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Air Cleaning Technologies

Air Cleaners and Air Purifiers

Honeywell HEPA Air Cleaner

An Overview of Air Cleaning Technologies


Air cleaners and HEPA filters were originally developed during World War II to prevent discharge of radioactive particles from nuclear reactor facility exhausts. Air cleaner technology has since become a vital technology in industrial, medical, and military clean rooms and have grown in popularity for use in portable residential air cleaners. A true HEPA filter for an air cleaner is defined as having a minimum particle removal efficiency of 99.97% for all particles of 0.3 micron diameter. The HEPA rating of an air cleaner or HEPA filter is determined using a test with particles of 0.3 micron average diameter. To qualify as a "true" HEPA air filter or air cleaner, the air cleaner or air filter must allow no more than 3 particles out of 10,000 to penetrate the filtration media. Warning: Air filters using less efficient filtering materials are frequently being referred to as "HEPA-type" filters, though their actual efficiency may be 55% or less at 0.3 microns.

In case you're wondering how small a micron is, it is one-millionth of a meter and there are 25,400 microns in a single inch.

Air Cleaner Model

Max Room Size
(4-6 Air Changes/Hour)

Price Air Filter Technology
(Replacement Timeframe)
Austin Air Healthmate HM400 Air Cleaners 20' x 25' $538.99 Pre-Filter (5 Years)
HEPA Filter (5 Years)
VOC Filter w/ 15 lbs of Granular Carbon and Zeolite Mix (5 Years)
Austin Air Healthmate Junior Air Cleaners 10' x 12' $374.99 Pre-Filter (5 Years)
HEPA Air Filter (5 Years)
VOC Filter w/ 6.5 lbs of Granular Carbon and Zeolite Mix (5 Years)
Austin Air Healthmate Plus Air Cleaners 20' x 25' $648.99 Pre-Filter (5 Years)
HEPA Filter (5 Years)
VOC Filter w/ 15 lbs. Granular Carbon (Impregnated w/ Potassium Iodide) and Zeolite Mix (5 Years)
Austin Air Healthmate Plus Junior Air Cleaners 15' x 17' $418.99 Pre-Filter (5 Years)
HEPA Filter (5 Years)
VOC Filter w/ 6.5 lbs. Granular Carbon (Impregnated w/ Potassium Iodide) and Zeolite Mix (5 Years)
Austin Air Allergy Machine Air Cleaners 20' x 25' $574.99 Pre-Filter (5 Years)
HEGA Filter (5 Years)
High Efficiency Gas Absorption with Activated Military Carbon Cloth (5 Years)
Austin Air Allergy Machine Junior Air Cleaners 15' x 17' $394.99 Pre-Filter (5 Years)
HEGA Filter (5 Years)
High Efficiency Gas Absorption with Activated Military Carbon Cloth (5 Years)
Austin Air Pet Machine Air Cleaners 20' x 25' $594.99 Pre-Filter (5 Years)
HEGA Filter (5 Years)
15 lbs. of Specialty Carbon/Zeolite Blend (5 Years)
Austin Air The Bedroom Machine Air Cleaners 25' x 30 $764.99 Pre-Filter (5 Years)
HEGA Filter (5 Years)
15 lbs. of Proprietary Carbon Blend (5 Years)
Austin Air Baby's Breath Air Cleaners 15' x 17' $394.99 Pre-Filter (5 Years)
HEGA Filter (5 Years)
High Efficiency Gas Absorption with Activated Military Carbon Cloth (5 Years)
Blueair 203 HEPA Air Purifier 10' x 17.5' $329.00 Ionic Charge Chamber (N/A)
3-Stage HEPA Filter (6 Mo.)
Carbon Filter Upgrade Available
Blueair 403 HEPA Air Purifier 19' x 20' $549.00 Ionic Charge Chamber (N/A)
3-Stage HEPA Filter (6 Mo.)
SmokeStop Filter Upgrade Available
Blueair 503 HEPA Air Purifier 24' x 24' $659.00 Ionic Charge Chamber (N/A)
3-Stage HEPA Filter (6 Mo.)
SmokeStop Filter Upgrade Available
SurroundAir Vent System
Blueair 603 HEPA Air Purifier 23' x 28' $769.00 Ionic Charge Chamber (N/A)
3-Stage HEPA Filter (6 Mo.)
SmokeStop Filter Upgrade Available
SurroundAir Vent System
Blueair 450E Digital HEPA Air Purifier 14' x 26' $629.00 Ionic Charge Chamber (N/A)
3-Stage HEPA Filter (6 Mo.)
Optional SmokeStop Filter For Advanced Gas & Odor Filtration
Digital Control Features
Blueair 650E Digital HEPA Air Purifier 20' x 35' $849.00 Ionic Charge Chamber (N/A)
3-Stage HEPA Filter (6 Mo.)
Optional SmokeStop Filter For Advanced Gas & Odor Filtration
Digital Control Features
Blueair ECO10 HEPA Air Purifier 15' X 20' $699.00 Ionic Charge Chamber (N/A)
HEPA Particle Filter (Set of 3) (12 Mo.)
HEPASilent Technology
Energy Efficient
HEPA+ 2000 Air Cleaners 12' x 12' $399.99 $299.99 Washable Pre-Filter (3-6 months)
HEPA Filter (2-5 Years)
Inner Carbon Filter (6-12 Months)
Optional VOC Filter (12 Months)
HEPA+ 3000 Air Cleaners 20' x 20' $749.99 $399.99 Washable Pre-Filter (3-6 months)
HEPA Filter (2-5 Years)
Inner Carbon Filter (6-12 Months)
Optional VOC Filter (12 Months)
Honeywell Enviracaire 50150 Air Cleaners 15' x 15' $141.99 Activated Carbon Pre-Filter (3 months)
Lifetime HEPA Filter (Clean Every 6 mo.)
Honeywell Enviracaire 50250 Air Cleaners 17' x 23' $181.99 Activated Carbon Pre-Filter (3 months)
Lifetime HEPA Filter (Clean Every 6 mo.)
Honeywell Quietcare 17005 Air Cleaners 14' x 14' $151.99 Activated Carbon Pre-Filter (3 months)
Lifetime HEPA Filter (Clean Every 6 mo.)
Hunter QuietFlo 30090 Air Purifier 11' X 13' $99.99 Activated Carbon Pre-Filter (3 months)
HEPA Filter (1 Year)
IQAir HealthPro Compact 14' x 20' $799.00 PreMax Pre-Filter (6-18 months)
HyperHEPA Filter (2-4 Years)
IQAir HealthPro 14' x 22' $849.00 PreMax Pre-Filter (6-18 months)
HyperHEPA Filter (2-4 Years)
IQAir HealthPro Plus 14' x 20' $899.00 PreMax Pre-Filter (6-18 months)
HyperHEPA Filter (2-4 Years)
V5 VOC Filter (1-2 Years)
IQAir GC MultiGas 30' x 30' $1199.00 PreMax Pre-Filter (6-18 months)
Post-filter Sleeves (Up to 3 years)
Gas cartridges (6 to 24 months, depending on operating environment.)
Whirlpool Whispure AP250 Air Cleaners 16' x 20' $199.00 Activated Carbon Pre-Filter (3 months)
HEPA Filter (1+ Years)
Whirlpool Whispure AP450 Air Cleaners 20' x 25' $249.00 Activated Carbon Pre-Filter (3 months)
HEPA Filter (1+ Years)
Whirlpool Whispure AP510 Air Cleaners 22' x 23' $299.00 Activated Carbon Pre-Filter (3 months)
HEPA Filter (1+ Years)
Whirlpool Whispure APT40010R Tower HEPA Air Purifiers 12.5' x 16' $179.99 Activated Carbon Pre-Filter (3 months)
Two HEPA Filters (1+ Years)
Vapor-Eze Clean Air 5000 HEPA Air Cleaner 12' X 15' - Cars, RV's, Boats, Motel Rooms, Offices $61.99 Activated Carbon Pre-Filter (4 months)
HEPA Filter (4 months)


Negative ion generators, as opposed to HEPA air cleaners, force high-voltage electricity to one or more needlepoints. Electricity is simply electrons in motion. Since electrons repel one another, when they reach the needlepoint, they jump off and attach themselves to the molecules in the air, forming negative ions. At that point the allergens and other particles are attracted to grounded surfaces where they can get rid of that extra electron, causing them to settle on walls, floors, furniture and even on your bed. It's important to remember that a simple negative ion generator doesn't capture or collect the allergens in the air like air cleaners do, it simply causes them to precipitate out of the air.

Traditional furnace air filters do very little to remove allergens and other dangerous particles from the air. Standard furnace air filters have an efficiency rating of only 2% for particles between 0.3 and 1 microns in diameter. Those are the most dangerous particles because they get the deepest into your lungs and cause the most damage. Furnace filters have to balance filtration with airflow through your ventilation system. If a HEPA air filter were installed in place of a traditional furnace filter, airflow in your ventilation system would grind to a halt and it could damage the system. There is just not enough power in your ventilation system to circulate the air in your house through a HEPA filter. The need to balance filtration with airflow is why traditional furnace filters are so inefficient, but there are much more efficient filters and external add-on filtration systems available that balance airflow with filtration and do a much better job of filtering out allergens and other small particles as your ventilation system runs.

Electrostatic filters are based on the fact that most allergens and other particles in the air have a positive charge. While the filtration media is not much finer than a top-of-the-line traditional furnace filter, they are built with filtering materials that have a permanent negative charge. In addition to their ordinary filtering ability, electrostatic filters attract positively-charged allergens and other small particles to the negatively-charged filter much like a magnet. Electrostatic filters come as permanent washable filters and as quarterly disposable filters. It's important to clean permanent electrostatic filters monthly and replace disposable filters quarterly in order to maintain their effectiveness against small particles. Once the negatively-charged fibers get covered in dust, their ability to attract particles with an opposite charge is diminished, and more and more small particles like allergens can get through.

Furnace Filter Comparison *
Filter TypeNumber of Brands TestedPrice RangeEfficiency at Removing Particles Between 0.3 and 1 microns
Fiberglass 3 $.50 to $2 2%
Ordinary Pleated 7 $3 to $6 4 to 10%
Washable Electrostatic 5 $25 to $100 6%
Pleated, Disposable Electrostatic 6 $8 to $20 18 to 58%


* Diagram adapted from a paper presented by Kinzer, K.E. and Moreno, R.C., 1997, "Performance Comparison of Residential In-Duct Air Cleaning Devices" at the proceedings of The Tenth Annual AFS Technical Conference.

There are also a few solutions that filter air externally, before it even enters your ventilation system, but they require installation by a HVAC professional and can cost as much as several thousand dollars. Whole-House HEPA filtration systems are one example of external furnace filters. They use a very powerful fan to pull air out of the return duct and through the HEPA filter before feeding it back into furnace.

Another external furnace filtration technology is electrostatic precipitators. Electrostatic precipitators are used to clean the air coming out of factories, but the same technology has grown in popularity in home ventilation systems and some room air cleaners. They are ionizers designed to collect the allergens and other particles from the air once they have been charged. First, the air is passed through an ionizer where the particles gain a particular charge. Then that air is passed between plates with the opposite charge that attract the charged particles. Electrostatic precipitators have one major drawback though; they rapidly loose effectiveness as dust builds up on the plates. Studies have found that plates need to be cleaned as often as every week in order to maintain their effectiveness.

There are several other filtering technologies on the market: activated charcoal, zeolites, UV light and ozone. They are ineffective at filtering out small particles, but are often teamed with the filters we've discussed above within air cleaners to provide added protection against microorganisms, gases, and odors.

Activated carbon and zeolites are primarily used in HEPA air cleaners to filter odors, gases and other volatile organic compounds (commonly referred to as VOC's) out of the air. They are often teamed with other air filters in air cleaners to provide the added benefit of removing things like cigarette or pet odors, paint fumes and cleaning chemicals out of the air.

UV lights are commonly used in the air purification systems at hospitals and other medical facilities because of their ability to kill bacteria, viruses, mold and other microbes. When the microorganisms in the air are exposed to it, the UV light penetrates the organisms' membranes and alter their DNA. The altered DNA causes the microorganisms to no longer be able to reproduce and once bacteria and viruses lose the ability to reproduce they are no longer harmful.

Warning: Ozone generators don't filter anything out of the air, and have been widely debunked as a residential air cleaning technology. For more information about the ineffectiveness and the dangerous health consequences of ozone generators the EPA has put together an excellent publication, "Ozone Generators that are Sold as Air Cleaners: An Assessment of Effectiveness and Health Consequences". Both negative ion generators and electrostatic preciptators may produce some ozone as a by-product of their air cleaning. So when you're considering these units, it's important to make sure that they don't produce unsafe levels of ozone.

Where to Go From Here


During the course of our 15 years in the business, we've seen a lot of research and received feedback from thousands of customers on HEPA air cleaners and air ionizers. That had lead us to believe that for most people the best strategy for cleaning the air in your home often involves a combination of technologies at two different levels - the whole house air cleaner and individual room air cleaners.

For the whole house, it's important to use a high quality furnace filter to prevent allergens and other particles from being scattered throughout your home as your heating and/or cooling system circulates air. If you don't have central air, then it is just as important to replace the filters in your window A/C units regularly.

The next step is to target the individual rooms where you and your family spend a lot of time. Bedrooms are the first area that come to mind, since most people spend more time in their bedroom sleeping than in any other room. For cleaning the air in individual rooms, National Allergy recommends HEPA air cleaners for most people, because they are the most effective filters at trapping particles and getting them safely out of your environment. But in order to clean the air, it is absolutely essential that the HEPA air cleaner be suited for the size of the room you wish to clean. To clean the air throughout a room, it must be able to circulate all the air in the room through the air cleaner at least 6 times an hour. All air cleaners in the National Allergy catalog and website list the maximum effective room size, but we've also put all that information together on a single chart, National Allergy's Air Cleaners at a Glance, to make it easy for you to find the right air cleaner for your room.

Our Austin Air Cleaners are a perfect example of the same sort of complementary technologies combined to clean the air in individual rooms. With over 15 pounds of activated carbon and zeolites and a HEPA filter, Austin Air Cleaners do an unparalleled job of providing refreshing air cleaned of particles, chemicals and odors in rooms up to 20 x 25'. To top it off, the filters only need to be replaced every 5 years under normal circumstances and all Austin Air Cleaners come with free ground shipping for your entire order!

And finally, remember that if you are dust mite allergic, placing an air cleaner in your bedroom will bring you only minimal relief unless you encase your bedding as well. Sleeping with your face so close to bedding filled with the allergen is something that no air cleaner can overcome.


This information is for educational purposes only. Always consult with your doctor first about your specific condition, treatment options and other health concerns you may have.

If you have additional questions about the content on this webpage, email us at info@nationalallergy.com or call one of our phone experts at 1-800-522-1448.

 

 

Article Quick Read
  • To qualify as a ""true"" HEPA air filter, air cleaners must allow no more than 3 particles out of 10,000 to pass through the filter.
  • A negative ion generator doesn't capture or collect the allergens in the air like air cleaners do.
  • Standard furnace air filters have an efficiency rating of only 2% for particles between 0.3 and 1 microns in diameter.
  • Electrostatic filters attract allergens and other small particles to the negatively-charged filter much like a magnet.
  • Ozone generators do not filter anything out of the air.
  • HEPA air cleaners are the most effective filters at trapping particles and getting them safely out of your environment.