Advertised Square Footage...

Advertised numbers are often exaggerated to make the sale. You can see that with car sales where mileage usage and horsepower are often exaggerated. This is also true of air purifiers.

Most often this is seen with HEPA air purifiers. Remember that these air purifiers must draw the air through to purify. To do this in a large house is difficult, in a two story house - almost impossible. The reason is that the air has to circulate around the house to do this; moreover, if windows are open the volume of air is effectively increased further.

what to do? Use HEPA air purifiers in areas under 1000 sq. ft. and generally under 400 sq. ft. for best results and run the units continuously.