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Air Purifier Technologies
What are the different air purifier technologies, and what are the strengths and weaknesses of each? There are basically 8 air purification technologies. 1) HEPA technology. 2) UV and UVC technology. 3) Induct or HVAC technology. 4) Electrostatic technology. 5) Ozone technology. 6) Furnace filters. and 7) Photocatalytic Oxidation technology. Let's take a look at each of these technologies and consider their strengths and weaknesses.
HEPA: HEPA filters are one of the best technologies for removing dust from the air. The more HEPA media you have, the better. Large HEPA machines typically have 60-100 sq. ft of warm rolled true HEPA material and last around 5 years. Small "table top" HEPA filters only have a few feet of HEPA material and can only last a few months, that is why most reports conclude that table top HEPA machines are mostly ineffective. (And costly) We all know the cons, replacement filter costs and noisy operation. I'll add another. The inability to remove VOC's and chemicals and the potential for captured bacteria to multiply within the filter media over the 5 year life of the filter. HEPA machines with 15 or more pounds of carbon-zeolite or special carbon matt filters can however address VOC and chemical issues, but not as effectively as photocatalytic oxidation.
UV air purifiers: There are many different types of UV air purifiers on the market. Some use UV wavelengths which produce ozone as a by product, others utilize UVC lamps which do not produce ozone. Some send the "friendly" oxidizers hydroxyl radicals and superoxide ions into the air via photo-catalytic oxidation with a reaction to the catalyst titanium oxide, yet other rely on powered UVC lamps with high UVGI radiation to zap the passing microorganisms. Many table top machines boast of UV germicidal protection but they feature low powered (8-10 Watt) UV lamps that lack the "dwell time" needed to do much of anything unless they also use a catalyst to produce oxidizers. Let's now take a look at the different UV technologies and weigh their strengths and weaknesses.
Air Oasis air purifiers utilize a much touted photo-catalyst oxidation technology to send friendly oxidizers into the air to kill mold and bacteria. They also remove many VOC's, chemicals, smog, and get rid of odors. These units have a patented catalyst that features 4 nano metals in their photocatalytic oxidation process. They have a mold test kit so you can see before/after mold reduction levels. They don't have filters so they don't remove dust. Cost: $309 for their 3000 sq ft unit. (or 1000 sq ft of polluted air)
Biozone UV technology mostly uses ozone to clean the air. UVC induct units such as the Calutech Blue or Ionic Zone IZ-UV72 produce over 24,000 microwatt's of UVGI to kill 99% of airborne pathogens that pass by the 2 UVC lamps. These units have an optional catalyst that can be attached to the unit and will also send friendly ionizers into the air to seek and destroy air pollutants. There are a number of HEPA machines that boast photo-catalytic oxidation with the use of a UV lamp and titanium oxide catalyst. This is a new and worthwhile technology to have in a HEPA air cleaner, however, most of the machines which feature this technology are made out of plastic (outgases) and table top models which have a very limited cleaning area (around 100 sq ft)
Induct: There are three types of induct air purifiers; filter, electrostatic, and UV. The filter type has it’s own blower to move the air into your HVAC system. Most HVAC fans can barely muster enough strength to push air throughout your home as it is, let alone clogging up the intake with a thick filter. (For this reason, we don't recommend thick furnace filters, 1" of MERV 11 is plenty) They are effective dust collectors, better than stand along HEPA machines, and they make less noise as well even though they have 2000 CFM (average) fans vs. 400-500 CFM fans. When it comes to CFM and ACH, it’s all about size and power. Because most of the particles in the air are so small they stay suspended, running your HVAC fan 24 hours a day will create good air movement in your home and change the air in your home 1-2 times per hour.
Electrostatic: The problem with electrostatic washable filters is that they allow too much dust to pass by. (Only MERV 2-3) I see many air purifier vendors selling those low quality washable furnace filters and some even tout the MERV rating at 11 or 12 which is laughable. Those things are worthless folks, and the margin is huge for the sellers, they're mostly sold online because you won't buy a $80 filter if you read MERV 2 or 3 on the label. (Most don't mention a MERV rating on the label by the way, buyer beware). Induct electrostatic units on the other hand plug into a power outlet and feature their own blower and a washable electrostatic grid that usually needs to be cleaned yearly. These types of units also feature filters quite often and are the best dust removing HVAC systems sold. Those units cost around $2000 however. For that reason, we recommend using a disposable MERV 11 filter for dust collection. If you spray TiO2 Magic photo-catalyst oxidative liquid on you MERV 11 filter, you'll also remove odors and VOC's from the air. We can't justify the need to pay $2000 up front and hundreds a year in filters when a MERV 11 will filter will only cost you $24 a year and collect nearly as much dust.
Ion Generators and Ionizer: Negative ions are "air vitamins'. You can have dust free air but if it's void of negative ions or has a higher positive ion count, you'll probably feel sluggish and irritable. Many detractors of negative ion generators say that the negative charge just pushed particles against he walls and surfaces. They fail to tell you about the benefits of negative ions, and that's a shame. They also fail to tell you that the particles they force from the air are so small that if the air wasn't ionized, they would remain suspended in the air until your lungs or nostrils act like a HEPA machine and filter them from the air. Over 80% of airborne particles are smaller than .3 microns. Yes, negative ions do force particles from the air onto surfaces but better there than in your lungs.
Some ionizers produce positive ions, the Ionic Breeze for instance which uses corona discharge. (also produces a good amount of ozone). Most ionizers lack a fan and will not elevate negative ions levels more than 3-4 feet from the front of the unit.
Electrostatic Air Purifiers: The same principle as ionizers only these air purifier feature steel grids to collect dust. The Friedrich C-90A is an example of an electrostatic air purifier. This is an effective way to remove dust from the air. The knock on this technology is that it often produces snapping and popping sounds, the grills are hard and awkward to clean, and these units lacks the pounds of carbon needed to remove odors and VOC's from the air and some produce significant amounts of ozone. The filters in this machine require frequent changes and it uses more electricity than HEPA machines, so all in all, it cost more to operate than the Austin Air Allergy Machine that also has a special carbon filter that lasts 30 times longer than conventional carbon filters and was developed by the military to protect the troops from gas attacks. Now that's a "best buy" if you ask me!
Ozone Generators as Air Purifiers: If you smoke in your home and you have kids, you should be shot. (Just kidding :) What I really mean to say is that your killing your kids! You're about the only group that could benefit from an ozone generator. (If you really want one, call us, we'll tell you where to get one of those $700 models with 2 plates for $350) I'd rather the kid’s breath ozone than second hand smoke if the truth be known. Second hand cigarette smoke has over 200 known cancer causing substances and ozone can oxidize all of them. Other than that, ozone in the air is only good for smoke remediation contractors or odor abatement jobs. (in unoccupied rooms) Medical ozone is a whole other story. If you have cancer, AIDS, or any disease, pure ozone (O3) has been shown in many studies to be a cheap, highly effective treatment and cure, and therein lies the problem. (Cheap). The powers that be would rather sell you expensive drugs than administer a substance that's cheap and can't be patented. Medical ozone machines that utilize a pure oxygen feed can be had for under $1000 dollars and treat thousands of patients a year for next to nothing. Big business hates it, as you can imagine. How many politicians do you think have pharmaceutical stocks in their portfolio? Don't expect this travesty of justice to be corrected any time soon. There are a some brave U.S. doctors practicing ozone therapy at the risk of being jailed or losing their license. Enough said.
Furnace Filters: Many people will run out and buy a table top HEPA machine and spend over $100 a year on replacement filters then skimp and buy a $3 furnace filter for their home. If they only knew that the HVAC system is more powerful than several HEPA machines combined, let a lone a small table top HEPA machine that can only clean the air in a small bedroom. The formula for figuring out air changes per hour (ACH) is: ACH = (CFM X 60 minutes)/(room volume in cubic feet) Most HVAC systems that can treat 2000 sq. ft homes use 2000 CFM fans and change the air in the home 2-3 times per hour. That's a lot of wasted filtering potential if you don't use MERV 11 filters! If you coat your MERV 11 filters with TiO2 PCO Solution photocatalyst spray, your MERV 11 filter will also become a VOC and odor removing filter. Running your HVAC system 24 hours a day will only cost you about $5 a month in electricity. It can also turn your HVAC system into the best air purifier you could possible have in your home.
Photocatalytic Oxidation: UV air purifiers that feature a Titanium Oxide catalyst and other nano metals produce the friendly oxidizers hydroxyl radicals and superoxide ions to clean the air via a process known as photo-catalytic oxidation. One university studies tout this process as the best air cleaning technology for it's ability to remove VOC's from the air. The same group claims carbon/ HEPA machines create other problems once they oxidize VOC's. (never read that before, just throwing it out there) These oxidizers are 1.5 times stronger than ozone yet they do not irritate the eyes and lungs like ozone which makes this technology the technology of the future. TiO2 solution can also be applied to fabrics and surfaces to make them self-cleaning, odor, and microorganism resistant. I predict that photo-catalytic oxidation will one day become the air purifier standard as more and more people come to realize that it's mostly the VOC's, gases, mold, and bacteria in the air that make them sick and leads to "sick home syndrome".
So which air purification technology is the best? Well that would all depend on your budget and also your main objective. We do know that everyone can and does benefit from the use of MERV 11 filters ($6) sprayed with Nano TiO2 PCO liquid ($25) and a UVC induct system. ($219). Most everyone can benefit from the use of Air Oasis units as well. If you need extra dust removal capabilities, my choice for the best HEPA machine values in the world would be 1) The AustinAir Allergy Machine and 2) Airpura I-600 with the optional carbon cloth filter. (This is the machine I use in my main living area, enough said) Both will remove dust and VOC's from large areas. (up to 1000 sq ft with 4 ACH). If you're on a budget, MERV 11 filters, TiO2 PCO liquid, and a few IZ-270 electrostatic air purifiers ($29) will produce the biggest bang for the buck. Also, if you're a pet owner and want to remove pet odors, the Austin Air Pet Machine is worth checking out.
They say that an ounce of prevention is worth a pound of cure so don't forget to keep VOC producing solvents from your home, choose non petroleum based carpets and furniture, for god's sake don't smoke in your home or use chemical air fresheners, and let in some fresh air every now and then, it won't kill ya, unless you live in Los Angeles I guess. All kidding aside, while the air outside might be filled with car exhaust and smog, the air inside your home is 2-3 times worse. So invest in some wise air purification technologies and you can rest assured that your health and the health of your family will benefit immensely.
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