Best HEPA Air Purifiers – ( Top 10 Roundup )

  • Best HEPA Air Purifiers
  • Rating: 5
  • Reviewed by:
  • On April 10, 2017
  • Last modified:April 11, 2017

Review Summary:

Take a look at our Top 10 Air Purifiers reviews for 2017, before you buy.

Trying to find ways breathe easier? For some people doing a simple thing like stopping to take a deep breath can be a difficult thing due to allergies, asthma or polluted air. Air Purifiers can be a potential solution for those seeking ways to clear their home of contaminates such as dust, mold, pet dander, or even second-hand cigarette smoke. Wether you are looking for an air purifier to help ease the symptoms from allergies or are simply looking for a way to have cleaner air in your home to prevent future illnesses, choosing the right air purifier can become a daunting task.

I put together a list of the top ten air purifiers to help make the choice a little bit easier. I will be reviewing air purifiers for all sizes of rooms, and will consider the cost, size, cleaning ability, and build of each. Read on to our reviews of each air purifier to consider which option works best for you.

 What is an Air purifier?

An air purifier, which also may be known as an air cleaner, is an appliance that is designed in order to remove contaminates from the air in a space, or room. These contaminates, such as dust, pollen, mold, pet dander or even second-hand smoke often cause asthma or allergy symptoms in many people. Many turn to air purifiers to try to clean the air in their house and relieve their allergy symptoms.  Air purifiers are made in a multiple of sizes and clean the air in small or large spaces depending on the model.

HEPA filters are well known to be one of the best filtration systems when looking to remove contaminates from air in your space. HEPA filters remove 99.97% of particles down to .03 micrometer in size. This is a very effective method of removing pollutants from your home. Many Air Purifiers will include other filtration methods in addition to the HEPA filter to optimize air cleaning abilities. Some of the other methods that are commonly used are the addition of a carbon filter, Ionization, UV-light, or perhaps even ozone generators.

The Cost of Air Purifiers

The cost of air purifiers can vary greatly. In my list I have included air purifiers that range from the  highest quality as well as the best performing budget friendly options. Many air purifiers can be a bit of investment. Many people find that the more expensive models are worth the cost. Overall, theses high quality and high performing air purifiers seem to work better, and remove more contaminates from homes. If you able to make this type investment, your health may thank you for it.

Conversely, there are also plenty of budget friendly models available as well.  You should not immediately dismiss an air purifier because of its low price. Many of the smaller, or less expensive models can still provide many benefits to cleaning the air in your home. Plenty of reviewers have found cost-friendly air purifiers have worked wonders for them

Air Purifier Reviews & Scores 2017– The Goal of Our Report

In order to get the best information on air purifiers, I will be rounding up the bestsellers and looking at reviews and ratings to find the best available air purifiers. I will be looking at the quality of construction, the Energy Star ranking, , consumer reviews, CADR ratings, filtration methods, and Sq. Ft. coverage. I will include all the air purifiers from a number of categories that stand out as the best. I will include high performers as well as economical choices. My goal is to make a list of top performing air purifiers to help make your buying choice easier.

Product NameFilter typeRoom SizeFilter LifeDimensionsWeightCADR 
IQAir HealthPro Plus Air PurifierTrue-HEPA

Up to 1125 Sq Ft. 4years
16 mths
16" x 15" x 28" 35 lbs Check Price
Alen BreatheSmart Customizable Air Purifier with Hepa-Pure FilterHEPA- 4 options
Up to 1100 Sq Ft. 8-9 Months26.75" x 17.75" x 10"21 lbs Check Price
Alen Paralda HEPA Dual Airflow Tower Air PurifierHEPA
Up to 500 Sq Ft. 6 Months28" x 7" x 11"15 lbs Check Price
GermGuardian AC4900CA 3-in-1 Air Cleaning SystemHEPA
Up to 156 Sq Ft.6-8 months8.875" x 7.125" x 21.75"9.6 lbs101 + Check Price
Honeywell HHT-011 HEPA Clean Compact Air PurifierHEPA
up to 85 Sq Ft.permanent14" x 6.50" x 10.75" i1 lbs Smoke: 55
Dust: 55
Pollen: 65
Check Price
Honeywell 50250HEPA
carbon activated
up to 390 Sq. Ft3-5 years18.03" x 18.03"x 19.57 "21 lbs250 Check Price
Coway AP-1512HH Mighty Air PurifierHEPA
Up to 365 sq, Ft.Carbon- 6mths
Hepa- 12- mths
16.8" x 18.3" x 9.6"12.3 lbsSmoke- 233 Dust- 246 Pollen-, 240 Check Price
Rabbit Air BioGS 2.0 Ultra Quiet HEPA Air PurifierHEPA
Up to 625 Sq Ft3 years16.6" x 9.8" x 22.2"22 lbsPollen-162 Dust-149 Smoke-135
Check Price
Winix 5500-2 Air Purifier HEPA
Plasma Wave
Up to 360 Sq Ft.1 year15" x 8.2" x 23.6"15.4 lbsPollen- 246 Dust- 243 Smoke-232 Check Price
Winix WAC9500 Ultimate Pet True HEPA Air Cleaner with PlasmaWave TechnologyHepa
Plasma Wave
up to 283 Sq. Ft. 1 year16.5" x 8.9" x 21.9" 24.3 lbsPollen-194
Tobacco Smoke- 183
Check Price

IQAir HealthPro Plus Review – Best Commercial Grade Air Purifier

  • Price: $899
  • Room size: Large to extra large
  • Filters: Pre-filter, HEPA, V5-cell

The first thing that comes to mind with the IQ Air Health Pro Air Purifier is “you get what you pay for.” This is a pricey unit which may be a deterrent for many people, but if you are looking for the ultimate air cleaning machine to reduce allergy and asthma symptoms, then this would be the one to get. This commercial grade machine boasts that it is able to remove 99.5% of all particles in the air all the way down to 0.002 microns, which is the size of the smallest viruses and bacteria. It consistently ranks as one of the top air cleaners, producing the cleanest and most allergy-free environments for air purifiers. 

The IQ Air Purifiers earns its place as number one on my top ten place because of its high performance and overall reputation. It remains a constant customer favorite and produces the most favorable reviews for sufferers of allergies and asthma. This is the machine for serious air quality improvement!

This machine uses three filters, which need to be replace on a rotation schedule. The rotation schedule helps reduce the burden of replacing the somewhat costly air filters. Again, with this machine, you have to keep in mind “You get what you pay for!” The first filter is  the pre-filter, which will be removing most of the particles from the air. After this the air is filtered through a much more compact charcoal cell filter to remove odors. The charcoal filter does a great job in removing odors and greatly improves air freshness. The third filter is a True-Hepa pleated filter to remove all remaining particles. When it is all said and done this air purifier claims to be able to remove 99.5% of all particles down to 0.003 microns in size. In comparison most other machines claim to be able to remove 99% of all particles down to 0.3 microns in size. This is a notable difference! It has to be noted that this machine is even being used in Hong Kong hospitals around SARS patients. 

As I mentioned before, the IQAir HealthPro Plus is an expensive investment. The initial cost of the machine runs $899. The machines comes with the initial filters but as time goes on they will eventually need to be replaced as with any air purifier. The replacement filters are as follows: the Pre-Max filter should last about 16 months , The HyperHepa filter should last 4 years , and lastly the V5 cell filter has a lifespan of around 2 years. The replacement cost of the filters is also a bit high and should be budgeted for accordingly. The lifespan of the filters may vary according to use, but overall these filters seem to last longer in comparison to other machines.

The noise level on this machine is actually pretty low in comparison to other high performing air purifiers, but still on its higher settings it can run a bit loud. It would not be ideal at theses setting for use in a bedroom at night. However at the lower settings the machine has a nice background hum that isn’t bothersome.

As far as the build goes, this unit is a bit of a beast. It measures 16 x 15 x 28 inches and weighs 35 pounds. It is well constructed and designed for quick and easy filter cleaning and replacement. The display will also show the stage of cleanliness the filters are currently at.

One thing that this machine does NOT have that I would like to see added is an auto feature, that would automatically detect air quality and adjust itself accordingly. Other than, this air purifier does its job and does it well.

IQAir was chosen by Consumer’s Digest as a Best Buy for several years including 2004, 2007, 2011, and 2014.


  • High performance
  • Immediate results
  • Easy to replace filters
  • 6 speed settings
  • Energy Efficient
  • Filters bacteria and viruses
  • Expensive
  • Costly price for filter replacement
  • May be too loud for a bedroom on higher speeds
  • Boxy and unattractive
Lowest Price Found Here @ Amazon

Alen BreatheSmart Customizable Review -Best Air Purifier for Large Spaces

  • Price: around $600
  • Room size: Large to extra large
  • Filters: HEPA, Ionizer,

This Alen Model is a great choice for purifying the air in large or open spaces. It is effective for a space up to a very impressive 1100 Sq. Ft. It runs quietly, weighs only 21 pounds, and has an unobtrusive size. One of my favorite features of the Alen BreatheSmart Air Purifier is it’s smart sensors, which automatically will detect the air quality in your room. While it is in Auto Mode this machine will automatically adjust its cleaning power to the air quality. It will work harder when high pollutants are detected and run lower when simply maintaining the pure air quality of a room.

The Alen BreatheSmart air purifier also boasts of a CADR of 300. At the higher end of CADR measurements for air purifiers, this unit will deliver fresh air at a quick rate.  This high performing air purifier also runs quietly with its use of WhisperMax technology which utilizes pink noise to remove irritating sounds. Many reviewers noted that it the machine did not emit any annoying noise, and worked at a background or “white noise” level.


This model is also customizable in both color choice and HEPA filter choice. With fourteen color choices available this air purifier is both attractive and desirable for your home. There are four HEPA filter options to choose from as well: HEPA Pure- great for dust and allergens, HEPA-Silver- to remove bacteria and germs, HEPA-fresh Plus- great for chemicals and VOCs, HEPA-odor cell-for the removal of smoke and other strong odors..




This air purifier also purifies the air with the use of an ionizer, which enhances its ability for the freshest air. Additional features on this machine are a timer, child lock, filter life indicator, air quality indicator and a lifetime warranty. It is also Energy Star Certified.

Overall I was very impressed with this air purifier. It is considered one of the best performers and is able to improve the air quality of a room in just two hours. With outstanding reviews, a reasonable cost, high quality construction, low noise pollution and multiple additional features the Alen BreatheSmart Air Purifier makes the top of our top ten list.

  • High performance
  • High CADR rating
  • Energy Star Certified
  • Color options
  • Filter Options
  • Automatic Air quality Mode
  • works in large spaces up to 1100 sq. ft
  • child lock
  • higher priced model
  • frequent filter replacements
  • use of an ionizer is sometimes unpopular
Lowest Price Found Here @ Amazon

Alen Paralda HEPA Dual Airflow Tower Review – Best Tower Air Filter

  • Price: mid priced around $300
  • Room size: Medium to large
  • Filters: HEPA-silver, ionizer



Much like the Alen BreatheSmart, the Alen Paralda is a high performing and outstanding air purifier. This model comes in a slim and attractive tower construction. It is able to cover up any room or office space up to 500 sq ft.  It is convenient, can be placed in an out-of-the-way location and is very easy to use.

Probably my favorite feature of this air purifier is that it uses Alen’s HEPA-silver filter, which is great for cleaning the air including germs and bacteria. Not all air purifiers are able to clean the air to this level, and to find a machine that can do it and at an economical price was a nice plus.

This model runs at $299, which makes it a budget friendly option for a smaller space. While it wont be as effective for a larger room, if you only want to clean the air in an office space, bedroom or other closed smaller space this machine could be a great option.



The Paralada model has a  unique dual sided air venting system.  It will pull the air from the room into the back intake vents and then easily and quickly release the filtered air throughout the room efficiently via the side vents. It truly has a innovative design. Changing the filters is quick and easy. It runs quietly, and simply works great. Many reviewers remark about the improvement of their breathing and reduction of their allergy symptoms after using this small machine.

One of the frequent complaints about this air purifier is that it runs noisy on its higher speeds. This is just something you might want to keep in mind if you are looking for a machine to be placed in your room while you sleep. The lower speeds run quieter and it may be an option to keep the machine on one of these lower levels at night, if you have it in a bedroom, and think the noise would bother you.

Like the BreatheSmart model, the Paralda also uses an ionizer to charge the contaminates in the air, making them easier to stick together and then be filtered out through the HEPA filter. The ionizer is well known among air purifier companies to enhance performance.

This model also comes with Alen’s unique limited lifetime warranty, and is Energy Star certified. Additional features include a LCD display screen , and a hidden cord space.

  • High performance
  • Energy Star Certified
  • Innovative design
  • Tower design
  • Easy to change filters
  • Filters bacteria and germs
  • Higher speeds can be noisy.
  • Only one filter option in comparison to Alen’s BreatheSmart Model
  • Frequent filter replacements
  • Use of Ionizer can be unpopular
Lowest Price Found Here @ Amazon

Winix 5500-2 Review – Best Efficiency Air Purifier at Affordable Price

  • Price: Affordable -around $150
  • CADR: Dust-243; Pollen-246; Tobacco Smoke- 232
  • Room size: small to medium
  • Filters: True- Hepa, Activated Carbon, Plasma-Wave Technology

Another option in affordable and effective air purifiers is the Winix 5500-2. It has a three stage filtration system that eliminates dust, pollen, pet dander and other pollutants, as well eliminating odors and destroying bacteria and germs. This machine can generally be found for around $150, which is very reasonable for its level of quality and efficiency.

The Winix5500-2 will cover up to 360 sq feet which makes it a great choice for a small to medium sized room. It also runs quieter than many other machines. One of the best things about this air purifier is that it can boast of a good CADR rating in the 240 range, delivering clean air at a good rate, while it remains at an affordable price.

It uses a True HEPA filter, an activated Carbon filter for odors and Plasma Wave Technology to eliminate bacteria and germs. The first filter is an activated carbon filter which will rid the air of unpleasant odors. This filter is washable, giving it a longer life.   The HEPA filter leaves the air clean and fresh by eliminating 99.97% of particles. This filter only needs to be changed out about once a year.  The last cleaning stage is the Plasma Wave Technology which utilizes both positively and negatively charged ions to neutralize viruses and and bacteria that are in the air. The ions combine with water vapor to create a substance known as Hydroxyls. Winix claims that their  patented method will reduce harmful germs, viruses and bacteria without creating any harmful ozone.

Other features include a remote control and auto-sense mode, and filter change indicator. The auto sense mode will automatically adjust the speed of the machine to the air quality level.


  • 3 stages filtration including HEPA, Charcoal and Plasma Wave
  • Removes pollutant, odors, germs and bacteria
  • Runs quietly
  • Affordable
  • Energy Star Certified
  • Washable pre-filter
  • Auto-mode
  • Will not work for large spaces
  • Not appropriate for heavy odors


Lowest Price Found Here @ Amazon


GermGuardian AC4900CA 3-in-1 Air Cleaning System Review -Most Economical

  • Price: Under $100
  • CADR: 100+
  • Room Size: Small
  • Filters:Charcoal, HEPA, UV-C

If you are looking for a good quality air purifier for a small space that won’t break the bank, then the Germ Guardian AC4900CA 3-in-1 Air Cleaning System might be the machine for you.

Priced under $100 this air purifier’s is a economical choice while its  HEPA filter still ranks above average in its cleaning ability. Even though its a lower priced machine, the air purifier is still able to provide great cleaning ability of pollutants, odors and germs with its additional filters.

It utilizes three filters for cleaning the air. The True Hepa filter will capture 99.97% of dust, mold, mildew, pollen and pet dander. It also uses a charcoal filter to remove unwanted odors. Lastly this machine has UV-C light technology to kill bacteria, germs, viruses and even mold spores.

This machine has three speeds and on the lowest speed it runs quietly enough to sleep with while its on. It’s tower design, with a 22 inch height, fits neatly into most spaces. Overall I think the design is quite stylish, and it is unobtrusive in any environment.

The Filter will need to be replaced about every 6-9 months, depending on use.

  • 3 stages filtration including HEPA, Charcoal and UV-C
  • Removes pollutant, odors, germs and bacteria
  • Runs VERY quiet
  • Affordable
  • Energy Star Certified
  • Only one filter to replace
  • Not efficient for medium or large spaces
  • Not appropriate for heavy odors
  • Some complaints of the machine having a bad smell
Lowest Price Found Here @ Amazon

Honeywell HHT-011 HEPA Clean Compact Review– Best Compact Air Purifier

  • Price: Very affordable around $50
  • Room size: Small
  • Filter Types: Pre-filter, HEPA, Ionizer
  • CADR: Tobacco Smoke: 55 Dust: 55 Pollen: 65

If you are looking for an air purifier that is compact, will clean the air in a small space, and is affordable, the HoneyWell  HHT-011 could very well be an option for you. With overall good customer reviews and a price of under $50, the HoneyWell stands out as an economical choice. Small and lightweight, this machine will fit easily into most areas and will work quietly to keep a small space clean of harmful air particles.

This Honeywell unit has a three-filtration system to produce cleaner air. In the first stage air enters a washable pre-filter to catch the largest airborne particles. The second stage forces the air through the HEPA-type filter to catch up to 95% of particles such as dust, pollen, pet dander, and smoke. Lastly this machine has an ionizer to freshen the air even further. The HEPA filter on this machine is permanent, which eliminates the need of ever having to buy additional filters.

A washable pre-filter conserves your expense considerably over time.

Honeywell is a prominent brand name on the air cleansers area, as well as HHT-011 is a representative version situated in small working area with a relatively economical price. You can discover even more Honeywell air cleanser examines information below.

  • Very compact
  • Very affordable
  • Good for a small space
  • Energy Star rated
  • Three stage filtration
  • Will not work for medium or large spaces
  • Not recommended for heavy odors or smoke
  • Overall a short lifespan on this unit
Lowest Price Found Here @ Amazon

Rabbit Air BioGS 2.0 Ultra Quiet Review

  • CADR: Pollen-162 Dust-149 Tobacco Smoke -135
  • Price: Mid-priced unit under $400
  • Room Size: Medium to Large
  • Filters: Pre-filter, HEPA, Carbon, Negative Ion Generator

The Rabbit Air BioGs 2.0 air purifier has earned a reputation for running both quietly and effectively.  It is able to clean the air in a space up to 550 sq. ft. twice in a hour. While this is not the ideal machine for a very large room or open space, it is very effective for a medium size room. This machine has fantastic user reviews, with many reviewers claiming their allergy symptoms have been greatly reduced after using this air purifier.

The pre-filter on this machine is washable, extending its life, while the HEPA filter can be vacuumed out periodically before it needs to be replaced. The HEPA filter has a  lifespan of approximately 3 years, making it one the longer lasting filters available. The HEPA filter has been designed and built in such a way that allergens and bacteria will not build up on the filter and reduce efficiency. It is also a nice feature to not to have constantly change out costly filters on air purifiers! The activated carbon filter will filter out offensive odors, leaving a fresh air environment.  Lastly this machine also has an optional negative ion generator to further freshen the air. The Rabbit company says that their   BioGs 2.0 model emits zero ozone with the negative ion generator turned on or off.

Other features of this machine include an auto sense mode, 24/7 customer support, a filter life indicator, five speeds and a remote.

  • Medium  spaces
  • five speeds
  • Washable pre-filter
  • Economical long lasting HEPA filter
  • Energy Star Certified
  • Runs quiet
  • Auto-mode
  • Not good for heavy odors or smoke
  • Not good for very large spaces
  • A bit on the bulky side
Lowest Price Found Here @ Amazon


Coway AP-1512HH Mighty Review

  • Price: mid priced under $250
  • CADR: smoke- 233 , dust- 246 , pollen-240 .
  • Room Size: small to medium space
  • Filters: Pre- carbon filter, True-HEPA, Vital Ionizer


It is a tough call to chose between the Coway AP-1512 HH Mighty Air Purifier and the Winix 5500-2. Both of these machines are very comparable when it comes to price and efficiency. Both have similiar mid range prices as well as good CADR ratings. The Winix comes in at a bit of lower price, however the Coway has slightly better user reviews.

One thing that makes Coway stand out is that is has a permanent fiberglass pre-filter, used to capture larger particle of dust and pollen. Many times air purifier manufacturers are opting to skip this step in air filtration in order to save money. There is also a carbon filter to absorb odors. However it has been noted through several reviewers that this carbon filter is thin and not much use. One drawback to this air purifier is that it fails to effectively reduce odors. The HEPA filter should have a lifespan of about 1 year, while the carbon filter should be replaced every months or so.

The Coway also has an ionizer to further freshen the air. Many people do not like the use of ionizer on air purifiers, as all ionizer create some level of ozone. There have been very little complaints of ozone levels from reviewers of this machine, and the ozone output seems to be very low. It has been certified to meet all standards of ozone production. However, if it is bothersome the ionizer can always be switched off.

Overall the machine has as sleek and stylish design. It has been well built and designed. The machine runs quiet on lower speeds, but can run a little noisy on higher speeds. This is the price that has to be paid for having the higher CADR rating. The higher ratings will always run a bit noisy side.


  • Medium  spaces
  • Great for removal of allergen particles
  • Auto mode/sensors
  • Washable pre-filter
  • 3 speeds
  • Energy Star rated
  • Runs quiet
  • Four stage filtration
  • Poor customer service
  • Runs loudly on high settings
  • Poor odor removal
Lowest Price Found Here @ Amazon



Honeywell 50250 Review

  • Price: around $150
  • CADR: 250
  • Room Size:  Medium
  • Filters: Carbon, HEPA

The Honeywell 50250 is an overall good quality air purifier for the cost. Generally it can be found in the price range between $150-$250. Amazon is currently offering it under $150. With its high CADR this is a great deal for an air purifier that can deliver fresh clean quickly.

It can cover up to 390 sq. ft of space, so it is a good option for either a small up to a medium space. One of the important features of this machine is that is been made lightweight at only 20 pounds. It has a carry handle and with its lightweight is has been made  portable enough to be move around easily. Another  feature of this machine is that it has a 360 degree airflow to freshen air in all directions.

The Carbon pre-filter has been designed to capture larger allergy producing particles, as well as reducing odors. The pureHEPA filter is designed to catch all airborne polutant up to 99.97%. The filter has a long lifespan and wont need to be replace for a few years. Because filters can sometimes be difficult to find in certain air purifier models as time goes on, it seems reasonable to go ahead and order a replacement filter at the time of the initial purchase. It is recommended that the pre-filter be replaced every three months.

This unit also has a filter life indicator light, and has there different speeds. On the lower speeds the machine is able to run quietly with just a background hum to it. The higher speeds are loud, as with other units that boast of high CADR. Th higher speeds just gush the air quicker, and thus make the louder noises. Most reviewers don’t mind the noise level on this air purifier.


  • Medium  spaces
  • Good value
  • Long-life HEPA filter
  • Well-constructed
  • Easy to Use


  • Not good for heavy odors or smoke
  • Loud on high speed
  • 2 filter system
  • Large and bulky
Lowest Price Found Here @ Amazon

Winix WAC9500 Ultimate Pet True HEPA Air Cleaner with PlasmaWave Technology Review – Best Air Purifier for Pet Owners


  • Price: can be found from $230- $330
  • CADR:  Pollen: 194,  Dust: 182, Tobacco Smoke: 183
  • Room Size: Small to Medium 
  • Filters: Carbon,TrueHEPA, PlasmaWave technology.

At a reasonable price, and good efficiency the Winix WAC9500 Ultimate Pet True Hepa Air Cleaner is a good value for most people looking for a way to reduce allergens in their home. It is an overall good air cleaner that covers a small to medium size room and does a good job at reducing the allergen particles from the air. It will work in a space up to 283 sq. ft.

This air purifier has a carbon prefilter to reduce odors, a TrueHepa filter to remove up to 99.97% of all airborne particles, and uses PlasmaWave technology to further freshen the air. According to Winix, Plasma Wave Technology utilizes both positively and negatively charged ions to neutralize viruses and and bacteria that are in the air. The ions combine with water vapor to create a substance known as Hydroxyls.  Winix claims that their  patented method will reduce harmful germs, viruses and bacteria without creating any harmful ozone.

The HEPA filter will only need to be replaced on a yearly basis. The filter is easy to replace, and the machine is overall easy to use.

The machine is able to run quietly on most speeds, but as with  many other machines the higher speeds run noisy. If being used in a bedroom at night, it is advisable to run the unit on a lower setting to control the noise level.


  • Small  spaces
  • Four speeds
  • No ozone created
  • Economical long lasting HEPA filter
  • Energy Star rated
  • Runs quiet on low settings
  • Not good for heavy odors or smoke
  • Not good for large spaces
  • Runs loud
  • unattractive
Lowest Price Found Here @ Amazon

HEPA Air Purifier Buyers Guide

What Is CADR?

CADR, or the the Clean Air Delivery Rate, is simply put, the volume of clean air that an air purifier can put out. It is expressed in cubic feet per minute. An example of this is that if a machine has given a CADR rating of 200 for dust, it should be able to reduce the amount of dust to the room the same as adding 200 cubic feet of clean air per minute would.

This number is an attempt to give an objective number to all machines so buyers can easily compare their air cleaning ability.  It is just one useful tool that buyers can use to compare machines. Usually, CADR will give three separate numbers for Tobacco Smoke, Pollen and Dust.

Comparing CADR ratings can be most useful when comparing two similar priced units or two similar manufacturers.

CADR numbers are tested by AHAM, the Association of Home Appliance Manufacturers. This group has been testing air purifiers since the 1980s. CADR numbers are only given out o portable air purifiers and not tested on whole home units.

The ratings for CADR are as follows:

  • Tobacco Smoke: 10-450
  • Pollen: 25-450
  • Dust: 10-400

A rating above 400 is considered excellent and a rating below 100 is considered very poor.

CADR does have some limitations that should be kept in mind.

  1. Not all companies choose to participate in AHAM’s CADR testing. Some high quality and very effective brands do not have ratings. Companies do have to pay a fee to participate in the testing.
  2. The machines are tested for a short amount of time (20 minutes)  on their highest setting. CADR does not indicate how effective the air purifier will perform over time. It also does not show the effectiveness of a machine that is running on a lower setting.
  3. The size of particles being removed is not being measured by CADR. Some machines maybe able to remove large airborne particles very well, but leave behind many of the smaller and possibly harmful particles.
  4. CADR does not test for the effectiveness of gas or odor filtration.

So as you can see, CADR can be a helpful guide when purchasing a new air purifier, but it does not give the complete picture.

 How does an air purifier work?

There a lot of different technologies that have been developed in order to best clean the air in your house. The are five main air cleaning techniques that are largely used by most air purifier manufacturers: HEPA filter, Activated-carbon , Ozone generators, Ionizer purifiers and finally UV light sterilizers.

For machines that use a filter to clean the air a motor or fan is simply used to suck air through the filter in order for it to collect particles from the air. HEPA filters (High Efficiency Particulate Air) has met the standards put forth by the U.S. Dept. of Energy for removing air particles. The material it is made of does not matter, as long as the filter can remove 99.97% of particles down to .3 micrometers in size.

Ionizers have created a method of using charged ions to clean the air. While most atoms in the air are neutrally charged, meaning they have an equal number of positive and negative electrons. The ionizer will discharge a small and intense electrical field and any molecules that pass through this field will be given an extra electron or they will lose an electron. This will give the molecule either a positive or a negative charge. Inside the ionizer, there are usually two metal plates, one with a negative and one with a positive charge. These plates will then attract the molecules that have been given a new charge. Furthermore the charged molecules will clump together, becoming larger and more easily picked up by a filter, or drop out of the air. Ionizers usually create low levels of ozone, and ozone could be potentially be toxic. While there are standards put out for  ozone output, it is important to look at and research each machine’s ozone output if this is a concern for you.

Activated-Carbon is usually added to a filter in order to reduce unpleasant odors or fumes in the air. Charcoal is very porous and the molecules will get stuck into it as they pass through. Some substances will even bond with the charcoal.

Ozone generators work by altering oxygen molecules into ozone. The makers of these types of air purifiers claim that their machines are able to disinfect the air. However, it is more controversial method of air purification. Others have claimed that ozone is not an effective air cleaner and that is can be a toxic gas.  Ozone generators have also not been approved by the EPA as a proven method of air purification.

UV light (Ultra-violet radiation) works by having micro-organisms that are present in the air pass under the UV light, which will sterilize them and make them harmless. Air purifiers that use this feature, have used it in order to clean the air from viruses, germs or bacteria.


Take a look at our Top 10 Air Purifiers reviews for 2017, before you buy.
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