how to remove stale air from basement

This article discusses ways one can get rid of stale air from their basement. We first look into processes and activities that cause the air in basements to get stale, and how one can prevent as well as remove stale air.

Why is basement air quality important?

Basement areas are defined as enclosures placed directly under the building. These rooms are usually built below ground level, so they are prone to leakage problems, and usually lack adequate ventilation and heat. 

Basements are also prone to seepage issues, given the fact that they are below ground level. Lastly, basements are typically used as a storage room for items such as clothes, furniture, books and newspapers, and so on.

All these factors collectively create the microclimate that is best suited for rise in humidity levels, as well as the growth of mold on favourable surfaces.

Therefore, basements are prone to develop a stale air smell, given the environment it creates, as well as the lack of ventilation.

The air quality in these rooms is primarily affected by factors such as 

(i) various items stored such as unused furniture, solvents and chemicals used for cleaning or hobby purposes, paints, and gasoline products 

(ii) moisture content 

(iii) presence of mold and mildew

(iv) presence of furnace or boilers; and 

(v) dust and dander.

Furthermore, these rooms usually have very limited air exchange, which causes a build-up of PM within these rooms. 

Certain products such as furniture release emissions more or less continuously, while other sources (e.g.: smoking, air fresheners) release emissions intermittently. 

Given the nature and origin of the emissions, they can be potentially harmful when inhaled and can cause serious respiratory issues in the long run.

These effects are more pronounced in certain groups such as children, older people, and people ailing from respiratory and cardiovascular diseases. 

Thus, it is important to ensure the air quality of the basement is well-maintained.

Factors that favour formation of stale air in basements

There are a few chemical species as well as biological components that are responsible for making the air seem stale. These include:

  • Water vapour
  • Mold and mildews
  • Combustion processes
  • Poor ventilation
  • Household products

We shall discuss them in brief.

Water vapour

In higher humidity levels, the air becomes heavier than normal, making it harder to breathe. This can happen in basements where central boilers and heating systems are present.

Furthermore, water vapour also promotes the growth of microorganisms such as bacteria, mold, and mildew. These microorganisms further contribute to the odour, thereby making the air stale. 

Mold and mildew

Mold and mildew are fungal species that grow favourably under conditions such as presence of organic material, high humidity, low sunlight, and low temperatures.

These conditions are found in certain areas of the basement, such as corners, carpets, drywall, old clothes, books and newspapers, furniture, and so on.

The spores generated from mold and mildew, alongwith their odor, make the air feel stuffy and produce a stale or musty odor. 

Combustion processes

Some basements have furnaces where combustion of fuels and firewoods take place. Or in some cases, basements are used by smokers.

However, the PM generated by combustion processes may get settled in the basement air, and make the air seem stlae.

Poor ventilation system

Ventilation is an important feature in every house. Apart from the fact that adequate ventilation keeps the air fresh and prevents stale air, it also removes the indoor air pollutants by bringing in fresh outdoor air, while carrying the indoor air away.

However, some places lack adequate ventilation, which can happen due to various reasons. In such cases, the indoor air pollution keeps aggregating, and growth of mold and mildew can also take place.

In the case of basements which typically do not have a natural source of ventilation, articles such as clothes, furniture, and walls are more prone to mold and mildew than the other rooms of a  house.

Household products

Basements are typically used as storage rooms for common household items such as solvents and dyes, paints, furniture, and so on.

These products can give rise to certain gases such as volatile organic compounds (VOCs), formaldehydes, etc., which degrades the basement’s air quality, making the air seem stale.

Methods to get rid of stale air from basements

There are multiple ways in order to minimise as well as prevent the buildup of stale air smell within a room. Some of these are:

  • Opening windows and doors
  • Installation and regular maintenance of HVAC systems
  • Regularly cleaning your house
  • Investing in an air dehumidifier
  • Using an air purifier

Let us discuss these in more detail.

Opening doors and windows

Opening your doors and windows in the basements for some time during the day helps to increase the air exchange rate with the outdoor air.

As mentioned earlier, this helps to remove the indoor pollutants as well as the odor, while introducing fresh air.

However, it is important to check the outdoor pollen and mold count, since on days of high concentration levels, the smell will get further exacerbated.

To enhance this even more, it would be ideal to use table fans or exhaust fans which would further help to improve circulation of air in the basement with the other rooms as well as the outdoor air.

Installation and regular maintenance of HVAC systems

HVAC refers to Heating, Ventilation, and Air Conditioning. Although in some places it is already present, it might be the case that certain places may not have it.

HVAC systems are especially helpful for places which do not have proper sources of natural ventilation, such as basements. They help to regulate the room conditions in a manner that prevents growth of mold.

However, one should also ensure that the HVAC systems are being maintained on a regular basis, since faulty systems as well as older units may sometimes contribute to the stale air smell.

Regularly cleaning your basement

It is important to keep your house clean, especially surfaces such as beddings, carpets, or places where people usually are present.

Studies have shown that nearly 60% of total dust accumulated in the indoor air originates from outdoors. Within these dust particles, mold spores and other substances can be present, which cause indoor stale odor.

By regularly dusting surfaces and cleaning the basement, there are lesser chances of accumulation of substances that give rise to stale air smell.

Invest in an air dehumidifier

As seen from above, high humidity levels play a major role in the generation of stale air smell indoors. Therefore, it is important to regulate the indoor moisture levels.

This is where air dehumidifiers come in the pictures. These devices, as the name suggests, lower the humidity of the indoor environment, therefore keeping the air dry and hampering the growth of mold.

Use an air purifier

Air purifiers are devices that help to keep the air in an indoor environment clean. They not only remove pollutants that give rise to stale air smell, but can also remove the smell efficiently.

HEPA filters with an activated carbon filter as well as a germicidal UV light chamber are the best option for getting rid of the stale air smell in a relatively short amount of time.

However, it is important to note that air purifiers should not be used in high humidity conditions, as humid air is heavier than normal air, which causes overworking of the air purifier, thereby decreasing its efficiency.

Another reason for doing so is that the mold spores entrapped within the filters can start proliferating in there itself, which in turn can exacerbate the air quality.

Store household items with care

Household items such as paints, solvents, dyes, etc. should be closed properly and stored in cool places, in order to minimise the emissions from these products.

This not only helps to maintain a good indoor air quality in the basement, it also ensures that the occupants do not suffer from the side effects caused due to inhaling these gases.

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Stale air refers to the characteristic property of indoor air which has lost its freshness, and is associated with a certain musty odor.

Basements usually develop a certain microclimate which is characterised by dark and humid conditions and low temperatures, given that its position is below ground level.

This condition mainly arises from factors such as high humidity levels, growth of mold and mildew, inadequate ventilation, and certain household products.

However, one can easily get rid of this stale air from basements by improving the ventilation in basements, installing and regularly maintaining air regulating appliances such as air conditioners, air purifiers and HVAC systems, store household items which are prone to mold infestation with care and regularly cleaning the basement, and lastly, by using an air dehumidifier to bring down the humidity levels of the basement to an optimal range.


Do air fresheners and essential oils help to get rid of bad smells in the house?

Yes, air fresheners and essential oils can help to get rid of bad smells in the house. However, this is only a temporary solution, since once the effect of these fragrance compounds fades away, the sources of odors are still persistent, thereby causing the bad smells to occur once again.

As a solution, it would be ideal to rather identify the sources of unpleasant odors in your house and take care of them, as this is a viable solution that would last for a longer time.

Can musty smell in my basement happen due to seasonal variations?

Yes, the musty smell in your basements can also be linked to seasonal variations. In certain seasons, such as summers, springs, or rainy seasons, the humidity levels of the ambient environment goes up. 

These levels can lead to the growth and proliferation of mold and bacteria, which in turn produce the musty smell often associated with stale air.

Hence, it becomes even more important to use an air dehumidifier in such seasons, in order to keep indoor humidity levels low, thereby keeping in check the growth of mold, ultimately preventing stale air.

Why does my basement smell like gas but no leak?

This can happen due to the presence of sulfur in the indoor ambient air. Sulfur, like gas, has a characteristic rotten egg smell. This can emanate from sewage traps that are usually present in the basement level, or from organic discards as well.

However, it is not necessary that it will always be the case. Gas leaks are hard to spot, and even if it isn’t in your house, there might be chances that there is a leak in your neighbouring house.

In such a case, open all doors and windows, and contact a professional who can help better.


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