What’s wrong with a little mold and mildew? As long as they stay put behind the laundry tub, out of sight under the basement carpet, or only peek around the edge of the bathroom wallpaper, who cares? You should! They could be damaging your home and your health.

Here we’ll take a look at what mold and mildew are, how they affect the health of you and your house and, finally, how you can prevent their growth and get rid of the stuff.

Though there are thousands of different types of mold and mildew, they all have two things in common: The first is that their mission on Earth is to digest

the organic world around them. The second is that they all need moisture so their little digestive enzymes can go to work. There are differences between mold and mildew, but

for our purposes, we can call the entire gang mold. Molds are neither plants nor animals. They’re microscopic organisms containing enzymes (responsible for digesting and decomposing) and spores (in charge of reproduction). Mold dwells within the fungi kingdom: a realm that includes mushrooms, yeast and other seemingly unsavory characters. But the truth is, these decay organisms aren’t unsavory at all. Without them, toppled trees, dead animals and fallen vegetables wouldn’t decompose. Our land would get piled higher and higher with dead stuff. We wouldn’t have foods and medicines like cheese and penicillin. The problems arise when mold starts chomping away at things we don’t want them to—affecting the look, smell and structural integrity of your house.

Mold needs to consume something to survive, and it’s perfectly happy eating your house if you let it. Some molds and mildews are fond of the cellulose in the paper backing on

drywall, insulation and wallpaper. Others have a ravenous appetite for the glues used to bond carpet to its backing. Left unchecked, mold eventually destroys the parts of the drywall, wallpaper and carpet it attacks. But many molds just like to feast on the everyday dust and dirt that gather in the perpetually moist regions of your house. They won’t destroy your house, but they can sure make it look, feel and smell bad. Mold can mar your walls with white spider web-like growths or clusters of small black specks. It creates the smell we often refer to as “musty.” It can be slippery and dangerous when it grows on damp basement stairs. Molds rarely go so far as to rot wood or do structural damage—they’ll leave that to their fungal cousins—but they can wreak plenty of havoc.

We can’t overemphasize that mold needs moisture to get established, grow and reproduce. Mold problems and longstanding moisture or high humidity conditions go hand in hand. To conquer mold, you must also conquer moisture problems. Besides damaging your house, mold can cause severe health problems.

One consultant we interviewed confessed he crawls around in moldy places day after day, month in and month out, and never suffers ill effects. Others—some estimate about 10 percent of the population—are severely allergic to mold. It’s primarily the dinky reproductive spores that people react to. Twenty of them sitting side by side could fit across the period at the end of this sentence. That means they’re hard to filter

out. The spores also have an incredible “hang time” (as my teenage son would say); they’re able to stay suspended in midair for hours on end. That means they’re easily inhaled.

With even slight exposure to molds and spores, sensitive people may experience headaches, runny noses, skin rashes, nausea, sinus problems, memory loss and coughs. They may feel listless for long periods of time. In short, they feel as though they have a perpetual case of the flu. Newborns, the elderly, the sick, and those with compromised immune systems can be affected severely, even fatally. Babies and toddlers, who love to crawl around on possibly moldy carpets and stick possibly moldy things in their mouths, also are highly vulnerable to mold-induced illnesses. Super-sensitive people often go to extremes to rid their houses of the materials that harbor the dirt and dust that molds feed on. They’ll replace soft, textured materials with smooth, hard surfaces that are easier to keep clean and less likely to trap debris and moisture. Out go the carpets and draperies; in come hardwood floors and metal window blinds. Out go the cushy couches; in come the vinyl chairs.

Tightly sealed newer houses may be better at holding in heat, but they’re also more likely to trap moisture and spores. Mechanical ventilation, like an air-to-air heat exchanger, is

critical for healthy air quality in tightly sealed new homes

Step one in getting rid of mold is to fix the moisture problem that’s setting the stage for its growth. This is key. You can scrub, dispose of and replace moldy materials, but until you fix the problem, mold will keep returning. The fix can be as simple as sealing up leaky air-conditioning ducts or as daunting as reshingling a leaky roof or regrading your yard so water runs away from, rather than toward, your foundation. Sewer backups and floods also set up ideal environments for mold and mildew growth

Once the moisture problems are fixed, get rid of the moldy materials carefully. Rough handling of damaged materials will not only stir up spores and spread them even farther around your house but also launch zillions of spores into the air, where you’ll inhale them. One square foot of moldy drywall can harbor more than 300 million mold spores; slamdunk that onto the basement floor and you’re just opening another Pandora’s box. Even dormant spores inhabiting driedout materials are irritating to inhale, and if they find moist environs again, they can zip back to life and establish new colonies. After removing all damaged materials, scrub all remaining hard surfaces with a ½ percent household bleach solution.