For far too long the air purifier industry has sold products without fully disclosing those products' real capabilities. I'm sorry to say, there are many air cleaners that are not worth buying. This is due to failure in the single most important quality measurement, total air purifier efficiency.
Consider an illustration. A small town depends upon a levee to hold back a rain-swollen river. What if the levee is not tall enough? What if it does not extend far enough? What if it has a breach somewhere? In any of these cases the town is not protected and any confidence they have is misplaced.
Many have been led to put confidence in this or that air cleaner. Is that confidence well placed? Or are there inadequacies that the marketing didn't reveal?
Let's consider the air purifier efficiency of some of the most popular types of air cleaners.
Air Purifier Efficiency in Ionic Air Cleaners
Late night infomercials have made ionic air cleaners seemingly indispensable. How miraculously they clear the smoke from a sealed chamber! Everyone just has to have one. But what are you really getting?
Ionic air purifier efficiency is affected by several factors. The intensity of the electrostatic charge, the speed of the airflow passing by the collection plates, the degree of soiling already on the plates all play a role.
The fact is that even the best electrostatic precipitators under the best of circumstances are only about 80% efficient. On any given pass, only 80% of the particles in the air are removed. This can quickly degrade due to plate loading. Studies have shown that in as few as three days ionic air purifier efficiency can degrade to only 20%.
This means almost daily maintenance cleaning to ensure top performance. Given the inadequacy of even top performance, I would recommend that you simply install a high efficiency HVAC filter. A MERV 13 Filtrete filter can easily do as much air cleaning and allergen removal as many ionic air cleaners. Plus you get the added benefit of much less cost and only changing them once every three months.
Air Purifier Efficiency in Ozone Generators
This one is considered only because they are so prevalent not because they have any merit. Scientific evidence indicates that home ozone generators are all but zero percent capable of cleaning the air. Ozone does not attack and neutralize pollutants as claimed. As long ago as the 1930's studies showed that ozone didn't reduce particle concentrations in air or eliminate chemicals and odors.
The claim that highly reactive ozone reacts with pollutants can be said to be accurate. That it fully decomposes pollutants is a lie. The truth is these reactions more times than not result in additional pollutants as the partially decomposed byproducts remain in the air. Ozone also reacts with everything else in the room; construction materials, furnishings, textiles, etc. resulting in even more pollutants, not less.
Add to this the fact that ozone is itself a pollutant, aggravating respiratory problems and inflaming lung tissues, you could say that air purifier efficiency in ozone generators is less than zero.
Air Purifier Efficiency in HEPA Air Cleaners
The gold standard of air purification is HEPA filter efficiency. You will see HEPA air cleaners proudly marketed with that 99.97% efficient at 0.3 micron rating. This is at once true and misleading.
That efficiency rating is for the HEPA filter material itself, not the air purifier that uses it. In some HEPA based air cleaners as much as 40% to 50% of air entering the cleaner may actually bypass the filter. Reasons range from poor sealing of the filter in the housing, cracks in the filter media and even deliberate design to reduce backpressure on an inferior motor.
It is agreed that HEPA filter air cleaners do provide the best overall air purification. However, it is absolutely essential to understand that the term HEPA should not equate to immediate trust of the purifier using it. You must examine any air purifier you are considering with a more critical eye.
Certain air purifier manufacturers have built their reputation on supplying only the highest quality air purifiers. My personal favorites are IQAir, Allerair, BlueAir and Austin Air. Of all air purifier manufacturers, IQAir has especially set itself apart. IQAir will provide you with certification of their air purifier efficiency as a complete system. This means you can know exactly how clean the air is that exits the air purifier. I hope that one day consumer pressure or regulation results in all manufacturers doing the same. Only then can any of us be certain we are getting what we are paying for.