Air Filters: Do They Work?

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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.