A stream of sunlight coming through a window will reveal the dust floating in the air. That dust not only winds up on floors and furnishings, it is also the bane of many allergy and asthma sufferers.
The air filter in your furnace helps take dust out of the air, but it is important to know that some filters work better than others. Typical filters, for example, are only about 15% efficient and provide little help. In contrast, a HEPA filter can remove up to 99.97% of air-borne contaminants .3 microns (.0003 inches) or larger.
The most efficient, whole-house air-cleaning system is one that uses a HEPA filter equipped with a Genteq motor (see illustrations at left). This HEPA unit is three filters in one: the top polyester filter removes larger; visible particles; the charcoal filter removes the most minute respirable particles from the air passing through it. The HEPA my also be set up to bring in outside air through an ERV it is powered by a Genteq motor which means you can clean the air continuously for pennies a day.