sealing air leaks around doors, weatherizing before insulating, and using a vapor barrier in crawl spaces can effectively alter your home's moisture transfer rate.

•The circulation and ventilation rates of your home will also impact indoor moisture. Installing HVAC supply vents located to promote circulation, and using exhaust fans to remove excess moisture (such as in the kitchen and bathroom) can improve your home's circulation/ventilation rate. I once managed a vintage rental house in which the bathroom was plagued with mold and mildew. Then I installed a ceiling fan in place of the light fixture and asked the resident to run the fan for an hour after each shower or bath. Apparently, the increased circulation helped eliminate the problem.

I have come to the conclusion that keeping mold under control is an ongoing chore and, in the vast majority of cases, one that can be accomplished by the average homeowner with vigilance and common sense.

Next week: Common questions and answers on mold and mildew.

Find more articles by John Adams on the ajchomefinder Mortgage Center.