Air Filters: Do They Work?

Finding the right air filter can be a challenge. This guide aims to change that.
February/March 2001
http://www.motherearthnews.com/natural-health/air-filters-do-they-work-zmaz01fmzsel.aspx
Air filters can be a difficult item to shop for.


Photo courtesy MOTHER EARTH NEWS editors

One of the challenges, if not the challenge in buying an air filter is that there is no one way to judge performance. A dozen manufacturers include the AHAM (Association of Home Appliance Manufacturers) test sticker and/or logo, which often a measurement of airflow in cubic-feet per minute. The faster the flow, the more rapidly room air is cleaned. How well the air is cleaned is another matter entirely. AHAM advises buying a unit with a CADR (clean air delivery rate) that is two-thirds the square foot measurement of the room you would like cleaned, provided that the ceiling is not exceedingly high. A 20' x 10' room, then, would need a CADR of about 140. Also, frequently seen on both portable and whole-house filters and inserts is information from ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers). ASHRAE certification offers a more informative measure of cleaning, in terms of "efficiency," or the percentage of air contaminants effectively filtered by the appliance.