Air Purifiers

Air purifier types to consider

Keeping our homes tightly sealed for comfort and warmth also means trapping considerable amounts of air pollution indoors. Air purifiers can help to remove harmful germs, bacteria, odors and other substances that cause health risks most homeowners aren't even aware of. Purchasing the most appropriate air purifier for your needs is the first step to improving the air quality in your home.

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Mechanical vs. Electronic Air Purifiers

The air purifier you buy will depend on the major pollutants you want to target, the efficiency you want and the level of maintenance you're willing to commit to. Air cleaning devices can be classified as mechanical, which requires filters to collect particles, or electronic, which uses charged particles to attract and capture pollutants. Mechanical filters include HEPA-certified units, UV filters and carbon filters, while electronic models may be ionic, ozone or electrostatic. Electronic air filters can be highly efficient, but they also release ozone into the air, which irritates lungs and can be especially damaging for individuals with asthma and other respiratory diseases.

Prices for air purifiers vary widely, so it is more important to pay attention to the performance information listed on the packaging. While it is difficult to make standard assessments of electronic air cleaners, the efficiency of mechanical filters is measured using MERV ratings, ACH ratings and clean air delivery rates (CADR).

MERV ratings are an indication of how effectively a cleaner captures particles of various types and sizes; ratings range from 1 to 16, with higher numbers indicating greater efficiency. The ACH number (air changes per hour) offers a specific assessment of how often the device can completely exchange the air in the room. This is especially important because matching the purifier to the size of the room (measured in square footage) determines its overall performance. CADR ratings indicate the rate at which air is purified.

Remember to check that the product includes a "sealed" or "controlled" system in order to prevent impurities from leaking back into the air. You may also want to ask a salesperson about the noise level or stick to stores with operating floor models so you can hear them in action. Most people use air purifiers in the common areas of their home — living room, kitchen and bedrooms — so quiet operation is a must to prevent interruption of daily activities.

Types of Air Filters

Purifiers are only as useful as the air filters they employ. The following is a list of six major filters you're sure to encounter when shopping for an air cleaner:

  • HEPA. Certified HEPA air purifiers are effective against 99.7 percent of airborne particles as small as 0.2 microns, including mold, dust, pet dander, pollen and fungi. They can also include additional antibacterial agents to fight bacteria and germs. HEPA filters must be changed periodically.
  • Carbon. Carbon filters use chemical bonding to eliminate lingering gases, odors and harmful organic compounds found in cleaning supplies, aerosols, varnishes and other common household items.
  • Ultraviolet. UV air purifiers are frequently used in medical settings because they eliminate microorganisms and sterilize many types of bacteria and mold.
  • Ionic, Ozone and Electrostatic. While all electronic cleaners use charged particles to capture pollutants, ionic air purifiers cause the materials to cling to a nearby surface, sometimes resulting in dark stains on walls or floors. Electrostatic filters operate similarly but collect materials on washable filters that don't need to be replaced. Ozone air purifiers are chiefly limited to eliminating odors and mold. The effectiveness of these devices is questionable, and some may be banned in certain areas due to ozone emissions.

Almost any product will be an improvement from normal air quality, but multifunctional purifiers are most effective, combining multiple filters to target various pollutants. For the safest, most beneficial system, focus on HEPA-approved purifiers that include a carbon filter so you'll have all the bases covered.