Choosing the Best Air Cleaner

From ionic air cleaners to hepa air cleaners and filters

by Mercia Tapping, President, AllergyBuyersClub.com

We received a question recently about how to choose the best air cleaner. This is a complex topic to which I will try and give you some simplified information and then make some brief comments about specific air cleaner brands. Ionization - it does have some air cleaning effects but ionic air cleaners work slowly and rely on the natural air currents/flow of your house.

INFO LINKS Air Purifiers Overview - view all air purifiers sold by AllergyBuyersClub.com Air Purifiers Comparison Chart - a comparison with pluses and minuses of all the best air purifiers Pollen and Hayfever Solution Guide - a quick buyers guide of the best recommended products to solve airborne allergen problems Best Air Purifier Articles - Editor's top picks on air purifier info

If you have an airtight house, an ionic air cleaner is best used in the presence of a fan. Ion air cleaners drive particulates to stick to surfaces known as the "black wall effect". The big plus of ion air cleanersis they are silent and cheap to maintain. Personally, I think the added benefit of ionization is best used in what we call combination machines which also have collection plates to avoid the black wall effect. Hepa filters - very efficient but tend to be noisy as they have big fans, degrade over time and most machines do not tell you when the hepa filter needs replacing. I bet most people with hepa filters have ones which are almost useless, because the hepa filter needs replacing and they do not know it. How often does it need replacing? - Well as they say, that all depends as to whether you have it running a few hours at night in pollen season in your bedroom or run it all day and night.

My other pet peeve is most of these hepa air filters don't tell you when you have perfectly clean air and don't need to continue to run the filter. This is clearly a waste of electricity and wears the filter out earlier. Smart sensors, telling you when to change air filters, do not come with most air cleaners.

The other thing about hepa filters is you should make sure the filter is true hepa - there are many cheaper- hepa-like filters which are cheaper [better than nothing] but are not so effective, and the question answered here was about "best". The other thing to look for in hepa air cleaners is the CFM rating. A higher number means more air changes per hour or the machine covers a bigger area. In other words, 400 CFM is a more powerful air cleaner than one rated at 250 CFM.

What difference does that make you ask? Well, vendors routinely overstate the effective cleaning area of an air cleaner because the area is calibrated at the machine's high fan speed. Now, try to sleep with that fan on high - it sounds like a train going through your bedroom. Reality is that you need 4 air changes per hour for health reasons, and low fan speed is the only level comfortable for sleep. So you need a pretty powerful air cleaner to accomplish that objective, more in the 350 to 400 CFM range.

We have not done formal long term testing of the ultra violet air cleaners, but the lab testing data we have on some of these newer machines looks very compelling. We have also tested electrostatic air cleaners, and they are not so efficient, but much quieter and cheaper to maintain as you just put the collection plate into the dishwasher. We would add the proviso that disassembling and reassembling the air cleaner is simple for the mechanically oriented and a bit daunting if you are not.

IQAir and Blueair probably are your best bets. Allerair and Austin as runners up. To my mind, there is no perfectly designed air filter YET. There are filters that do the job. I don't have the space here to give you the pros and cons of each of these machines but I hope this helps. BTW we use the Blueair in our own bedroom - it is quiet - or relatively speaking.

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First Published: February 2000
Updated: April 2007

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