Is a filterless air purifier equal to the hype? Is a filterless air purifier right for you? Would you like to know more about the limitations of filterless purifiers before you make your final decision?
I understand that you sincerely want to make a good decision when it comes to your family’s health. Shouldn’t you have as complete an understanding of the facts as possible? The marketing behind filterless air cleaners can be very compelling. However, like all marketing, it can be very biased, presenting only the most favorable information for their products. Often, real and imagined “deficiencies” of competitors are exaggerated well beyond what is reasonable. This is certainly the case when it comes to “no filter” air purifiers. In one advertisement after another you find air cleaners based on varied technologies proclaiming “no filter replacement”.
Oh, how difficult it must be changing filters, since the filter free purifiers insist on how you need no tools.
Oh, how messy filters must be to replace, they imply as they show some poor woman gagging on dust.
Oh, how expensive filter replacement must be, with some vendors quoting costs in the thousands. But is a filterless air purifier really the ideal solution to your air quality problems?
What are your filterless air purifier choices and how do they work?
Allow me to introduce you to the primary technologies found in filterless air cleaners:
- Electrostatic precipitators(often called ionics by vendors)
- Ion generators (the true ionic cleaner)
- Ozone generators
- Photocatalytics
- Plasmacluster ionics
The electrostatic precipitator
The electrostatic precipitator charges particles in the air and then uses a series of collector plates with an opposite charge to attract the particles to the plates. It is possible for particles as small as 0.1 micron to be collected this way.
The ion generator
True ionizers simply emit ions into the air. These attach to airborne particles and cause them to aggregate into clumps until they fall to the floor or stick to walls, draperies, or furniture. While these filterless air purifiers help clear the air the dirt is not removed permanently.
The ozone generator
Ozone generators purposefully have ozone emissions that push the limits of what is considered acceptable for human exposure. The claim is that ozone destroys particles and gases and odors and that it is healthful to breathe. The scientific consensus is that such claims are completely false. This is the position the US Environmental Protection Agency and Federal Trade Commission take. Until the law is strengthened, these devices will continue to be marketed as air cleaners and continue to do harm.
The photocatalytics
Plasmacluster Ions
A new technology developed by Sharp. These ions are drawn to airborne contaminants like bacteria and viruses by their electrical charge. The ions surround the contaminant and form hydroxyl radicals that ultimately destroy the contaminant. This technology has been proven effective against biological pollutants like mold, pollen, viruses and bacteria as well as chemical and particulate contaminants. But this technology is also generally combined with filtration.
What are the top ten drawbacks of filterless air purifiers?
- Low efficiency. Scientific evidence indicates that home ozone generators are all but zero percent capable of cleaning the air. The best models of electrostatic precipitators only achieve about 80% efficiency at particle removal. Ion generators have some effect but precise measurements are hard to come by, and besides, any particles they help settle out of the air are easily disturbed and reintroduced into the air. Photocatalytic and plasmacluster air cleaners work best on only the smallest of particles.
- Rapid loss of efficiency. Loading of electrostatic precipitator collector plates with captured particles rapidly degrades efficiency at collecting further particles. Efficiency can be reduced to below 20% in as few as three days. CADR (Clean Air Delivery Rate) labels on air cleaners indicate that the stated performance refers to the first 72 hours of use. This is because the voluntary testing is limited to 72 hours, primarily due to the fact that manufacturers know their products cannot sustain high efficiency. Ozone generators are worthless to begin with. Ion generators can suffer from corrosion and contamination of electrode pins and wires, reducing their ability to generate ions. Similar contamination buildup on the semiconductor plate of photocatalytics can reduce effectiveness.
- Constant maintenance. The rapid reduction in collection efficiency due to electrostatic precipitator plate loading requires regular maintenance cleaning. From twice a week to daily is recommended, depending on the environment. This sounds like a lot of work for the “benefit” of a “no maintenance”, “no filter replacement” filterless air purifier. Ion generators also need regular maintenance of their electrodes, cleaning them with an alcohol swab.
- Reduction in efficiency over life of unit. Even with regular maintenance cleaning, collection efficiency will degrade due to deposits that simply cannot be removed. This is an even greater problem when cleaning is not regular. This degrading over the life of the unit can effect all filterless air cleaner technologies.
- Short life. Corrosion of the ionizing wire or needlepoint ionizing pins, electrical failures of the high voltage systems, and other problems can lead to product failure. Hence, warranties of filter free air purifiers tend to be far shorter than the five to ten years available on better quality HEPA air purifiers.
- Ozone production. Electrostatic precipitators and ozone generators produce ozone, a hazardous gas that damages the tissues of the airways causing increased sensitization to allergens, difficulty breathing for asthmatics, and possible severe respiratory distress. Photocatalytic and plasmacluster air cleaners are ozone free.
- Limited area due to low airflow. The need for ionized particles to spend sufficient time in the air electrostatic precipitators to be charged and then deflected onto the collection plates means air speed must be low. This limits the amount of clean air that can be delivered by the units. Likewise other filterless air purifier systems also tend to demonstrate much lower clean air delivery than can be achieved by a good HEPA filter air purifier. Of course, clean air delivery for an ozone generator is essentially zero, especially since ozone is itself a pollutant.
- No effect on gaseous contaminants. Chemical toxins, mold mycotoxins, volatile organic compounds, formaldehyde, the hundreds of chemicals in cigarette smoke all pass through an electrostatic precipitators unaffected. Ion generators likewise have no effect on chemical pollutants. Ozone generators, while marketed as being able to destroy these contaminants have consistently failed to do so in scientific studies. What is more, breakdown products of ozone oxidized contaminants have been shown to be more toxic than the original pollutants and more numerous. Photocatalytic and plasmacluster air purifiers do show excellent promise in handling chemical contaminants.
- Black wall effect / Black lung. Ionized particles created with an ion generator will collect on walls, furniture, or any available surface. This includes the inside surface of your lungs. This effect has been given a name. It’s called the black wall effect. The EPA has noted the health hazard of negatively charged respirable particles adhering to your lung tissues. See: Possible effects of particle charging
- Arbitrary pricing serves as no guide. Testing often shows that high priced filterless air purifiers may perform no better or even worse than cheaper models. Consumer Reports has periodically tested a number of the market leaders in this category and given them poor ratings due to inadequate performance and ozone production. Quality of materials and construction, durability, and effectiveness do not seem to play a consistent role in pricing. Rather, it seems the basis for price is simply what the market will bear and what their advertising budget can convince people to pay for the promise of clean air.
Are there filterless air purifier alternatives?
It’s very understandable to want an air purifier that is effective, reasonable in cost, low maintenance, and has low long term cost of ownership. That’s why a filterless air purifier appeals to so many.
The idea of “filter free” seems to solve maintenance and long term cost issues. Unfortunately, this isn’t really the case, and effectiveness tends to also be sacrificed. Plus, the initial cost of these air cleaners can often equal that of a good HEPA air cleaner.
There are better alternatives to “no filter” air purifiers that really can be reasonable in total cost and easy to live with. Allerair air purifiers and Austin Air air purifiers are two that stand out.
These two manufacturers both offer a variety of models that are reasonable in initial cost, use filters that last up to five years and are economical and easy to replace with no tools.