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By James Dulley, Published December 11 2009

Filtering materials key to effective air cleaners

Dear Jim: Several of my children have allergies, so I want to use room air cleaners in their bedrooms. I have seen many advertisements with great claims for effectiveness. What type of room air cleaner is really best?

– Randy R.

Dear Randy: It can be quite difficult to separate the truth from the advertising hype about the effectiveness of various room air cleaners. The sheer size or price of a specific unit does not necessarily indicate it is effective. The type of filtering material inside is what is most important.

For the most effective air cleaning, particularly during winter, it is wise to use both a high-quality central furnace air cleaner along with room air cleaners. Some of the newer central air cleaners are very effective, but they remove only the particles that actually get into the duct system.

When your children plop down on a sofa or walk on the carpeting, a cloud of allergen particles comes up. Some of these particles are relatively large and settle out of the air before they ever get near the furnace return air registers. A room air cleaner can remove many of these particles.

Instead of relying on advertising information, use the CADR (clean air delivery rate) rating to compare various air cleaner effectiveness. This rating is determined by testing procedures sanctioned by the Association of Home Appliance Manufacturers. The U.S. Environmental Protection Agency and the American Lung Association recognize the CADR data as accurate and realistic.

The first step is to have your children tested to determine what airborne allergies they have. This is because the effectiveness of different designs of air cleaners and filtering methods varies depending upon what particles you need to remove from the room air.

Three of the most common types of particles in room air are household dust, tobacco smoke and pollen. These cover the size range of most other typical airborne particles. The CADR ratings have three separate numbers that refer to these three particles. You may find an air cleaner that is very effective for pollen but not as effective for tobacco smoke.

When selecting an air cleaner, the CADR indicates the maximum size of room for which the air cleaner will be effective. A guideline is the CADR rating for the specific particle of interest should be at least 2/3 the square footage of the room. For example, a 10-by 10-foot room would need a CADR of 67 or greater.

In general, I prefer a HEPA filter media with a carbon element. A HEPA filter is effective for almost all sizes of common allergens, and the carbon removes odors and chemicals. A large carbon element is best. Select one with several fan speeds for rapid air cleaning before bedtime and quiet slow-speed operation at night.

The following companies offer room air cleaners: Blueair, (888) 258-3247, www.blueair.com; Cloud 9, (630) 595-5000, www.4cloud9.

com; Essick Air Products, (800) 547-3888, www.essickair.com; Kaz, (800) 447-0457, www.kaz.com; and LakeAir, (800) 558-9436, www.lakeair.com.

Dear Jim: I need some additional insulation in my attic, and I plan to use fiberglass batts. It will

require quite a bit of cutting and fitting. What is a good way to cut fiberglass insulation crisply and straight? – Sean M.

Dear Sean: You are correct in trying to get a tight fit of the batt insulation without many gaps on your attic floor. Just several gaps can reduce its efficiency gains. Always wear gloves and a breathing mask.

Get a piece of scrap plywood that is longer than the insulation width and saw a narrow slot in the plywood. Lay the plywood over the insulation to compress it and then run your knife through the slot for a straight cut.

Send inquiries to James Dulley, The Forum of Fargo-Moorhead, 6906 Royalgreen Drive, Cincinnati, OH 45244, or visit www.dulley.com