What do you think? Are indoor air purifiers just another expensive dust collector? The irony being you buy them to collect dust, right? Of course, you really should expect far more of your indoor air purifier than a Hummel figurine collection. For instance, protection from infectious diseases like the swine flu comes to mind.
What options do you have for combating microbes: germs, viruses, bacteria, and mold spores
What does it take to neutralize these little beasts? You have two options: Kill or Contain. Or maybe a little of both.
Killing means UV light. Preferably UVC, a more energetic wavelength and thus more deadly. Microbes in the air passing by a UV lamp may be killed outright but if not, they stand a good chance of being genetically damaged to the point of being unable to reproduce.
There are a few other promising options for killing. Some involve silver treated filters, hydroxyl radicals as in the so called plasma air purifiers. Even titanium dioxide coatings inside indoor air purifiers seem to have a killing effect. Of course, TiO2 coatings are activated by UV light.
Containment is only possible with a true HEPA filter. Preferably in a tightly sealed model with demonstrated total system efficiency close to the HEPA filter's theoretical efficiency. A good model to consider is any of IQAir's HealthPro series. In fact, IQAir air purifiers were exclusively chosen to assist Hong Kong hospitals during the SARS virus outbreak a few years ago.
The benefit of the containment route is a higher degree of removal from the air. With UV light some microbes may pass too far from the UV lamp or even be riding on the shady side of microscopic particles, thus dodging the bullet.
Certain air purifier models offer both high system efficiencies and UV light in combination. You may wish to consider them also. Allerair manufactures a variety of excellent indoor air purifiers with a UV option. NQ Clarifier comes with both HEPA filtration and UV.