Portable air purifiers are the most commonly sold variety of purifier, although some modern central air conditioning systems have built-in air purifiers. Purifiers typically fall into one of three categories: HEPA (High Efficiency Particulate Air) filtration, negative ion generation and electrostatic precipitation.
Some air purifier models specialize in removing errant smells and odors caused by cooking or pets while others concentrate on eliminating fungi, bacteria and other alleged health-threatening toxins from the air. Some models combine features of all of the purification technologies to remove all harmful substances from the air that may cause health problems, physical discomfort or irritation.
If persons in the household are especially sensitive to airborne chemicals, be sure that the selected purifier does not emit any gases during its operation. Also check to see if the selected model is recommended to operate in areas that already have air conditioning units installed.