Basements can be such fun they provide great recreational, living or just storage areas. The air quality is usually an issue because ventilation is often not as good as the rest of the home. So a basement air purifier can be a very useful addition to improve air quality.
The best air purifier for a basement is the Coway 400S, it has a highly specified filter for removing ultrafine particles and a very high airflow at a lower noise level than any other consumer air purifier. So it is ideally suited to a basement. The Sharp FX-J80U is a great alternative.
Basements are often large and poorly ventilated with stagnant air in which chemicals and particles can accumulate. So let’s consider the 2 features of basements that determine the choice of “best air purifier for basements”-
1) LARGE SIZE-so the main criteria for servicing a basement is the AIRFLOW the air purifier can achieve at a noise that you find tolerable
Let me explain-
An air purifier has a fan which sucks in air and then pushes it through the filter where the airborne particles are then trapped. The trapped particles are permanently removed from the air so improving indoor air quality. So the most important features of an air purifier are the quality of the filter and the amount of air that the fan is pushing through it every minute.
True HEPA Filters-are very similar in their effectiveness in removing particles-so important but not the deciding factor
The most damaging aspect of poor quality air on health is usually due to the effect of particles. So a crucial feature of any air purifier is the particle filter as this determines the highest purification that the air purifier can achieve. HEPA filtration is extremely efficient and now effectively the minimum standard for a filter. Therefore, it is important to have a true HEPA filter-this will effectively remove almost all airborne particles. Beware of “HEPA like”, “HEPA style” “99% HEPA”… terms describing the filter like this means it is not a true HEPA filter.
The HEPA specification is based on the ability to remove fine particles 0.1um-10um. The standard specifies that the filter must remove 99.97% of particles of 0.3um in diameter.
So ultrafine airborne particles which are less than 0.1um and so not explicitly covered in the HEPA specification but they are also major health concern. These particles have been found in the bloodstreams of humans and are thought to be very important in the damage to human health from pollution. Some air purifier manufacturers are now specifying the range of ultrafine particles that their HEPA filter will remove. My top pick, the Coway 400S is certified to remove 99.95% particles down to 0.01um.
This is the new filter specification that separates this air purifier from all others on the market except the iQair HealthPro Plus.
So having established that a HEPA air purifier is essential but does not decide which air cleaner to choose amongst the 100 or more models with a HEPA filter, let’s now turn to the factor which does decide-airflow.
Airflow-the deciding factor in choosing the best air purifier for a basement
The amount of air purified per minute needs to be higher for larger spaces and basements often contain larger spaces that need air purification. So in choosing the best air purifier for basements the airflow that the air purifier can achieve at reasonable noise levels is extremely important.
There are manufacturer’s claims then repeated in internet reviews that consumer air purifiers (less than $1000) can service an area larger than 650sq ft. It is true that you can simply switch any air purifier on in a big room and it will slightly purify the air. However, the air purification will be substandard, you may only get a 20 or 30% particle reduction rather than the minimum EPA stipulated 80% reduction. Unfortunately, this may then lead to lower quality health outcomes for you and your family, as outlined in this article.
There is no consumer air purifier on the market that can purify the air of a larger space than 650 sq ft (assuming 8 ft ceilings) and meet the EPA’s minimum standard for air purification.
The EPA’s minimum standard for purifying air is that the air purifier should provide 4.9 air changes per hour. An air change is when a volume of air equal to the volume of the room has gone through the air purifier once. So at a minimum all the air in your room should go through the air purifier 4.9 times every hour. This will reduce the particle count in the air by 80%.
The only way of purifying the air in an area greater than 650 sq ft is to have multiple air purifiers.
Do not judge an air purifier by its looks some of the best looking air purifiers have surprisingly low airflows.
Also, please do not judge by how expensive an air purifier is. Some very expensive air purifiers have no clean air delivery rate (CADR) specified at all. This may make you wonder why a manufacturer would not specify the CADR, you may think that they would do so if the CADR was good. It also makes it impossible for you to size the air purifier according to the EPA’s room sizing guidance.
My advice is if the air purifier manufacturer will not give you the CADR at the fan rate where the noise is slightly below 50db then do not buy that air cleaner. The reason is that if you buy one for its highest flow rate which is often noisier than 50db, you are likely to switch it down to a quieter fan setting.
On this quieter setting, you will get inadequate air purifircation as you sized the air purifier for your room using the highest setting, You may only achieve a 50% reduction in particle count. The inadequate reduction in particle count will mean that your health will deteriorate at a faster rate, and this will occur without you realising it until something goes wrong.
If you do measure the particle count with a meter as I encourage everyone to do, you will realise that the reduction is inadequate and that you need to buy another different air purifier.
So please before you buy any air purifier check that the manufacturer gives you a CADR at a noise level less than 50db, if not, do not buy that air purifier.
So the new airflow technology that separates the Coway 400S from other air purifiers is the design with one set of filters on either side of the machine. This allows a larger filter surface area, less resistance to airflow and so a larger airflow for a lower noise.
Particles are not the only airborne pollutant affecting basements, chemicals can also build up in the air a problem to which I now turn.
2) STAGNANT AIR in the BASEMENT Which Chemicals Can Build UP-so an activated carbon filter is needed in a basement air purifier
Many basements have reduced or poor ventilation compared to the rest of the home and so gaseous pollutants such as chemicals can build up in the air. This often gives a musty smell. Fortunately, there is an easy way to remove most of these, by adsorption by activated carbon. So an air purifier for a basement should have as good a carbon filter as possible.
Most modern air purifiers have activated carbon filters the best ones have granular activated charcoal filters. Carbon provide a very very large surface area in cracks inside the granules. The granules can be seen in this filter-
For other carbon filters, a thin layer of carbon is applied to the surface of the filter. Activated carbon filters remove volatile organic compounds by adsorption. The weight of carbon determining their capacity to remove chemicals. The carbon filters are sometimes impregnated with chemicals to use chemisorption as well to remove chemicals. Chemisorption works by a compound in the filter forming a molecular bond with the air pollutant. The chemical filters make the air safer and also lessen any odors. The Coway 400S has 2 granular carbon filters.
As with particles the chemicals stuck to the filter are thrown away when the old filter is discarded and a replacement filter installed in the air purifier. In this way the chemicals are permanently removed from the basement.
Please note a carbon filter can remove many things but not radio-isotopes. So radon levels which can be high in some homes and are linked to lung cancer will not be reduced by an air purifier.
The Top Air Purifiers for Basements
The choices here represent the best choices of air purifiers from all established manufactures on the market who would give me the noise levels at their machine’s various air flows. This information is needed so that I do not recommend an air purifier that is too noisy for you. Also, as outlined above only air purifiers with smart control were considered. as for health reasons an air purifier needs to come on 30 minutes at least before you step into the room as explained here. So a schedule for it switching on and off needs to be programmable.
My top pick for a basement because of its superb filter and high airflow a the lowest possible noise levels for the airflow.
|HEPA filter||HEPA specified to remove 99.8% of ultrafine particles down to a size of 0.01um|
|Carbon filter amount of carbon (lb)||1.5 lb so more than most other air purifiers|
|Filter Change HEPA (Particles)||12 months|
|Filter Change Carbon (Chemicals)||12 months|
|CADR at =<50db (CADR on Maximum)|
|Maximum Room Size (Noise less than 50db*)||450 sq ft|
|Maximum Room Size (On noisiest setting)||640 sq ft|
|Smart Control||Yes phone app|
|Dimensions “H x “W x D”||22.8 x 14.8 x 14.8|
|Annual Running Cost Electricity ($)||$40|
|Annual Running Cost Filters ($)||$120|
|Total Annual Running Cost ($)||$160|
All the above are approximate and assume running the air purifier for 12 hours per day on the highest setting that keeps the noise below the level specified in db in the table. This is less than or equal to 50db in normal daytime use and 35db for bedrooms.
*Most people will not wish to have the air purifier on a setting louder than about 35db for sleeping in a bedroom-you may wish to have a quieter setting than 35db this is just a ballpark estimate for most people. On the other hand, if your room layout allows you to be much further than 6 feet from the air purifier you may find the noise this machine makes at top speed is alright. The calculations for room size assume that you have 8 foot ceilings and 5 air changes per hour.
Never run an air purifier on auto mode using the inbuilt sensor. These cannot detect ultrafine particles which are damaging to human health, please see this article- How to test the air quality in your home.
The Sharp FX-J80U is also an excellent choice for an air purifier for a basement.
|Carbon filter amount of carbon||Carbon granules about 1lb|
|Filter Change HEPA (Particles)||24 months “maximum life”|
|Filter Change Carbon (Chemicals)||24 months “maximum life”|
|CADR at =<50db (CADR on Maximum)||321 cfm|
|Maximum Room Size (Noise less than 50db*)||494 sq ft|
|Maximum Room Size (On noisiest setting)||494 sq ft|
|Smart Control||Yes phone app, Alexa or smart home system with a smart plug|
|Dimensions “H x “W x D”||28.7 x 16.4 x 11.5 inches|
|Annual Running Cost Electricity||$42|
|Annual Running Cost Filters||$90|
|Total Annual Running Cost||$130|
This air purifier also has a plasmacluster ionizer but you may wish to disable it-please see this article.
For an explanation of the basis of the calculations please see grey block above.
Multiple Levoit 200S each only $80 and 3 of these could cover an area of 540 sq ft
This air purifier has the highest airflow per dollar of any air purifier on the market from a well known manufacturer, approximately double that of other air purifiers.
There is always an argument in a large room for rather than having one big air purifier at one end of the room having 2 smaller ones at either end of the room. This is because the mixing of air in a room is not perfect, so with one large air purifier down one end of the room the air at the other end will not get as much purification.
|HEPA filter||HEPA 13 filter|
|Carbon filter amount of carbon||Small amount of carbon incorporated into main filter 0.1 lb|
|Filter Change HEPA (Particles)||7 months|
|Filter Change Carbon (Chemicals)||7 months|
|CADR at =<50db (CADR on Maximum)||118 cfm (118 cfm)|
|Maximum Room Size (Noise less than 50db*)||183 sq ft|
|Maximum Room Size (On noisiest setting)||183 sq ft|
|Smart Control||Smart Phone App/Alexa/Google Home|
|Dimensions “H x “W x D”||12.6 x 8.1 x 8.1inches|
|Annual Running Cost Electricity||$24|
|Annual Running Cost Filters||$45|
|Total Annual Running Cost||$70|
For an explanation of the basis of the calculations please see grey block above.
iQair HealthPro Plus-Best Air Purifier on the Market but Not so Suitable For Large Rooms
The above air purifiers are extremely well suited to basements. However, the best air purifier on the market is the IQ air HealthPro plus. This is not so well suited to basements because it will only service as an area of 262 ft.² at a noise of 50 dB. I find constant noises above this too intrusive, you may of course be different or have a long thin basement where the air purifier will be at the other end of the room, in which case the HealthPro plus would be an excellent choice for your basement. I have written an article about it here.
How Long Should I Run an Air Purifier for in a Basement?
As a general rule you should run the air purifier for 30-45 minutes before going into the basement and then continuously whilst you are in the basement. This is the standard technique for using an air purifier in any room, you may be interested in this article which goes into more detail about how to use an air purifier.
Depending on your basement, it may also be good to clean the air for 2 hours twice a week to prevent the build up of chemicals and reduce smells. This schedule could be programmed into the air purifier.
All Other Air Purification Technologies Have Problems
HEPA air purification with an activated carbon filter and a fan to push air through the filters is the standard method of air purification. There are other techniques but they have problems compared to this standard-
- PECO eg the Molekule-not effective enough at reducing particles, see Wirecutter YouTube video.
- UV light-ineffective at dealing with some microorganisms (please see this article), potential for eye damage and ozone production depending on technology used. They do not remove particles.
- Ionising air purifiers give particles an electric charge which makes them stick to things. They can reduce particles count in the air but increase the depositing of particles in your lungs. This technology does not deal with chemicals. Further details of how ionizing air purifiers work can be found here.
- PCO-photocatalytic oxidation-uses UV light and titanium oxide to change particles. It does not remove airborne particles such as mold spores, allergen, house dust mite, pet dander, house dust particles, or cigarette smoke particles. It can produce formaldehyde which is known to be carcinogenic.
- Ozone generators-damaging for health in any case and like PCO and UV light do not remove particles. in fact in a basement it is even more important to have an ozone free air purifier as ventilation is often poor.
Other Important Ways to Improve Basement Air Quality
- Install some form of ventilation and periodically ventilate the basement. This is the only way to reduce the concentration of radio-isotopes eg Radon. For Radon other measures also need to be taken such as sealing the basement.
- Use a robotic HEPA vacuum cleaner to clean the floor of dust regularly.
- Regularly dust the basement, ideally just before vacuuming.
The best air purifier for a basement is the Coway 400S it has the highest airflow delivery for the lowest noise of any consumer air purifier. The Sharp FX-J80U would also be an excellent choice there is little to choose between these two air purifiers. Either will improve the air quality in your basement so that your health does not suffer. They will also help get rid of that basement smell if there is one.
You will see many great looking air purifiers with all sorts of technologies, but they will not in reality be as good as these 2 air purifiers. Many will not even be even half as good even although they are more expensive and look wonderful. So if you decide to buy anything else tread carerfully, there are plenty of machines out there with hidden drawbacks.
If you cannot really afford these machines your choice is easy, the Levoit 200S delivers more cubic feet of air per minute per dollar than any other machine from a reputable manufacturer. It delivers twice as much air per dollar as most other machines. It will only serve an area of 183 sq ft so if your basement is larger you may need 2 or more of these air purifiers
How air purifiers work-a fascinating article explaining the mechanisms in an air purifier that make them work
The health effects of particles in the air-a very important article to read about the effect of particles in the air on our health with some surprising facts