Humidifiers add much-needed moisture to dry air, but most do little to improve indoor air quality. While air purifiers can remove contaminants like smoke and dust from the air, these appliances do little or nothing to increase humidity. To combine these two features in a single unit, look for airwashers, or humidifier-purifier combo units. Airwashers allow you to avoid the costs associated with two separate units and free up floor space for other uses.
Buying an Airwasher
As of June 2013, several manufacturers make airwashers that combine a humidifier and air purifier into a single device. Venta, Air-O-Swiss and Beurer produce models that don't require filters, while Honeywell and Sharp make airwashers that incorporate filters to clean the air. The Sharp model includes a high-efficiency particulate air filter, which promises to remove 99.7 percent of particles as small as 0.3 microns.
How Airwashers Work
Airwashers feature one of two basic operating systems. Some draw air from the room into a filter, which traps dust and pollutants. The clean air then gathers moisture from a tank in the machine and carries it back into the room using a cold evaporation process. Units without a filter draw dirty air in from the room, and a fan directs this air through a series of rotating disks. As the disks rotate through a tank of water, any dust or other particles are left on the disks or in the lower housing of the unit, and the purified air carries moisture back into the room. Some units equipped with disks also incorporate ionization technology, which charges pollution particles as they enter the airwasher. This charge helps attract particles to the disk and keeps them from blowing back into the room.
Filters and Cleanup
Airwashers with filters generally include washable filters for easy cleanup and lower maintenance costs. You simply remove the filter and wash away particles and dust before replacing it in the unit. If the unit doesn't have a filter, you simply empty out the water and wipe off the disks and the inside of the tank to remove dust and pollutants that have collected inside.
Buying an airwasher requires sizing the unit to the room, just as you would with separate air purifiers and humidifiers. Many of these units are rated to humidify a much larger area than they are designed to purify, so choose a unit that can accommodate your needs in both of these categories. When reviewing one airwasher, "Consumer Reports" warned that it had no noticeable affect on air quality, so choose a unit designed to capture the smallest possible particles to improve the odds that your airwasher will effectively clean the air. "Consumer Reports" also criticized the lack of a humidity control on the airwasher being reviewed and recommended that consumers choose a unit with a built-in humidity control setting.