Our verdict:
A lack of ventilation and high humidity and moisture levels mean many basements have poor air quality. Mold is undoubtedly the most common reason basement air can be so harmful, yet VOCs and dust can also contribute to and cause problems.
Fortunately, there are lots of ways to improve air quality. Drying out the space with a dehumidifier is super important and using an air purifier to clean the air and eliminate pollutants is also crucial. Sealing any cracks and gaps, plus removing sources of VOCs, such as paint pots, will also help to ensure healthier air is circulating.
Basements are useful spaces for storing items and can even provide extra room for hanging out. Yet when it comes to air quality, they’re often one of the worst areas in your home. Dampness and mold are the major causes of poor air, and we’ll be exploring why that’s the case and looking at some other causes in more detail.
The good news is that improving basement air quality is easily doable, and we’ll provide tips on how you can do just that. For example, simple things include dusting frequently and removing sources of VOCs. We’ll also give you a heads-up about why using a dehumidifier to dry out the space and an air purifier to clean the air will help enormously.
Why Your Basement Might Have Poor Air Quality
There are several reasons why your basement might have poor air quality, so let’s explore these reasons and help you diagnose your main basement problems.
Cause 1: Mold
Basements are especially prone to dampness as they collect and trap moisture more than any other area in your home. And because damp conditions cause mold, your basement is the most likely place mold grows.
Able to thrive and spread easily, mold is the number one cause of poor air quality in basements — and it can also seriously affect your health. The term “sick building syndrome” refers to places where poor air quality spreads. Mold infestations are responsible for approximately 80% of such cases, leading to various health issues, including breathing difficulties and fatigue.
| What does mold look like? Mold can often emit a pungent smell (a bit like dirty socks or wet wood), but if you can’t pick up anything like that, you can test for mold easily by following the steps below: 1. Simply add 1 part bleach to 10 parts water in a glass container. 2. Dip a cotton swab in the mixture and dab this on a suspected area. 3. If the area lightens, then it’s mold. |
Cause 2: Volatile Organic Compounds (VOCs)
VOCs are found in many households and basements are often a prime location. According to the EPA, VOCs are organic compounds that are produced from various solids and liquids. Some of the most common VOC sources include paint, cleaning products and building materials and many people keep such products in their basements.
Breathing in VOCs can cause health problems like eye, nose and throat irritations. And due to the stagnant air typical in basements, the risks of exposing yourself to such toxic chemicals are heightened.
| How to Identify VOCs As you can’t see VOCs, one of the best ways to identify them in your basement is simply to read product labels. For example, formaldehyde is one of the most widely-known VOCs, which should be listed on labels and other useful information about chemical emissions. |
Cause 3: Radon
Radon is a gas that naturally occurs outdoors and is produced from the breakdown of uranium in rocks and soil. Yet radon can find its way inside your home, particularly in houses that are built on soil with uranium deposits.
Radon levels can be highest in basements and crawl spaces and can enter them through cracks in floors and walls. Unfortunately, radon exposure can be a serious health hazard and may increase the risk of lung cancer.
| How to Spot Radon Like with VOCs, you can’t see radon (or smell it). The only way to identify it in your basement is to conduct a test. The EPA advises that you can find many of these test kits online and in home improvement stores. Be sure to look at what we think are the best radon detectors on the market. |
Cause 4: Dust and Dust Mites
Dust is a mixture that includes dirt, hair and dead skin cells and can be found anywhere in your home. However, because there’s often a lack of air circulation in basements, the dust has a greater chance of accumulating in this space.
Similarly, dust mites thrive in areas with high humidity, such as basements and absorb moisture from the air. They can cause various health issues, such as sneezing and watery eyes and exacerbate asthma symptoms.
| What do dust mites look like? Dust is fairly easy to spot and appears like little balls of gray fluff. Yet dust mites are microscopic and can only be seen under a microscope. However, there is a good chance that they might be in your basement because of the high humidity levels. |
If you have a dust mite allergy, you’ll probably experience some of the symptoms mentioned above.
How To Improve the Air in Your Basement
Luckily, there are plenty of effective methods for improving air quality. Be sure to give these a try.
- Use a Dehumidifier to Dry it Out
As most basement problems are caused by dampness and humidity, the first step is to control moisture and dry out the space. By doing so, you’ll also be keeping mold at bay. Using a dehumidifier is one of the best ways to dry out your basement, as it will lower the relative humidity in the air.
To be clear, however, a dehumidifier will not kill mold. What it will do is help to prevent mold and mildew from growing and flourishing.
| Pro tip: Aim for a humidity level between 30-50% for best results. Humidity below 50% will significantly help prevent mold from surviving in your basement. |
- Use Mechanical Ventilation Systems
Another major reason basement air quality can be so poor is the lack of ventilation. In such an enclosed space, the air becomes trapped and doesn’t get recycled with clean air from outside.
Air conditioning is an effective method, yet it can be pricey to have this professionally installed if you don’t already have an HVAC system. Fans are a relatively cheap way of circulating the air, but you should be able to find a good one for less than $100.
| Pro tip: If you do have an AC system running in the upper part of your house, leaving the door open means that some of the conditioned air should also reach your basement. |
- Close Windows
Ordinarily, opening windows is a great way to increase ventilation. Basements, however, are different from the other rooms in your house due to the higher humidity levels. This is especially true during the warmer summer when humidity increases even more.
Opening basement windows can cause the humidity to rise and may also draw in allergen particles from the outside, so your best bet is to keep them closed.
| Pro tip: You could try opening a window in the fall and spring months when pollen and allergen particles are generally lower. |
- Seal All Cracks and Gaps
Following from tip 4, if you’ve got any cracks or gaps around walls or windows, this can let in outdoor air and potentially increase humidity levels. Be sure to check for any cracks or gaps and seal them up as soon as possible.
| Pro tip: The best sealants for problem areas are caulk and expanding foam. |
- Remove Sources of VOCs
As we’ve already talked about, volatile organic compounds coupled with poor ventilation can seriously affect the air quality in your basement. A simple way to reduce the chances of inhaling the toxic fumes is to store VOC products elsewhere, specifically out of the house. If possible, place pots of paint, solvents and any other VOC contributors in a garage or outdoor shed.
| Pro tip: If you’re particularly concerned about VOCs, you can buy an air quality monitor to measure the level of VOCs in the air. |
- Clean Regularly
Finally and clean your basement regularly to keep dust at bay. Dusting frequently means that those harmful dust mites will be less likely to make a home in your basement. This includes everything from boxes to gym equipment. Using a microfiber cloth or a wet washcloth is your best tool, as these will trap and lock dust rather than disperse it back into the air.
| Pro tip: If you have carpets in the basement, vacuuming with a device with a HEPA filter will further help clear away any dust mites. |
- Run an Air Purifier
Controlling humidity and moisture is crucial, but to improve the air in your basement, you need to clean it. This is where air purifiers come in, as they’re specifically designed to remove harmful contaminants, such as mold spores and bacteria.
However, there are many purifiers on the market, so choosing one with certain features is important. These include a HEPA filter to remove the most toxic particles and an activated carbon/charcoal filter to eliminate VOCs.
| Pro tip: Be sure to opt for a device that’s the right size for your basement. Most basements are big, so if the purifier is too small, it will struggle to clean the air effectively. For a more detailed guide on all the things to look out for, check out what we think are the best air purifiers for basements. |
The Best Air Purifiers for Your Basement
We perform air-cleaning performance experiments for all of the air purifiers we review here at HouseFresh. We fill our home lab with incense smoke and track how fast an air purifier can clean, so we can confidently present you with our top 3 units for basements as of 2023.
Final Thoughts
While basements can be annoyingly susceptible to poor air quality, that doesn’t mean you have to put up with it. Investing in a dehumidifier will help to keep dampness at bay, and prevent mold and mildew from growing. Similarly, using an air purifier will remove those harmful airborne contaminants.
Ventilating the space is equally vital and you can get the air circulating by simply using a fan. Also, be sure to clean and dust regularly and watch out for any cracks or gaps that can let in humid air from the outside.
Sources
American Lung Association. (2022). Dust Mites. lung.org
Ashton, D. (2023). HouseFresh. 4 Best Air Purifiers for Basements. housefresh.com
Ashton, D. (2022). HouseFresh. How To Ventilate a Basement. housefresh.com
Ashton, D. (2022). HouseFresh. Do I Need A Dehumidifier In My Basement? housefresh.com
Boggs, D. (2021). Boggs Inspection Services. How to Improve Air Quality in the Basement. boggsinspect.com
Cookson, M. (2022). HouseFresh. Will a Dehumidifier Kill Mold? housefresh.com
Conditioned Air Solutions. (2023). Improving Air Quality in Your Home’s Basement. conditionedairsolutions.com
Dyson, K. (2021). Home Air Guides. How to Improve Basement Air Quality. homeairguides.com
Environmental Protection Agency. (2022). Volatile Organic Compounds’ Impact on Indoor Air Quality. epa.gov
Environmental Protection Agency. (2022). Find a Radon Test Kit or Measurement and Mitigation Professional. epa.gov
Simon, S. (2019). American Cancer Society. How to Test Your Home for Radon. cancer.org
Stellate. (2020). Four Ways to Identify Volatile Organic Compounds (VOC) Pollutants in Your Home. stellatecorp.com
Wallender, L. (2022). The Spruce. How to Identify and Treat Mold in Your Basement. the spruce.com
Werner, A. (2021). Real Seal. Tips for Controlling Basement Dust Mites. therealsealllc.com
Last update on 2023-03-22 / Affiliate links / Images from Amazon Product Advertising API