Free of the health hazards of ozone: Ionizers, negative ion generators, and electrostatic precipitators generally produce ozone. Ozone is a toxic pollutant, that is on various indexes of air pollution. The way to know for sure if an air purifier is free of ozone, is if the company states it is ozone free. Vitaire's stated position is very clear: Vitaire HEPA air purifiers do not produce ozone, and are free of ozone.
Be wary of many air purifiers, that do not list a percent efficiency: If an air purifier does not list a percent efficiency, it could be any efficiency, including 80%, 50%, 25%, 10% or even only 1% efficient. Lower efficiency air purifiers tend to remove less allergenic particulates. For allergy or asthma related to allergenic particulates, it is important to have a higher efficiency to remove more of the allergenic particulates. Vitaire air purifiers have an efficiency of up to greater than 99%.
Be wary of many air purifiers, that may list a percent efficiency, but do not list the test method: If an air purifier lists a high efficiency of 90%, but does not list the test method, it is still very difficult to know, what the air purifier is actually removing. To illustrate, using an exaggeration to make a point: If the particulates were golf balls, and they were tested against a window screen, the screen would be 100% efficient at removing the golf balls. But in terms of removing allergenic particulates, the window screen would be almost useless. On the other hand, the efficiency of Vitaire air purifiers is based on the NBS Dust Spot Test in atmospheric air. NBS stands for National Bureau of Standards. Atmospheric air means real ever day air, that we breathe, not artificially large particles (like golf balls).
1 Different units may not be as illutrated, and may
have different characteristics and different performance, depending upon unit
and motor design, as well as airflow location, directions & velocity, as well
as room size and layout, as well as particle types, sizes and materials, as well
as air movement or drafts within the room, that are or are not related to any
unit.