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How to Select Filters
After you have successfully
isolated and eliminated the pollution sources per the recommendations in last month's tip, you are now ready to filter the air. Yeah!
Most homes with central heating or air conditioning have air filters in the
ductwork near the
mechanical equipment. The standard air filter is a 1" fiberglass panel filter, and costs only a few dollars. These filters remove most of the large dust particles, however, they are not very effective at removing most contaminants from the air.
To determine filter efficiency check the MERV rating, which rates a filter based on the percentage of particulates of various sizes that it removes from the air. A filter can be rated with a MERV between 1 and 16. A higher MERV rating indicates a more efficient and
effec
tive filter. The American Lung Association's
Health House recommends filters with a minimum MERV rating of 10.
Types of Filters
Pleated filters
are basically fiberglass panel filters that have been pleated or folded to provide more surface area, which makes them more effective at collecting particles. Pleated filters cost between $10 and $30, and can be found at most hardware and home improvement stores. Look for the MERV rating to determine the effectiveness of the filter. Pleated filters with a MERV rating of 10 can cost as little as $15.
High efficiency pleated filters
use an electrostatic charge to capture small particles and allergens. They are more effective than pleated filters at removing particles such as dust, pollen, mold and pet dander.
Washable/reusable filters
are designed to be washed and reused. They never get completely clean, so eventually they can become restrictive to air flow. The American Lung Association says that these filters are ineffective at capturing small particles.
Electronic air cleaners
(also called precipitators) use an electrical field to trap charged particles to a collector plate that has an opposite charge. Unlike the high-efficiency pleated filters, which use a passive electrostatic charge, electronic air cleaners use electricity to generate a charge on particles. They are effective at trapping particles of all sizes. It is extremely important that the collector plate gets cleaned regularly because they lose their efficiency as dirt collects on them.
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It is important to change or clean air filters on a regular basis because filters get clogged with the dust and contaminants they collect, which restricts the airflow. When airflow is restricted, it forces the fan(s) in the air handler to work harder, increasing your energy bill, reducing the life of the air handler, and even increasing its noise level. Follow the manufacturers instructions on the filter and your HVAC system. Most filters need to be replaced every three months. |
High efficiency particulate air
(HEPA) filters are thick filters that remove even very small particles very effectively. HEPA filters often don't fit most existing central systems. They typically need a separate filter housing system that is designed specifically to accommodate HEPA filters.
UV filters
use ultraviolet rays to kill bacteria, fungi and viruses. Like HEPA filters, UV filters don't fit into most central air systems. UV filters do not eliminate spores, which are more resistant to UV than most bacteria, but spores can be removed by a high-efficiency filter. For this reason, UV filters should be used in tandem with high-efficiency filters. UV filters are often used in tandem with HEPA filters, however a study by Pennsylvania State University found that HEPA filters do not remove significantly more microbes than less expensive high-efficiency filters when used in tandem with UV filters, so HEPA filters are not worth the extra cost
Ozone generators
produce ozone in an attempt to control indoor air pollution. However, ozone generators should not be used in homes. The
Environmental Protection Agency has found that at healthy levels ozone is ineffective at improving indoor air quality and in high concentrations ozone can cause health problems, including lung damage.
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