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What to Look for in Air Purifiers

The manufacturers of air purifiers can make all sorts of claims about what their machines will do. Some of those claims are accurate; others have questionable veracity. Here is a short guide to what you should look for as you shop for an air purifier.

HEPA, CADR and Other Buying Considerations

  • Your best defense against bad air indoors is to amp up your heating and air conditioning unit’s filtration system. This will clean the air throughout your house, not just in one room, as many air purifiers do (that is all they are capable of!). A filtration module can get into four figures in terms of cost, but they are a good option for those who are very serious about their indoor air quality. They will need to be professionally installed and connected to your home’s electrical system as well.
  • If an air purifier is to work well it will need a fan to suck in air to be cleaned. In consumer tests, air purifiers with fans out-performed those that lacked fans.

HEPA filter

  • The best portable air purifiers that you can buy have a HEPA (High Efficiency Particulate Air) filter. These are the gold standard of air filters, trapping 99.97% of all air particles. Look for HEPA filters in any type of air purifier that you buy. Replacement HEPA filters run between $40 and $150. Some newer models have washable HEPA filters.
  • Electrostatic purifiers don’t use filters at all. Instead they utilize an electrically charged plate to capture pollutants. These machines do emit ozone, which can be an irritant to those with respiratory ailments. These plates need to be cleaned about once a month.
  • It is wise to get an air purifier that has some sort of indicator light for when the filter or plate needs cleaning or replacement.
  • You want to be sure that your air purifier is suited for the space that you want to purify. Measure the room or rooms that you want to impact and then check the coverage area of any machine that you buy. No portable air purifier can work effectively throughout your home, unless you live in a studio apartment.
  • If you run a fan in an air purifier at its highest speed, you will generate a good bit of noise. It’s best to buy a machine that is too large for your room and run it at a low fan speed for reduced noise. The differences in price are not large.
  • Air purifiers are measured according to Clean Air Delivery Rates (CADR) that indicate their power and effectiveness. These numbers range from 10 to 450. A 250 CADR=adding 250 cubic feet of clean air per minute, for example. Consumer tests indicate the best air purifiers have a rating of 300 CADR or above.
  • Many air purifiers use multiple filters and some add baking soda or UV lamps to amplify their abilities. The exterior filter inside the machine (often called a pre-filter) traps large particles while the interior filter takes care of the rest. The inner filter is often a HEPA filter. Baking soda is sometimes added to the pre-filter to help with odor prevention. The top-rated air purifiers have this multi-filter system.
  • Air purifiers are usually fairly small, but if you are not too strong you might want a machine with wheels. Many models come with handles as well for easy movement.

Do You Really Need It?

However, it is wise not to over-estimate the effectiveness of an air purifier. Common sense dictates that the best air purifying you can do is to open the windows and doors and let fresh air flush out the stale air in your living space. If the weather is bad and prevents that, or you have conditions that can produce unusually poor air (smoker, humid conditions, pets, etc.) than an air purifier might be right for you.