Everyone knows that musty house odor is coming from somewhere. But where? Let's find out how to neutralize it. "Hmmm, kinda has that old house smell". Those dreaded words evoke something rather frightening and repellent to most homeowners. You know what we're talking about, right? It's that musty odor that creeps up and greets you the instant you set foot inside an older home. What is this mysterious stench, anyway? And more importantly, is there a way to get rid of it? Well, we are turning to science to find out.

What causes that old home smell?

"Three things that musty old houses have in common: little ventilation, high humidity, and darkness," says Bill Carroll Jr., an adjunct professor of chemistry at Indiana University. That makes these places the perfect petri dish for mold to flourish, which happens to be the main purveyor of that "old house smell." That said, what you’re smelling isn't mold per se.

"What you're smelling are called MVOCs: Mold Volatile Organic Compounds," explains Carroll. "These are chemicals associated with a certain stage in the mold life cycle that are volatile enough to evaporate, but also have a strong enough inherent odor to be detected. The good news is that this funky smell isn't a health issue", says Carroll. "It’s just annoying — and probably more than a little embarrassing — particularly if you're trying to sell your house to people who wrinkle their nose as soon as they enter your home. Luckily, though, there are ways to get rid of the funk."

How to remove old house smell: Dry the place out

"Opening up the windows and airing the place out - like your mother did when spring came - can help,” says Carroll. If your house tends to be humid and you’re sure you don’t have any leaks, "keep your air-conditioner or a dehumidifier running," suggests Carroll. Oh, and if you do have a leak of some kind - even if it's just a leaky faucet? "That needs to be fixed before any progress can be made," notes Carroll. (Progress meaning "fresh-smelling house.")

Let the sun shine in

"Light, especially sunlight with its ultraviolet component, is a good disinfectant," Carroll notes. "After all, UV is used to disinfect water in some pool systems."

Clean your couch

Sorry to be the bearer of bad news, but if that old house smell is coming from your couch, it may be more of an "old couch smell" instead. In fact, all upholstered furniture and your carpets could be culprits. "Soft stuff absorbs ambient moisture," says Carroll, which can lead to mold growth. Softer materials absorb "ambient moisture," says Bill Carroll Jr. "Worst case, all the soft stuff has to go or be professionally deep-cleaned," he says. If you work hard to reduce the humidity in your house, over time, the soft stuff may relinquish some of its ambient moisture as well, dry out, and start resisting mold growth. "But that takes time, because it takes a while for the moisture deep inside the furniture to migrate out," Carroll says. "And a good cleaning of the hard surfaces with a disinfectant doesn’t hurt either."

Deep-clean the guts of your house

"Furnaces and air ducts can have a tremendous amount of mold that can grow in them when they’re not being used," says Leslie Reichert, cleaning expert and author of "The Joy of Green Cleaning." Not to mention that air-conditioners can also trap mold and mildew in their filtering systems. If you think these little tunnels are the source of the smell in your home, hire an HVAC professional, who can actually use a tiny camera to make sure all the gunk is located - and removed.

Declutter under every sink

"Nope," you may be thinking. "I don’t have any leaks." But if you’ve got a gazillion cleaning supplies and sponges under your kitchen sink and two gazillion beauty products, would you really know? So clean it out. "Getting things out from under the sink lets you see if anything is dripping or molding," says Reichert. "Also, you can check for dampness or leaking in the piping."

Wash your walls

Walls can waft an old house smell, too. Reichert advises dissolving a half cup of borax in a bucket of hot water (32 ounces), then adding 2 cups distilled white vinegar and 16 ounces of hydrogen peroxide. Right away, wipe down your walls and let them air dry. "This will remove grease, dust, and mildew, and also remove smells that have embedded into wall surfaces or wallpaper," Reichert says. Repeat whenever you catch a whiff of a "stale" smell. 

Neutralize the air

An open container of baking soda or white vinegar, kept in an unobtrusive place (for example on top of your kitchen cupboards), can help absorb smells and clear the air. Experts also recommend FreshWave or DampRid, two all-natural substances that absorb smells and trap excess moisture in the air.

* Perfection Cleaning does not guarantee or warranty any suggested cleaning methods. Use at your own risk.