It may come as no surprise to see that air purifiers come in all sorts of shapes, sizes and colors. What’s more important to notice, though, is not all air purifiers work the same. In fact, different types of air purifiers employ different technologies when cleansing the air you breathe.
It is vital to know and understand how each of these technologies work, so you can be sure to choose the right air purifier for your specific needs. Let’s take a look at the most five common types of air purifiers.
1. HEPA Technology
HEPA is an acronym for High Efficiency Particulate Air and is a technology that has been used for many years to filter particles. HEPA filters must meet a standard of trapping at least 99.97% of all particles larger than 0.3 microns. The human eye can only see particles larger than 10 microns; so particles caught in a HEPA filter such as chemicals, bacteria and viruses cannot be seen. Because HEPA filters are able to trap mold and bacteria, they create a more sanitary environment. Additionally, this type of air purifier does not generate ozone or any other harmful byproducts.
The HEPA filter is a very fine fiber-like material that has been folded back and forth to create the shape of an accordion. This accordion shape creates a maze of randomly arranged fibers and presents a very large surface for air to be pushed through by the air purifier fan. Airflow must have an opportunity to pass through the filter in order for it to be cleaned.
The more times airflow passes through the filter in an hour, the cleaner the air will become. As the HEPA filter becomes full, air will no longer be able to pass through and a new filter will be needed; however a HEPA filter will typically last 2 to 4 years.
Large particles will not be able to pass through the openings of the fibers and will immediately get caught. The smaller particles will get caught by one of three mechanisms. The first is when particles come within one radius of a fiber and stick to it. This mechanism is called interception. The second mechanism, called impaction, is when larger particles collide with fibers and embed into them. Finally, they get caught by a mechanism called diffusion. Diffusion is when the smallest particles collide with gas molecules. This, however, slows down their velocity and makes the first two mechanisms more likely.
HEPA air purifiers are the most effective at trapping airborne particles; however they do not remove odors, chemicals or gases. Therefore, most HEPA air purifiers have some level of activated carbon based material to absorb odors and chemicals not caught by the HEPA filter.
2. Activated Carbon Technology
Activated carbon is a form of carbon that has been processed to make it extremely porous and to give it a very large surface area for absorption.
The use of activated carbon dates back to the early 1900’s when it was sold commercially to purify water and to take the color out of sugar. During WWI, it was discovered that it could be used in gas masks to protect soldiers, as well as for war time water and air purifiers.
Activated carbon filters are comprised of many molecular sized pores that have high absorbent ability and chemical bonding. These properties make them a very effective tool for capturing pollutants such as chemical emissions, gases, tobacco smoke and odors. Once these pollutants are captured, they are not released back into the air, eliminating recontamination.
Air purifiers with activated carbon filters are particularly helpful to people with Multiple Chemical Sensitivity (MCS) because they absorb formaldehyde, which is found in carpet, wood paneling, and furniture upholstery. Perfumes, as well as chemicals in household cleaning items are also removed, making the environment much more breathable, especially for asthma sufferers, babies, children, and the elderly.
For many people, particulates such as dust, pollen or pet dander are the main irritants, with odor and chemical absorption being less important. For those who need a high degree of both, it is best to look at the high caliber room air purifiers which offer outstanding particulate, odor and chemical removal. Volatile Organic Compounds (VOCs) smog, ozone, fumes from cooking, pets or tobacco smoke can be unhealthy or irritating for anyone, not just those who suffer from allergies and asthma.
Carbon air filters help a great deal in reducing the contamination of the air in our rooms; however they do have a lower efficiency level in removing allergens and airborne particles. they also have limitations in eliminating contaminants that are far away and not forced through the filter.
3. UV Technology
UV technology is most often used in conjunction with particulate filter systems since it doesn’t really get rid of airborne particles. It is however, an excellent method to kill germs such as bacteria and viruses. Air purifiers using this technology have a UV lamp installed and as microorganisms pass by the UV rays radiated from the lamp, cellular or genetic damage occurs, destroying the microorganism.
A UV air purifier can convert molecules of oxygen and water found in your air into ozone and hydroxyl. The active molecules react with the air pollutants and destroy them into harmless components like water and carbon dioxide. Ozone is not needed for cleaning and since it can be a harmful pollutant, a good UV air purifier should minimize or eliminate ozone. The effectiveness of this type of air purifier is dependent upon the wattage of the light and the time of exposure to the light. The UV lamp should be monitored and replaced according to the manufacturer’s recommendations.
Although UV technology is effective at killing viruses and bacteria, it is best used with a filter system ahead of the lamps. Without a filter system, too many microorganisms get shaded from the light by particulates. Therefore, most air purifiers that employ UV start by filtering the air with HEPA and activated carbon and use the UV as a final stage of filtration.
4. Negative Ion
Negative ion air purifiers use chemical injections to clean the air. An ion is a natural particle with either a positive or negative charge. they get this charge be either gaining or losing an electron. Negative ions are simply oxygen atoms that have gained an electron. They magnetically attract airborne particles such as pollen and dust, until the newly-formed particle is too heavy to remain in air. This causes the particle to drop and attach itself to another solid item in the room, such as a window or a wall.
Although this technology may seem advanced, it has proven to be less effective than other air purifier technologies. Negative ion air purifiers merely mask the polluted air as opposed to actually cleaning it. Unfortunately, this type of air purifier does not have the ability to absorb or dispose of the harmful contaminants in the air.
The negative ion simply takes the airborne particles out of the air and transfers them to walls and surrounding solid items in the room instead of completely eliminating them. When they are stuck to walls and other surfaces, they have the ability to become loose and re-circulate themselves back into the air. Therefore, the negative ion air purifier has not cleaned and eliminated these particles and there is still a good chance they will contaminate the air again.
5. Ozone
Ozone air purifiers intentionally produce the gas ozone (O₃). Although many statements are made to make the public believe that these devices are safe and effective in controlling indoor air pollution, health professionals have refuted these claims and no agency of the federal government have approved of these devices. Exposure to ozone may ignite asthma symptoms and a high enough level can even scar the lungs.
There are many brands of ozone air purifiers on the market and they all vary in the amount of ozone they can produce. Many of the chemicals found in indoor environments take months or years for ozone to react, making them virtually ineffective. Also, ozone does not remove particles such as dust and pollen so most ozone air purifiers also include negative ion technology, which as discussed above, only masks the air as opposed to actually cleaning it. Studies have shown that ozone air purifiers may inhibit the growth of some biological agents, but it is unlikely to fully clean the air unless the concentrations were significantly higher than the public health standards.
HEPA
By far the most common type of filter in air purifiers, HEPA stands for High Efficiency Particulate Arrestance. These filters are ideal for particulate matter, such as pollen, mold or dust. As such, they are the general favorite of those who suffer from allergies or asthma. These filters are made from multiple layers of filter material, and are required by law to filter at least 99.97% of particles greater than 3 microns in diameter.
Carbon
Carbon, besides being quite lovely when compressed into diamond or useful in pencils, is an excellent filtration material. This is because of the porous nature of granular carbon. Having a large surface area with many pores, a grain or carbon can absorb contaminants directly from the air during the filtration process, making it ideal for smoke and gases that HEPA filters cannot catch, being sized at the molecular level. Carbon can also be treated with various reactive chemicals that will make this type of filtration even more effective.
TiO2 Filtration
Those familiar with either chemistry or painting may notice that the chemical formula TiO2 (titanium dioxide) is the same chemical compound used as a pigment in most white paints. However, it has an entirely different usage when it comes to air purification. TiO2 filters are used in many hospital grade filtration systems, such as the one in the Field Controls TRIO unit, as one of many filters. This filter technology is excellent for germs, smoke and unpleasant odors.
Ionizers
Usually used in conjunction with one or more other types of filtration, ionizers are devices that electrically charge molecules in the air to form ions. This causes particles in the air to attach to a grounded electrode, and also kills bacteria and viruses. Some people think that ionizers inherently produce large amounts of ozone. However, this is not true. Some, such as those used in various Bliueair models, cause no net increase in ozone in the air that is filtered.
Conclusion
Air purification isn’t always quite as simple as it seems. There are many different types of air purifiers that operate in many different ways. However, by understanding the uses of the various types of filtration systems, you can start to decide what will match your needs.
If you need more help picking out the right air purifier, you can email us at: contactus@usairpurifiers.com
The 7 Types of Air Purifiers and When to Get One
1. Ultraviolet Air Purifiers
Ultraviolet (UV) air purifiers use ultraviolet light to remove potentially harmful viruses, bacteria, and pathogens from your home. The inspiration for UV air purifiers came from hospitals that use special ultraviolet light bulbs to disinfect patient rooms and laboratories. Residential UV air purifiers are small, compact machines that filter the air in your home through a chamber filled with UV light. The UV light destroys pathogens by breaking molecular bonds in their DNA. Ultraviolet air purifiers can cost as little as $50 or as much as $800 depending on the model you purchase.
When to Get a UV Air Purifier
If you want to kill mold, germs, and other bacteria to prevent illness, UV air purifiers kill 99.9% of mold spores that pass through your furnace or air conditioner. Just keep in mind that because UV air purifiers use special light bulbs to reduce harmful particles from the air, the bulbs will need to be replaced every year or so, depending on the model and how often you run the purifier.
2. HEPA Air Purifiers
HEPA air purifiers use an advanced air filter to remove 99.7% of all particles larger than 0.2 microns from the air in your home. That means that HEPA air purifiers are highly effective at removing particles like pollen, dander, mold, and dust from the air. HEPA air purifiers cost between $30 and $300 depending on the model that you buy.
When to Get a HEPA Air Purifier
HEPA air filters are a consumer favorite because they’re effective at removing the vast majority of irritating particles and pollutants from the air. However, HEPA air filters must be replaced after every month of use. In addition, HEPA air filters cannot trap microorganisms smaller than 0.2 microns like germs, viruses, and bacteria.
3. Activated Carbon Air Purifiers
Activated carbon air purifiers are effective at removing smoke, odors, fumes, and gasses from the air inside your home. People who are sensitive to odors like smoke or natural gas should consider an activated carbon air purifier. Most activated carbon air purifiers include HEPA filters that remove particles from the air as well. Activated carbon air purifiers are priced at $100 and higher.
When to Get an Activated Carbon Air Purifier
If you want to remove odors and smells from your home, an activated carbon air purifier is the only type of air purifier that is designed to eliminate odors, chemicals, fumes, smokes, and gasses from the air. However, this means they are less effective at removing pollen, dander, dust, or mold from the air unless the model includes a HEPA air filter.
4. Ionic Air Purifiers
Ionic air purifiers are extremely quiet and operate without a motor. They emit negative ions into the air, which bond with positively charged, airborne particles like dust, making these particles so heavy that they eventually fall out of the air. Some ionic air purifiers have electrostatic precipitators that trap positively charged particles to a metal plate inside the air purifier. The price of ionic air purifiers range from $30 to $300 depending on the model and size of the air purifier.
While most ionic air purifiers are large, separate devices that need to be placed throughout your home, there is one type of ionic air purifier that is making waves in the world of air treatment. The new iWave-R from Nu-Calgon is one of the best air purifiers you can buy as it is the world’s first self-cleaning air purifier using ionic technology. Plus, the iWave-R air purifier attaches directly onto your HVAC system to ensure that your whole air supply stays clean, not just the room that you place it in. With the iWave-R in your home, you can enjoy all of the benefits of ionic purification without the drawbacks.
When to Get an Ionic Air Purifier
Ionic air purifiers can remove just about anything other than odors from the air. That includes dust, dander, allergens, smoke, viruses, bacteria, and fumes. Some models do need to be cleaned regularly in order to maintain functionality and fully remove air pollutants, but the new iWave-R is able to clean itself.
5. Electronic Air Cleaners
An electronic air cleaner is a whole-home solution that works with your furnace or air conditioner to charge and trap airborne particles using static electricity.
Electronic air cleaners can remove up to 99.98% of allergens from the air in your home using HEPA filters and positively charged ions. They purify the air in your entire home by using a HEPA filter in conjunction with your heating at cooling systems. In essence, an electronic air cleaner ensures that the air that passes through your HVAC systems also pass through a HEPA filter that can trap particles as small as .3 microns. Any remaining impurities are then zapped by positively charged ions generated by the electronic air cleaner.
When to Get an Electronic Air Cleaner
If you want to remove dust, dander, allergens, smoke, viruses, bacteria, or fumes from your home, an electronic air cleaners does a great job. They do need to be professionally installed, but with the ability to remove 99.98% of allergens from the air, they’re one of the most effective air purifiers you can buy.
In addition to a professional installation, it’s also worth mentioning that the cleaner’s filters must be replaced and the ionizing wires or collector cells must be cleaned after every month of use. Cleaning can be a simple event, however, as the cells can be washed in the dishwasher, in a tub, or with a garden hose.
6. Central Air Cleaners
Central air cleaners purify the air in your entire home by connecting to your central heating and cooling systems. Central air cleaners work silently in the ductwork of your home to remove up to 99% of the most and pollen in your home, 98% of the dust in your home and 94% of the viruses in your home. Central air cleaners can greatly reduce the impact of allergies, asthma and viruses on your health. They also help extend the life of your heater and A/C by filtering out particles that might otherwise interfere with the equipment.
When to Get a Central Air Cleaner
Wile central air cleaners need to be professionally installed, this type of air cleaner is very efficient, with upper-tier models having a 98% efficiency in removing particles that are less than one micron in size. From smoke to pet dander, a central air cleaner will take care of it all.
7. Air-To-Air Exchangers
Air-to-air exchangers actually ventilate your home by removing old, stale air and bringing in healthy, fresh air. Air-to-air exchangers can also help you regulate the temperature and humidity of your home using “energy recovery ventilators.” For instance, in the winter an air-to air exchanger will trap the heat from the air before ventilating it out of your home. This heat will be used to warm and humidify clean air entering your home in order to maintain an even temperature. In the summer, and air to air exchanger cools and dehumidifies clean air from outside before channeling it into your home.
When to Get an Air-to-Air Exchanger
If your home suffers from stale air or poor circulation, an air-to-air exchangers will bring the fresh air in from the outdoors. This helps regulate your home’s climate and reduces the amount of mold in the air.
Pure and Simple
If you want to improve your homes air quality, air purifiers and air cleaners are the way to go. More sophisticated than simple air filters, these devices work hard to eliminate potential pollutants and irritants from your home’s atmosphere. As a result, you can expect your allergy and asthma symptoms to improve. You can also breathe a little easier knowing that harmful particles won’t be waiting for you at home.
Are you ready to invest in a cleaner and healthier home? Contact us for more information and advice about which type of air purifier is best for your home and HVAC system.
HEPA Purifiers
HEPA purification technology has been around for decades, with the initial idea born from gas masks used in WWII and further developed with the Manhattan Project. As a tried-and-true method for purifying indoor air, HEPA purifiers are a common household item worldwide.
HEPA, which stands for high-efficiency particulate air, is a standard of filtration designed to strain out microscopic particles. To satisfy HEPA requirements, a candidate filter must remove 99.97% of particles of diameter 0.3 μm, with even greater filtering efficiency for larger and smaller particles. So, how do these filters and purifiers work?
How do HEPA purifiers work?
Using a fan, HEPA purifiers begin by drawing polluted air into the device. From here, the air passes through a filter, usually made of fiberglass, where airborne particles become ensnared in a maze-like tangle of fibers. Some particles stick to the fibers (interception), some become embedded in the fibers (impaction), and some get bounced around by other airborne particles or even gas molecules (diffusion).
The last component, known as diffusion, is especially important for trapping particles smaller than 0.1 μm. Because these particles are quite small, they could just fly through the filter without sticking to any of the fibers. However, because their “flight path” is interrupted by other particles, their trajectory becomes zigzagged, increasing the likelihood that the particles will get trapped by the other two methods.
The zigzagging path of tiny particles is due to Brownian motion, the random motion of particles in a fluid (in this case, air).
After the air passes through the filter, it is pumped back out into the room, and the purifier draws in more polluted air to purify. Eventually, most of the air in the room will cycle through the purifier, decreasing particulate matter levels dramatically.
Pros
There are many reasons HEPA purifiers have remained a common household item for decades. HEPA purifiers are very effective against particle pollution without any harmful byproducts, and many filters become more effective as they trap more and more airborne particles.
Another benefit of HEPA purifiers is that the filtration technology can be combined with other forms of purification for added bonus. For example, some HEPA purifiers come equipped with a UV prefilter, which kills microbes that are removed by the HEPA filter.
Cons
While HEPA purifiers are the most effective purifiers for particulate matter, they also require a lot of upkeep. HEPA filters don’t last forever, and you will have to replace them regularly to keep your unit in good shape. If you live in a heavily polluted area you will need to replace your filter more often, which can create costs and inconveniences.
For stationary filters in central air conditioning or ventilation systems, HEPA filters can also create additional energy costs by restricting air flow through the unit. Additionally, HEPA purifiers can’t remove odors or microbes (not reliably, at least).
Adsorbent Purifiers
Let’s take a step back from particulate matter and look at adsorbent purifiers. Often made of activated charcoal, adsorbent purifiers trap chemicals and odors that may be floating around your home. You may see adsorbents widely used in other environmental cleanup efforts because of their ability to sponge up toxic substances.
Adsorbents are widely used to mitigate environmental contamination, such as oil spills.
How do adsorbent purifiers work?
Rather than relying on a mechanical process like HEPA purifiers, adsorbent purifiers use materials called adsorbents, which attract substances to their surface through physical or chemical processes.
Physical adsorption uses electrostatic forces (van der Waals) between molecules, where polar substances like water are attracted to polar adsorbents, and non-polar substances are attracted to non-polar adsorbents. With chemical adsorption (chemisorption) substances chemically bond with the adsorbent. While physical adsorption can be reversed, chemical adsorption is largely irreversible.
As air passes through the purifier, unwanted gases are adsorbed into the porous bed of adsorbent material, releasing clean air free of these gaseous pollutants.
Pros
Adsorbent purifiers have no harmful byproducts, so adsorbent purifiers are quite safe to use around your home. They also remove pesky odors and VOCs, which HEPA purifiers and ionic purifiers cannot tackle.
Adsorbent filters can also be added to other purifiers like ionic and HEPA purifiers, so you receive the dual benefits of particulate matter and odor removal.
Cons
Adsorbent purifiers are rarely a stand-alone item, as it can’t remove airborne particulates, which are harmful to your health. To keep your air healthy, you will also have to invest in another purifier. Luckily, adsorbent purifiers are often included as prefilters in HEPA purifiers, so they are fairly easy to come by. Speaking of prefilters…
UV Purifiers
You know how sunscreens always say “UVA and UVB protection”? Well, this is because ultraviolet light from the sun destroys the DNA and RNA within your skin cells, which increases your risk of developing skin cancer. UV purifiers work the same way, but with microbes.
The stratospheric ozone layer protects us from UV-C light, the most dangerous to human health.
How do UV purifiers work?
Like HEPA purifiers, UV purifiers begin by sucking air into the device. UV purifiers then expose the air to a UV lamp, which generally produces UV-C light. Through a process of ultraviolet germicidal irradiation (UVGI), the UV light breaks down the chemical bonds formed between DNA molecules, which renders viruses inactive and can kill bacteria and fungi.
Pros
UV purifiers are unique; they target airborne microorganisms instead of nonliving particulates. In this way, UV purifiers have a wide range of applications in medical settings, especially as an antibacterial and antiviral disinfectant method. UV purifiers are also available as an addition to HEPA purifiers, which can help neutralize any microbes picked up by the HEPA filter.
Cons
The effectiveness of UV purifiers has been debated over the years, and the application of ultraviolet germicidal irradiation in air purification has come under fire because of the byproduct created by the process: ozone.
When UV purifiers expose air to UV light, the same energy that breaks the bonds of DNA in microorganisms can also split oxygen (O₂), which can reform into ozone (O₃). While beneficial high in the atmosphere, ozone is a dangerous pollution in your home. Luckily, ozone is produced at specific wavelengths of UV light, and ozone production can be dramatically reduced when UV purifiers only use ”safe” wavelengths.
A Note About Ozone:OzoneRead more about this in our dedicated article. is a compound formed by three oxygen atoms, often created by chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOCs). At the ground level, ozone can trigger a variety of health problems, especially for the elderly, asthmatics, and children.
Ionic Purifiers
Speaking of ozone, let’s discuss ionic purifiers. Popular in the 1990s and early 2000s, ionic purifiers offer a filterless alternative to HEPA purifiers. Culminating in the swift rise and fall of The Sharper Image Sonic Breeze, HEPA purifiers have overtaken ionic purifiers in popularity, primarily due to concerns that ionic purifiers produce ozone.
How do ionic purifiers work?
Ionic purifiers actually come in two varieties: ionizers and electrostatic precipitators (ESPs).
Ionizers create ions, which are positively or negatively charged particles. Most ionizers produce negative ions through a process known as a corona discharge, and the ions then attach themselves to particles floating around the purifier. The ionized particles then settle on surfaces around your home where you can easily wipe them down.
Electrostatic precipitators use a similar idea, but instead of landing on outside surfaces, particles settle on positively charged plates within the purifier. ESPs are more popular than ionizer for this reason, as particles are easily taken care of by cleaning the plates instead of cleaning the whole room.
Pros
Because ionic purifiers are filterless, they don’t need filter replacements and have lower upkeep costs. Likewise, ionic purifiers are much quieter than HEPA purifiers.
Cons
On the application side, ionic purifiers are generally less effective than HEPA purifiers for removing particulate matter, and ionizers, in particular, may create a mess as particles settle on surfaces.
In a study done by the state of California, ionic purifiers were found to release large quantities of ozone as a byproduct of the corona discharge. While this study found that ionic purifiers still produced ozone within safe outdoor ozone limits, California has banned the sale of ionic purifiers. Ozone can create particulate matter and contribute to higher levels of formaldehyde, both of which are very dangerous.
California was one of the first U.S. states to begin regulating the air purifier market.
Because of the ozone produced by ionic purifiers, we do not recommend ionic purifiers for home use. To eliminate particulate matter, we recommend instead that you invest in a HEPA purifier.
Ozone Generators
Now we come to the last entry on this list: ozone generators. Naturally, the fact that there’s “ozone” in the title implies that we do not recommend ozone generators for indoor use, but we believe that it is important to cover the purposes and limitations of ozone generators because of potential false marketing and their industrial applications.
How do ozone generators work?
Ozone generators (also known as ozone air purifiers or ozone air cleaners) use either a corona discharge or UV light to break apart oxygen molecules into two oxygen atoms, where they recombine into a molecule of three oxygen atoms which we call ozone. Ozone is highly reactive, often changing the chemical composition of surrounding molecules by “donating” an oxygen atom.
Pros
In industrial, non-occupant settings, ozone generators can be used to disinfect the air and kill microbes. Note that it is more applicable for biological contaminants, not airborne inorganic particulates or chemicals; for ozone levels to be effective in eliminating biological contaminants, ozone would have to exceed 5 to 10 times the public health limit. Thus, a use case for ozone generators exists in spaces without occupants.
Cons
For our discussion of the disadvantages of ozone generators, we will focus on the home setting, where ozone generators have no place being. No federal agency in the US government has approved ozone generators for use in occupied spaces.
First, ozone generators create copious amounts of ozone, which is immediately harmful to your health. The claim that ozone is beneficial or a form of medical treatment is completely false and should be a red flag.
Second, most studies show that ozone takes months to react with chemicals in the air, often leaving byproducts that are just as bad or even worse than the original chemicals. Ozone also can’t reliably remove particles from the air, so you would need an additional ionic or HEPA purifier to tackle particulate matter. For more information about the limitations and dangers of ozone generators, we recommend checking out the EPA’s page “Ozone generators that are sold as air cleaners.”
Key takeaways:
- We recommend using HEPA purifiers over ionic purifiers to eliminate particulate matter.
- To remove odors and some VOCs, use an adsorbent purifier or prefilter.
- If you use a UV purifier, check to make sure it uses “safe” UV wavelengths.
- Ozone generators should never be used in an occupied space!