Does a basement need an air purifier and a dehumidifier?

In this article, we discuss why do you need an air purifier as well as an air dehumidifier if you have a basement level in your house.

Does a basement need an air purifier and a dehumidifier?

Yes, basements require an air purifier as well as a dehumidifier, especially if the ventilation in the room is not adequate. They help to keep the air clean as well as prevent the formation and spread of mould.

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. 

These factors play a major role in increasing the relative humidity of the room, which favours the growth of mold and mildews. 

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.

Air dehumidifiers

Types and working mechanism

Dehumidifiers dry out the air. This is essential in general, in certain seasons such as summer and spring, when the ambient humidity levels rise up to 60%. 

There are mainly four different types of dehumidifiers, which include:

  • Refrigerative
  • Electronic
  • Desiccant
  • Ionic

A refrigerative dehumidifier operates by using a fan to suck warm air currents into its coils. Warm air condenses when it passes through the machine’s chilled coils, leaving condensation inside the dehumidifier.

As the condensation gathers, one droplet of water at a time, it falls into a dehumidifier-connected storage tank. Through the opposite side of the machine, cooler, drier air is sent back into the house.

The other common type of dehumidifier is a desiccant dehumidifier. This is a considerably more powerful dehumidifier, however it’s mostly used in commercial storage for medicines, food, and chemicals. 

It can lower humidity levels by 45 percent to 1%, however it does so by relying on thermal energy (natural gas or steam) rather than electrical outlets. 

Desiccant dehumidifiers employ chemical attraction instead of condensation to reduce humidity levels.

How dehumidifiers help in basements

Rooms which are prone to moisture build up such as bathrooms, kitchens, and basements require an air dehumidifier.

The specific micro-climate conditions of high humidity levels and low temperatures in the basement directly contribute towards processes that lead to deterioration of indoor air quality. 

Elevation in humidity and temperature favours the growth of mold, which produce spores that act as biological air contaminants.

Mold and dust mites that grow in excessively wet air produce spores and droppings. These products can cause allergic responses and trigger severe asthma symptoms, especially in people prone to it.

An air dehumidifier has the ability to reduce the humidity in the air to 30 to 50 percent relative humidity. Many dehumidifiers come with a metre that monitors the relative humidity in the area where they’re installed, and you may adjust the humidity to the desired percentage.

Not only that, dehumidifiers also help to remove the suspended dust in the basement air, which can aggregate due to lack of proper ventilation.

However, dehumidifiers are not efficient in removing all dust particles present in the basement air. Furthermore, dehumidifiers can only keep in check the agents that cause musty odor in the basement, but not get rid of the odor itself.

How air purifiers help in the basement

A major component of basement air pollution is particulate matter (PM). These particles can originate indoors from various sources, or enter the basement from the outdoor air. 

PM has serious implications on health, depending upon its composition and abundance, and can also cause premature death in people ailing from respiratory and cardiovascular diseases. 

The best method for reducing PM concentrations is by using an air purifier. Depending upon the size of the basement, an adequate air purifier should be used. 

Air purifiers can remove particulate pollutants more than or equal to 0.3 microns with more than 99% efficiency. 

Furthermore, air purifiers can also get rid of musty smell and other gaseous pollutants that can arise from various sources in the basement, thereby making the air less repulsive in terms of odor.

Air purifiers can also get rid of mold and bacteria spores that can be suspended in the air, along with dust particles. This helps to keep the proliferation of mold in check, and also prevent increase in the number of dust mites as well.

However, it could be harmful to run an air purifier in humid conditions. This is because humid air is “heavier” in terms of adequately moist air, which can adversely affect the proper operation of the air purifier.

Furthermore, the dark and humid conditions that develop in the filter can serve as an excellent breeding ground for the mold and bacteria that were trapped earlier, thereby further exacerbating the efficiency of air purifiers.

There are different types of air purifiers that are commercially available in the market. Some of the most common air purifiers are:

  • HEPA filters
  • Air ionisers
  • Activated carbon filters

Air purifiers with HEPA (High-Efficiency Particulate Air) filters are best suited for indoor purposes. The presence of an activated carbon filter and a germicidal UV light chamber further increases the efficiency of the filters.

We shall talk about these two in more detail below.

HEPA filters

These air purifiers are also known as passive air purifiers. They simply pull in air from the indoor air, pass it through the filter, and release the purified air back in the enclosure.


The HEPA filters are very popular nowadays, as they have an efficiency greater than 99% against particles that are equal to or greater than 0.3 microns in diameter.

These air purifiers also help to get rid of odor-bearing substances such as smoke particles, dust, volatile organic compounds (VOCs), and so on.

Side effects

In the current scenario, the covid pandemic has been a prevalent issue. Studies have shown how the virus can spread indoors from infected articles to healthy people. Hence, prevention is necessary.

Furthermore, HEPA filter air purifiers fail to catch virus particles, since the typical size of a virus is less than the effective range for the air purifier’s functioning.

For cases where the air purifier is installed in rooms with high relative humidity, one of the common substances to get trapped in the air filter would be mold and bacteria.

If the filter is left on at all times, the amount of water vapour that gets entrapped in the filter will also increase. This provides the optimal dark and humid condition within the filter itself that promotes the growth of mold and bacteria.

Not only will this reduce the efficiency of the filter, it will also serve as a breeding ground for mold and bacteria, which in turn would be propagated through the air purifier.

Activated carbon filters

Activated carbon filters are thin membrane like filters which help to get rid of gaseous pollutants as well as other undesirable gaseous species.


Activated carbon filters are the best when it comes to getting rid of odors, irrespective of its nature and constituents. They are usually included as an additional component in air purifiers with HEPA filters.

The activated carbon filter absorbs the odor and gaseous pollutants present in the indoor air, when it is made to pass through the filter.

Not only does it help to get rid of odors from various sources, it also helps to get rid of dangerous gaseous pollutants such as radon and carbon monoxide, both of which can be lethal when one is subjected to elevated concentrations of these.

Side effects

Activated carbon filters are very thin and flimsy. This can cause
Them to be easily damaged. Therefore, such filters cannot be used as a stand alone filter.

Furthermore, these filters are very sensitive to particle loading, and tend to get overloaded quite easily with respect to the HEPA filters.

Which air purifier is the best for a basement?

Therefore, for people living in these areas or visiting these areas, it would be useless to use or buy an ioniser air purifier.

Therefore, your best bet would be using an air purifier which uses both, a HEPA as well as an activated carbon filter. This helps to get rid of particulate matter as well as odours present in the air.

Ways to prevent and minimise the side effects

HEPA filter air purifiers are meant to make life easy and the air clean for the user. However, we have seen that in some cases, it can have the opposite of the desired result.

However, these issues have solutions which help to minimise or prevent them from happening in the first place. These methods include:

  • Regular maintenance and replacement of HEPA filters.
  • Pairing it with other devices under certain conditions.

We shall discuss the importance of these methods.

Regular maintenance and replacement of HEPA filters

It is ideal to get your air purifier serviced on a regular basis by the technicians, as it is beneficial for the long run. This is also very helpful since any latent issues could also be identified and dealt with before it becomes a menace.

Pairing it with other devices under certain conditions

When using an air purifier in unfavourable conditions, it would be ideal to first use appliances that help to alleviate those conditions in order for the air purifier to perform efficiently.

For example, if the indoor humidity levels are too high, one should first use an air dehumidifier in order to bring down the humidity conditions to an ideal range, after which the air purifier should be used.


We discussed how air dehumidifiers help to keep the humidity levels low in a basement, therefore preventing any chances of mould formation and development of musty odour.

Furthermore, air purifiers with HEPA and activated carbon filters help to get rid of particulate matter (PM) and odours that may be present in your basement.


Where should I place my air purifier?

Ideally, you should place your air purifier in a location where the highest rate of air exchange takes place. Air exchange refers to mixing of two different types of air, which in this case refers to indoor air and outdoor air, and from one room to another.

This is because most of the pollution inside the house comes from outdoor sources. This in turn could spread to other rooms of the house. Hence, by placing an air purifier here, spread of pollutants within the house gets hampered.

Furthermore, the ideal place to keep an air purifier is to mount it on a wall, ideally 3-5 feet above the ground. This is because air moves horizontally as well as vertically, and this placement would ensure that the particles present in either air motion get successfully trapped by the air purifier.

How often should I replace my air filters?

The frequency of replacing your air filters depends upon the indoor air quality of your house. If you live with a small number of people, have pets, and are near a polluted area, you might need to replace your filters as early as 1-2 months.

However, if you live alone with no pets or other animals, you can replace your filter once every 6-12 months.


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