How to improve the air quality in your basement?

The below article talks about air quality in a basement, why it is important to maintain proper indoor air quality, how poor basement air quality can be a health hazard, and the next steps to improving air quality in your basement. 

How to improve the air quality in your basement?

You can improve the air quality in your basement by doing the below things

  • Installing an air purifier 

This would clean out the basement air by stripping out the toxic particles and contaminants using different types of filters. Keep in mind that the capacity of the air purifier needed will depend on the size of your basement.

  • Installing a dehumidifier 

This will remove the extra moisture and lower the humidity in the basement, and will stop any mold or mildew infestation. 

  • Installing a mechanical ventilation system 

This is a long-term investment and is the better option in the long run. Mechanical ventilation systems promote air circulation by bringing fresh outdoor air into the basement and flushing out the stale air.

  • Sealing any gaps and cracks

Sealing gaps and cracks in the basement using expanding foam or caulk, will stop the in-flow of any toxic particles or contaminants, dirt, and debris into the basement. 

  • Removing high VOC items

Storing high VOC items like paints, varnishes, lacquers, cleaning products, polishes, tints, etc. in outdoor sheds or garages rather than the basement will drastically improve the basement air quality. 

  • Waterproofing the basement

Waterproofing the basement will stop any seepage of water or moisture into the basement, thus keeping mold and mildew away, and protecting any items stored in the basement. 

What do you need to know about the air quality in your basement? 

Have you wondered why your basement smells weird, and starts sneezing uncontrollably or your nose and skin start itching when you go down to your basement? 

Basements are notoriously well-known to have the stale and musty “basement smell”. This musty odor emanates from the poor air quality in your basement, which has been an increasing area of concern with respect to indoor air quality. Basement air can have a large number of toxic mold and mildew particles, allergens, dust, and debris, etc. leading to a compromised air quality that can be a health hazard. 

The Environmental Protection Agency (EPA) notes that indoor air quality can be 100x worse than outdoor air quality (RTK, n.d.). 

While mold and mildew are quite often visible in unfinished basements, it is not visible in a completely finished and clean basement, but the musty smell would be an indicator of the fact that the air is compromised, and it be must be noted that this air would travel along with vents and filters, bringing in toxic particles into the air in other areas of your house. 

Since basements are usually built keeping in mind the need for storage space, elements like ventilation or proper airflow are not considered. 

Why is basement air quality important?

Toxic polluting particles found in basement air are fine enough to enter our respiratory systems and eventually the bloodstream. 

It is also to be noted that stored utilities in a basement can contribute to poor air quality as they break down over time, creating particles of sizes between 0.3 and 10 microns. These particles deposit in the lung tissue through respiration, and with high enough concentrations cause a long-lasting health hazard. The smaller the particles, the easier they enter the bloodstream or travel through vents and other spaces contributing to the poor air quality within your home. 

The stagnant air conditions coupled with dampness, poor air circulation, and ventilation forces us to breathe in toxic particles repeatedly. Some symptoms that show when the air quality in your house or basement is poor are the following (Poslusny C., 2021) (RTK, n.d.):

  • Disrupted sleeping patterns 
  • Headaches
  • Stuffiness
  • Nausea and dizziness
  • Increased number of allergic reactions
  • Eye, nose, skin, and throat irritations and itching 
  • Dry cough

Prolonged exposure to conditions of poor air quality could lead to “Sick Building Syndrome (SBS)” and “Building Related Illness (BRI)” in the occupants. SBS refers to when occupants face acute health concerns and discomfort resulting from prolonged inhalation within areas with bad air quality (EPA, 1991). 

SBS could present as physical symptoms that are listed above. BRI refers to when the prolonged exposure to bad indoor air quality has caused diagnosable illnesses that may have long-term health impacts, and these can be directly attributed to exposure to indoor airborne toxic particles (EPA, 1991). 

BRIs include VOC poisoning, cancer, asthma, hypersensitivity pneumonitis, infections, etc. (CDC, 2007). 

SBS and BRI could also be triggered by the poor air quality in constricted work environments, classrooms, ineffectively ventilated rooms or halls, excess presence of chemical or biological contaminants, etc. (EPA, 1991).    

What are you breathing in? 

Basements are not cleaned or vacuumed as often in comparison to other parts of our house. Therefore, there is a build-up of various substances such as:


Mold thrives and grows in damp environments leading to infestations that could have dire effects on health. 80% of SBS is contributed to mold infestations, the most common form being the black mold (RTK, n.d.). 

Volatile Organic Compounds (VOCs): 

Various old buildings have been found to use unsafe paint and asbestos, while this is being rectified in the larger common areas; they are usually ignored in the lesser-visited spaces like a basement. Therefore, particles like lead dust, radon, other carcinogens, etc. would be present along with other particles originating from old upholstery, adhesives, paints, carpeting, varnishes, old furniture, pesticides, cleaning products, gym machines, gardening equipment, etc. 

Fiberglass particles

Fiberglass insulation is commonly used in basements and is one of the major contributors to poor basement air quality. Since fiberglass is present all across ceilings and walls, there is very little effort made to reduce the impact caused by breathing in small glass particles. It is also used in the manufacture of piping, sports equipment, fire protection equipment, drum sets, etc. So, breathing in fiberglass doesn’t necessarily originate from insulation, it could be a breakdown of particles from items stored in a basement. 


The dust, mites, pollen, vermin and its droppings, mold spores, bacteria build-ups, mildew particles, etc. are some particles that can trigger allergic reactions. If there is equipment like washing machines and dryers, chances are lint is being inhaled as well. Not cleaning equipment could trigger infestations that spread rapidly across stored items in a basement, leading to increased breakdowns of toxic particles. 

Chemical fumes: 

Fumes from paints, pesticides, cleaning products, bleach, varnishes, gas, solvents, etc. emanate strong chemical fumes. These fumes could cause inflammation to the outer skin as well as to lung tissue and can contribute to poisoning or cancer due to long-term exposure. A radioactive chemical that is often present in basements is radon. Radon has been found to be the 2nd largest contributor to lung cancer in the US, with an average of 21,000 deaths every year (EPA, n.d.). Since radon is odorless and colorless, poisoning from radon is usually identified quite late. 

How to improve the air quality in your basement?

Rectifying the poor air quality in your basement can be done through the following steps: 

Clean the air: 

The easiest method and most common method employed is to purchase an air purifier. An air purifier would circulate the air through various filters to strip out contaminants or other toxic particles, to give out clean air. It is important to note that the most effective air purifier to improve basement air quality would include a True HEPA Filter, an activated carbon filter, and UV; a combination of these elements would lead to the removal of ~99.97% of toxic particles and contaminants (Dyson K., 2021) 

Product nameWhy I recommend it
SilverOnyx Air PurifierBest for large basements: finished or unfinished5 stage air cleaningA filter cartridge with a mesh pre-filter to trap the larger particlesTrue HEPA H13 Filter that captures 99.97% of contaminants UV light to kill mold, virus, and bacteriaActivated carbon filterAn ionizer that strips out toxic airborne particles and helps extend the life of other filters while freshening the airCylindrical shape of the device provides 60% more efficiency that falter devicesGives an alert when the filter needs to be changedFilters can be cleaned or replacedA timer that can be set for up to 24 hoursCovers upto 500 sq. feet 
Molekule Air PurifierDifferent sizes and types are available to cover rooms from 250 sq. feet to 1000 sq. feetWi-Fi enabled 2 year limited warrantyExtremely powerful in terms of destroying basement pollutants at a molecular levelEliminates all traces of pollutants with upto 99.99% efficiency360° Air intake Air flows through the outer filters to trap larger particlesInner filters destroys the smaller particles at its core using PECO technology; which is capable of removing contaminants 1000x smaller than what could be removed using a standard HEPA filterNanocatalyst coated filters will react to light to destry the contaminants, to produce purified, clean, and fresh air No ozone byproducts Captures contaminants, oxidises them and breaks them down to destroy them Molekule Air Mini has found to remove 99.99% of COVID-19 virus in the air, within one hourMolekule Air Pro removes the same and other proxy viruses which could travel via water droplets within 30 minutes
MINUSA2 Ultraquiet Air Purifier from RabbitAir 6 Stage FilterationPre-stage filter to trap dust mites, larger contaminants, pollen, pet hair, etc. Medium filter to trap bacteria, dander, dust particles, mold, fungi, pollen, etc.BIOGS HEPA filter is more efficient than the traditional HEPA filter as it reduces the probability of mold or virus growing on the filter and prolongs the filter’s efficiency; BIOGS HEPA filter is more efficient in reducing fumes and particles that carry diseas-causing viruses Ability to customize filters to meet specific needs including germ defense, pet allergens, odour remover, toxin stripping, etc. Activated Carbon Filter made of granular activated carbonNegative ions that latch onto smaller air-borne contaminants, so that they would be weighed down and trapped into the filters5 year warrantyCovers upto 815 sq. feetWi-Fi enabledSpecialized app services Wall- mountable Multiple customizable options


The musty smell usually is due to mold or mildew infestations that are triggered by the increased moisture in the air. A dehumidifier will dry out the basement, by removing the extra moisture in the air to lower the humidity and stop any mold or mildew growth in a basement.  

Product nameWhy I recommend it
hOmeLabs HME020006N DehumidifierComes in varying sizes and can cover upto 4,500 sq. feetVariations with respect to the amount of water that can be drawn from 14 litres to 40 litresCan be set to run continuously Removable water tanks Option to connect drain hoses for continuous drainingDigital humidity displayMultiple configuration options Attached with wheels for easy movement 
Frigidaire 50-Pint Smart DehumidifierWi-Fi enabledConnects to mobile app and with Alexa or Google AssistantUpto 28 litres in capacityOptions for a drain hose and a removable water tank Hassle free water tank that is located at the front with a splash guard and an easy-carry handle Alert for when the water tank is full 3 fan speeds and custom humidity controlAttached with wheels and side handles for easy movement Easy to clean washable filter
Ivation IVAESDH30P DehumidifierBudget-friendly Suitable for smaller spaces3 size variations with a capacity to cover upto 1,500 sq. feetBuilt-in humidity sensor with a display showing current humidity level, and allows for customization for required humidity levels Options to drain the water through a hose or through the water tank Water tank has a 12.5 litre capacity 24 hour timer, filter alerts, customizable fan speeds, and eco-efficientENERGY STAR Certified2 fan speeds, auto-defrost, and auto re-start 

Mechanical ventilation systems 

One of the primary reasons why air quality deteriorates in a basement is because it is not ventilated well. Installing a mechanical ventilation system would allow for proper air circulation in an efficient manner by bringing in fresh outdoor air into the basement, and creating a way for the stale air to move out. Installing a mechanical ventilation system might turn out to be expensive, but it is an investment that will benefit occupants greatly, especially when the basement is mainly used for storage purposes. 

Budget-friendly mechanical ventilation systems includes setting up of box fans, exhaust fans with a ventilation pipe, or air conditioning. 

Product nameWhy I recommend it
AC Infinity AIRTITAN T8 Crawlspace and basement ventilator fan providing moisture control and efficient ventilationExhaust airflow removes odours and stale air, and reduces humidityProgrammable controller with sensors for automatic airflow adjustments for better humidity and temperature levels Stainless steel structure is resilient to dust and water damage Energy-efficient mode availableLCD screen, smart thermostat and dehumidistat controlCustomizable fan speeds allowing for efficient air flow at lower noise levelsFan speed can be programmed to automatically adjust to surrounding needs Timer allowing functioning of different speeds in different time periodsOther features include alarms, alerts about fan failures, and backup memory
Durablow MFB M2D Air-Out Basement VentilatorFeatures include 2 fans, dehumidistat, frozen temperature protection thermostat, etc. Can be connected to smart devices like Alexa, Google Assistant, and Smart Life APPRemoves excess humidity and increases airflow to reduce condensation and prevent wood rot Prevents the in-flow of radon gas or other harmful pollutantsA control panel to show current levels of humidity and temperature Stainless steel structure creating better resilience to damage due to environmental factors Low-noise levels, if installed properly EVA shock absorption pads to help with noise minimization 
Tjernlund X2D Model Products Xchanger Reversible Basement FansReversible fans for optimal positioning, ensuring efficient air flow and balanced air exchange Dehumidistat controls with on/ off switches and magnetic draft shut-offsDetachable hood for easy installationSimultaneously removes humid air and creates in-flow of fresh air Works well for sealed crawl spaces and garages 3 air flow options Complies with residential ventilation requirements Versatile usage (basements, garage, attics, sheds) Dilutes basement radon levels Requires lesser power in comparison to other ventilations systems

Sealing cracks

Quite often basements have gaps or cracks on their windows, walls, etc. which leads to an increase in humidity levels and allows for the in-flow of other toxic particles (e.g., from the insulation) into the basement air. Sealing these cracks using expanding foam or caulk would be key to maintaining a stable environment in a basement.  

Remove VOC items 

Basements are sometimes used to store painting materials, cleaning agents, lacquers, varnishes, etc. that tend to produce toxic fumes of VOCs. Storing such items in a well-ventilated area such as an outdoor shed or a garage would drastically improve the air quality in a basement. All paints contain VOCs; therefore, it is always best to choose wall paints that contain zero or low amounts of VOCs to reduce and limit exposure.  

Waterproofing basements 

This would allow for the basements to remain dry at all times, especially during rainy weather. This could reduce or resist any water damage to a basement and thus will reduce the moisture and keep away mold and mildew, which could destroy items stored in a garage, especially if they are in cardboard boxes.

Frequently Asked Questions (FAQs): How to improve the air quality in your basement?

How do I measure the air quality in my basement?

Various environmental companies offer services that would measure air quality in your home and basement. The information from these tests could help to form a plan that best suits the needs of the occupants living in the house. Experts from the companies could also help occupants with mitigation strategies to improve and maintain indoor air quality. 

How often should I measure indoor air quality? 

To ensure proper and healthy levels of indoor air quality, it would be suitable to measure them, at least once a year. 

How do I find the right de-humidifier or air purifier for my basement? 

There is a variety in the kind of device you could use to best meet the needs of your house or basement. Enlisting professional help with respect to measuring indoor air quality, could help in identifying the right specifications of the devices required to maintain proper air quality. Types and capacities of the devices needed will depend on the size of the basement, how effectively the space is used, what is stored in the basement, etc., it is important that the devices used to match the needs for the space it is allocated to. 

Does opening my basement windows help with ventilation? 

Opening basement windows do not help with ventilation. If opened, they allow for hot and humid air to enter into the basement and thus increasing indoor humidity. It could also lead to an in-flow of external contaminants, allergens, dirt or debris, etc. that could impair basement air quality. Therefore, it is best to keep basement windows closed. 

Other FAQs about Air Quality that you may be interested in.

Can bad air quality cause a fever?

Can poor air quality affect your eyesight?

Can poor air quality cause nosebleeds?


Environmental Protection Agency (EPA). (n.d.). Health Risk of Radon. United States EPA. 

RTK Environmental Group (RTK). (n.d.). Beware of Basement Air. 

Environmental Protection Agency (EPA). (1991, February). Indoor Air Facts No. 4 Sick Building Syndrome. Revised. Air and Radiation (6609J). Dept. of Research and Development. United States EPA. 

Dyson K. (2021, February 26). How to improve basement air quality. Air Quality & Comfort. Home Air Guides.   

Poslusny C. (2021, October 26). How does indoor air quality impact sleep? MOLEKULE. 

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