Electronic air cleaners: energy efficient, no costly filter replacement and good cleaning capacity

Electronic air cleaners, also commonly known as air ionizers or ionic air cleaners, represent good value for money. They are mostly silent, energy efficient, and since in most types no expensive filter needs to be replaced, cheap to run. But you have to pick the right type.

There are essentially three types of electronic air cleaner: negative ion generators, electrostatic precipitators, and electrostatic filters.

Negative ion generators give air molecules an additional electron, and thereby become negatively charged.
Their negative charge causes airborne particles such as dust, pollen, smoke and dander to cling to each other. The larger particles become too heavy and they settle on the floor, where they have to be vacuumed, otherwise they will be kicked back into the air through movement.
No fan is used, so this type of air cleaner is quiet, but it also means that the negative ions have to circulate the room on their own. And because negative ions have a short lifespan, only the immediate vicinity of the ion generator is allergen free.  So before you buy that nice looking model, it's a good idea to check the manufacturer's specifications to find out what size room it can clean.

Electrostatic precipitators are a more effective type of ionic air cleaner. The incoming air particles are first negatively charged, and then drawn between positively charged plates. Because of the opposite charge the particles attach themselves on the plates. The plates have to be cleaned periodically otherwise they quickly loose their effectiveness.
The Friedrich C-90A Electronic Air Cleaner uses electrostatic precipitators, and was recently rated best in the Nation's largest independent consumer review magazine. The well known Ionic Breeze also incorporates this technology.

Finally, there are ionic air cleaners on the market that instead of plates use a positively charged filter, also called an electrostatic filter, to collect particles.  With these filters it is also important to clean them on a regular basis. 
As an example, Hunter air purifiers use an electrostatic filter in their air cleaners combined with, among others, a prefilter and ionizer.

Negative ion generators and electrostatic precipitators have quite a few benefits:

• No filters that need replacing.
• Energy efficient
• Constant airflow
• Not noisy

And last, bust certainly not least, ionic air cleaners can trap particles as small as 0.05 micron, which means that virtually all allergen are trapped.

Be aware though, that most air ionizers release trace amounts of ozone as a by-product, and some people don’t like it’s smell. On the other hand, ozone is very good at neutralizing odors, so on balance most people consider it a plus.

Of the three types of air ionizers, the negative ion generator is the least effective by itself, and we can not really recommend them.
However, in combination with other air purification methods the picture changes. For instance, in the Oreck Super Air 8, the negative ion generator is used to refresh the air as the last phase in a 5 stage cleaning process.

Electrostatic precipitators and electrostatic filters are quite effective, and are often combined with other air cleaning technologies, resulting in a better all-round hybrid air cleaner.
For instance, the well known Ionic Breeze model consists of a UV germicidal lamp to kill viruses and bacteria, and an electrostatic precipitator to capture dust, pollen, smoke, mold spores etc.
Likewise, the Oreck Super 8 comprises a prefilter, electrostatic precipitator, activated charcoal, and a negative ion generator, so that it can effectively cover pollutants and allergens of all sizes.

The Sharper Image - Ionic Breeze
The Asthma and Allergy Foundation of America awarded the Consumer Product Seal to the Ionic Breeze Quadra and GP air purifiers, because they are "proven to reduce airborne allergens and irritants including dust mite allergen, pet dander and cigarette smoke'."