High-Grade Furnace Filters Cost More but Last Longer

If you have forced-air heat, it’s almost certainly time to change your furnace filter.

Standard paper-rimmed fiberglass filters (about $2) need replacing once a month during heating season.

But before you make the replacement, there’s something you should know:

These filters are designed to keep your furnace’s heat exchanger clean and efficient, not to clean the air so you breathe easier. They aren’t effective at trapping the small particles that harbor bacteria, pollen, mold, dust mites and other irritants.

If someone in your family is prone to respiratory ailments or allergies, you might want to consider a higher-performance filter.

These products, which are designed to replace your existing filter and must be the same size, cost from $15 to $100 or more, depending on design.

They’re widely available, including from mail-order and Web-based sources such as:

* Airsponge Filter Co., (800) 757-1836, https://www.airsponge.com;

* Cistal Enterprises, (800) 724-2220, https://www.oxyclean.com;

* WEB Products, Inc., (800) 875-3212; https://www.webproducts.com.

However, most filters share basic features. They’re made so airflow through the filter creates a slight electrostatic charge that attracts and holds airborne particles.

Although filter designs, materials and claims differ, these types of filters will trap up to 85% of particles in the 3- to 5-micron range (1 micron is 1/25,000th of an inch).

Most also contain an antimicrobial additive to help control mold, mildew and bacteria. Some filters also offer an optional activated-charcoal screen, which helps with odors and cigarette smoke.

Most high-performance filters are washable, and with proper care they can be used as long as 10 years.