|Why Consider Air Purifiers, Filters and Cleaners?|
Types of Available Air Purifiers And Filter Systems
Until recently, small, inexpensive, table top appliance-type air purifiers have typically been quite popular in terms of unit sales. They generally contain small panels of dry, loosely packed, low-density fiber filters upstream of a high-velocity fan.
Table top units may also consist of a fan and an electronic or other type of filter.
Room Units - Recommended
Another major type of residential air purifiers is the larger, yet portable, devices designed to remove pollutants in a specific size room. Due to their larger and more effective filters or collecting plates, these larger portable filters are considerably more effective in removing pollutants in a room than the table top units (Consumer Reports, 1992; Fox, 1994) and have become increasingly popular in the past several years.
The highest efficiency for smoke and dust removal was observed in a room unit utilizing electrostatic precipitation. Portable room units are much more effective in rooms where all doors and windows are closed (AHAM).
Central Filtration Systems
Filtration systems can also be installed in the central heating or air-conditioning systems of a residence or in an HVAC system. These units are commonly referred to as "in-duct" units, although this term is actually a misnomer since they are not located in the distribution ductwork, but rather in unducted return circulation grilles.
A review by Fox (1992) suggests that a highly efficient room unit will be more effective at removing pollutants in the room where it is located than a central filtration system. Consumer Reports (1992) also recommends that for removing pollutants in a room or several rooms, a portable filtration system is more effective than a central system.