Austin Air HealthMate

Reviewers agree that the Austin Air HealthMate is a powerful machine, capable of cleaning a 1,500-square-foot room. It filters larger allergen particles such as dust, pet dander, pollen and mold spores with its HEPA filter, and Austin Air says its carbon filter captures 95 percent of the tinier particles that make up chemicals and odors in the air, down to 0.1 micron -- although the HealthMate doesn't claim to remove particles as minute as the pricey IQAir HealthPro Plus (*Est. $900) can tackle (down to 0.003 microns).

Besides the HEPA and carbon filters, the HealthMate also uses two prefilters -- but unlike most other air purifiers, you don't have to change one filter or another every few months. All of the HealthMate's replacement filters come in one pack (*Est. $180), which you change once every three to five years. Unlike other companies, Austin Air's five-year warranty covers not only the machine, but also the filter. Weighing 45 pounds, the boxy HealthMate is relatively heavy compared with other air purifiers (it includes wheeled casters for easier moving). Austin Air does offer a smaller model, the Austin Air HealthMate Jr. (*Est. $300), which is designed for smaller rooms. The only real complaint we found about the HealthMate in expert and user reviews is the noise. The HealthMate registers about 50 decibels (about the same as quiet conversation) on its lowest speed, which some experts consider too loud for bedroom use, although several users say they have no problem sleeping or watching movies with the HealthMate running on low.

The Austin Air HealthMate is rated by ConsumerReports.org, but results there do not match those at other sources, perhaps because ConsumerReports.org's tests judge air purifiers more on speed than long-term effectiveness. Knowledgeable experts at AllergyBuyersClub.com and Air-Purifier-Power.com agree that the HealthMate offers great value, an opinion backed by the handful of user reviews at Amazon.com.