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What Causes Stale Air in Homes and Buildings?

When you return home after a vacation, or walk into a space that is difficult to ventilate well — like a basement or attic — you may immediately be overwhelmed by a distinctly unpleasant odor as well as a feeling of discomfort. Often called stale air, all your senses tell you that something isn’t quite right when you breathe it in. You’ll have the urge to leave the space as soon as possible or to open all the windows.

What are the underlying causes of this stale air, though, what types of compounds might be found in this type of air, and what can you do to combat stale air?

What Is Stale Air?

Air stagnation — a situation where the same air is present in a space over prolonged periods of time — can be a problem even in the environment outside, in which case lack of wind and rain is the cause. When an indoor space lacks airflow, the chemicals, particles, and organic compounds the air is exposed to cannot be cleared out by an influx of new, fresh, air. Over time, this becomes noticeable in the form of a stuffy, dusty, and smelly indoor environment, where humidity and heat may have built up as well. This type of air is commonly called stale air or stagnant air.

The precise makeup of stale air can vary enormously, as it depends on the substances the space is exposed to. In general, however, stale air contains the very same compounds that are usually a threat to indoor air quality — but now in much higher concentrations. They include:

  • Particulate matter — solid and liquid particles floating in the air — of various sizes. These particles may come into homes and other indoor spaces from outdoors, but also originate from within the property itself. Stoves, heaters, and tobacco smoke are three examples of common sources of harmful particles.
  • Volatile Organic Compounds, hazardous gases released by solids and liquids alike. VOCs are going to be present in every home, but in the case of stale air, the concentrations rise significantly. Sources include building materials, furniture and indoor fabrics (such as bedding, couches, carpets, and curtains), cleaning materials, air fresheners, paint, paint strippers, glue, and stored fuels. Acetone, benzene, and formaldehyde are only some of many examples of common VOCs.
  • Carbon monoxide, which is not technically considered a VOC, can also build up within a space, due to poorly-maintained chimneys, smoking, and cooking activities, for instance. While this highly-hazardous gas is both odorless and invisible, it poses a large threat.
  • Carbon dioxide is another gas commonly associated with stale air; as people naturally exhale this gas, larger concentrations are most likely in very crowded spaces that also suffer from poor ventilation.
  • Radon, a naturally-occurring but highly-dangerous gas that may be emitted by soil, stone, and other organic materials. Exposure to high radon levels is the leading cause of lung cancer in the United States after smoking.
  • Asbestos. If you live in an older home, especially a home constructed before 1980, your property may contain asbestos, which would commonly be found in shingles and flooring. Although asbestos is a large threat, it will primarily be released into the air when it is interfered with.
  • Household dust, which can include pet dander (dead skin cells shed by animals) even if you do not have a pet, along with insect droppings and numerous types of particulate matter.
  • Grass and tree pollen, the presence of which can provoke immediate reactions in people who suffer from allergies.
  • Bacteria and viruses. Pathogens can build up in a space over time, too, particularly in rooms frequented by large numbers of people.
  • Mold. High humidity levels are, in themselves, a source of discomfort among people entering a space with stale air; humidity will make you feel “heavy” and tired. If a space is humid, the other major risk is that mold will have taken hold there. Very often, a mold infestation will produce a characteristic musty odor that would immediately lead you to describe the air as “stale”.

How Can Stale Air Impact Your Health?

The extent to which stale air can impact your health depends on how much time you spend exposed to it. In the short-term, healthy and young people may experience mild discomfort such as an irritated throat, coughing, headache, and nausea. These symptoms are likely to subside very soon after you manage to get some fresh air, however.

In people who have chronic health conditions such as asthma or allergies, however, even short-term exposure to stale air can be a more serious problem. Extremely poor air quality is likely to immediately worsen preexisting symptoms, and some people will suffer from extreme shortness of breath and asthma attacks.

Some of the most dangerous compounds found in unhealthy and stale air further have the potential to cause serious long-term health complications, though. People who are exposed to very poor indoor air quality  for prolonged periods of time, such as years, may have an increased risk of liver damage, certain cancers, chronic lung and heart disease, and kidney problems.

If you know that your home or workplace has a stale air problem, this should be enough to make tackling that fact and improving air quality a top priority.

What Can You Do to Combat Stale Air in a Space?

Combating stale air does not have to be difficult or costly. In fact, it is often possible to significantly increase the quality of the air in a home or other building by simply making full use of resources that you already have. When HVAC systems work correctly, the outdoor vent has been opened, and the filter is replaced sufficiently frequently, they do a lot to ensure that the air in a space is fresh. A more low-tech way to immediately increase ventilation — allowing the buildup of noxious chemicals and harmful organic matter to escape — would be to simply open all the windows, and keeping them open for as long as possible.

Additionally, you could consider investing in window fans that specifically rid a space of stale air, and purchasing exhaust fans in kitchens, bathrooms, and laundry rooms — or, of course, consistently using those you already have. These three rooms have the highest risk of chronic humidity. That means they are also extremely likely to attract mold growth, unless you take proactive steps to lower humidity levels and increase ventilation.

Finally, a true HEPA air purifying system designed to adequately meet the demands of the target area can have a tremendous positive impact on your indoor air quality. As these air purifiers filter out over 99 percent of particulate matter, including the most dangerous kinds, their use instantly renders the air cleaner and healthier. Those air purifiers that additionally have a carbon filter can also, meanwhile, help to fight the presence of VOCs.

Do You Need a Mold Inspection in Your Home or Workplace?

When you’re asked to imagine the smell of “stale air”, chances are very high that your mind will wander to moldy spaces like damp basements or attics. Although stale air can build up in absolutely every space that lacks adequate ventilation, spaces in which all the common-sense steps already described above have been taken but that still smell stale could easily have a mold infestation.

Don’t make the mistake of believing that you cannot have a mold problem if you are unable to see any mold in your home or commercial property. Although mold can take hold in a space very visibly, with apparent growth on ceilings, walls, and other surfaces, mold growth can also be hidden. In these cases, mold may build up around leaky pipes or in areas subject to condensation. Mold may even be present in the very HVAC system you are using in an effort to cleanse your air, in which case your air condition may be releasing toxic and allergenic mold spores into the air with every breath you take.

It would be prudent to consider having a professional mold inspection carried out if the air in your home or workplace chronically smells and feels stale or stagnant. MI&T’s independent mold inspections will comb through all the potential problem spots within your property during our visual mold inspection. We then take air samples that will shed light on the exact cause of your stale air. If MI&T finds that harmful mold species are present, we can advise you on the steps you would need to take to fully remediate the mold infestation.

As a mold inspection only company, MI&T is free from the commercial biases you would encounter if you were to call a mold remediation service for your mold inspection. We are, however, there for you every step of the way; after your mold remediation plan is complete, MI&T can return for clearance testing that lets you know if your mold problem is now truly a thing of the past.