Imagine entering a room that has been closed for weeks: before turning on the light, an indefinite smell reaches your nostrils, a mixture of “damp” and “lived”, what we define a musty smell. Well, what we smell really exists on a chemical level: it is the result of the accumulation of a series of volatile molecules (VOCs) – chemical compounds that easily “fly” into the air in the form of gases that we can smell – which we would not normally perceive if the room was well ventilated. Among those responsible are VOCs emitted by materials from furniturepaints and detergents; but also VOCs deriving from mold and bacteria (and called mVOCs, because of microbial origin), which act in stagnant environments. Finally, we human beings also contribute to that classic musty smell with our own emissions (breath, dead skin and sweat) who remain trapped in the apartments. In general, the smell musty it is not toxic itselfbut it represents a sign that the air is not being renewed correctly: it is therefore good to take small precautions to avoid prolonged exposure, such as open windows often and ventilate, keep humidity low And constantly clean furniture and carpetsso as to prevent mold (the real cause of the smell) from growing.
Why a house can smell: the causes of the musty smell
Everything that makes up the room – furniture, carpets, paints, curtains, clothes – release constantly tiny molecules in the air, even when no one is present. The continuous emission of volatile molecules into the air includes relatively light organic substances that evaporate even at room temperature. Let’s imagine a wardrobe full of clothes washed months ago: the fabrics hold detergent residues and softeners, the fibers slowly release other molecules (dyes, fabric residues) which detach and, in the absence of fresh air, everything remains suspended in there, ready to welcome us with that unmistakable note. The same goes for much else that we can find in a closed place. The paintsfor example, are made up of numerous chemical components: from glues to dyes, up to antioxidants… all compounds which, again, are gradually released into the air and there they remainif we do not ventilate the room.
In addition to this, thehumidity plays an important role: higher levels of humidity favor volatilization and the release of VOCs from materials, so ventilation is fundamental but it is not the only factor at play.
Another large component of musty odor comes from two less obvious sources, in addition to inanimate materials: i microorganisms (molds, bacteria) that produce further volatile compounds and human emissions (breath, sweat, skin).
Molds and bacteria present in closed or humid environments produce so-called volatile compounds mVOC (microbial volatile organic compounds), just like VOCs but of microbial origin. In fact, it would appear that although material VOCs dominate, mVOCs may be the ones that dominate olfactory sensation in humid or moldy environments.
We humans are also producers of chemistry in the air: breathing, skin, sweat they release volatile organic compounds such as isoprene, acetone, fatty acids, ammonia. In a closed environment, where the air is not changed, these emissions remain trapped, mixing with the VOCs of the materials and the mVOCs of the mold: the result is always that smell that we call “stuffy”. It’s as if every “inhabitant,” every piece of furniture and every microorganism in the room adds a chemical splash to the environment.
How to eliminate the musty smell in the apartment: practical remedies
The musty smell it is not toxicespecially because it is unlikely to be exposed to it for a long time (after all, who doesn’t get short of breath after some time in a room that has been sealed for weeks?), but it is still good to maintain a some attentionavoiding breathing VOCs for too long, which in some cases could cause discomfort and respiratory tract irritation. Here are some suggestions deriving not only from common sense and data present in studies, but also reported by the United States Environmental Protection Agency (EPA) to reduce the quantities and effects of these VOCs in our homes:
- open the windows to lower the concentration of molecules in the air;
- check the humidity: if it is above 60-70%, microbial growth and the consequent production of mVOC may increase, with odor production;
- clean and air furniture, carpets, closed cabinets.
In short, unless we open an Egyptian sarcophagus from 3000 years ago, it doesn’t take much to stay away from that musty smell.
