How To Select An Air Purifier
by Dr. Terry Stanger, M.D. Tarzana, CA

(Dr. Stanger practices Internal and Family Medicine in Tarzana California. This article was originally printed in the Los Angeles Daily News in November, 2004.)

 Introduction

If you live in Southern California, you should consider purchasing an effective air purifier. It is important to research your purchase decision because some air purifiers are effective and some simply aren't. While some are easy to maintain, others are so difficult or expensive to maintain that people stop using them.

The EPA has stated, and recently published studies confirm:

  • Southern California air is terribly polluted. It's ranked worst in the nation.

  • The air is full of dangerous tiny particles that affect our health — especially the health of children and seniors.

  • Indoor air purification using HEPA filters can be effective at combating these problems.

    Air Cleaning Methods:

    1. Fan or fan-less? Purifiers with fans draw in air from around the room, purify and then widely recirculate the cleansed air. Fan-less purifiers attract only a small nearby volume of air toward internal dust collection plates, which must be cleaned every week or two. Consumer Reports tested and found a famous fan-less purifier to be "ineffective" at cleaning the air.
    2. Filters. All filtering purifiers use fans and most use only one or two of three common filter types.
      • Activated Carbon filters are used to remove chemical vapors, gases and smoke - such as from cigarettes and candles.
      • HEPA filters remove tiny particles, pollen, mold spores, bacteria and viruses, pet dander, dust and dust mites.
      • Pre-filters are not used in all air purifiers, but when they are, they trap the largest particles, allowing the other filters to work better and last longer.
    3. Ultraviolet Light disinfects the air passing through the purifier and any filter-trapped particles.
    4. Ozone neutralizes odors and disinfects the surrounding environment to some degree.
    5. Ionization electrostatically charges molecules, which transfer their charge to other particles on contact. Charged particles clump with oppositely charged particles making them large and heavy enough to either be trapped in a filter or too heavy to remain suspended in the air.

    Here's what you need to know to select a good air purifier:

  • To eliminate airborne particles, you need HEPA and pre-filters. Ionizers boost their performance.

  • To remove gases, chemicals, odors and fine smoke you need an activated carbon filter. Controllable ozone can also help. Not all ozone purifiers allow you to adjust ozone flow or turn it off. There are times when you want ozone and times when you do not.

  • Ultraviolet light and ozone destroy mold and germs.

    Maintenance

    Maintenance is a major concern. Some purifiers need an occasional filter or UV bulb change and nothing more. Others require astonishingly intricate disassembly routines to clean ionizing plates and wires. Almost every vendor will tell you that their purifier is easy to maintain, but a look at the user manuals reveals the truth. Before buying any purifier, read the user manual, which should be available from the manufacturer's web site!

    Units that claim to be maintenance-free or have 'nothing to clean or replace' are not appropriate in Southern California. Simply put, they do not remove particulates from the environment.

    Coverage

    Some air purifiers claim to clean your entire home. Others cover less space. Be aware that purifiers that claim to clean large areas don't work through walls. You must leave your doors open to treat other rooms. Their effectiveness decreases, as you get further away from them. It's better to use several smaller, quieter units instead of one large noisy unit.

    Try it out

    When you decide on a purifier, make sure it has a satisfaction guarantee. Buy it and use it for a few weeks to see and feel the results.

    Summing up:

    Most air purifiers use one or two of the cleaning methods described above. Some use more, or even all of them. If you live in Southern California there's every good reason to believe that you will benefit from using an effective air purifier in your home and office.

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