Portable air cleaners, especially when used in the bedroom, are a mainstay of allergy treatment. Eliminating or decreasing your exposure to allergens which cause allergies of the nose, sinuses or lungs (allergic asthma), are essential to how comfortable you will be and may lessen the amount of medication that you require. The two most popular brands of portable air cleaners are the HEPA (High Efficiency Particulate Air) cleaner and the air precipitator cleaners (nonHEPA).

Michigan Allergy, Sinus & Asthma Specialists believe that the HEPA filters are much more effective than the precipitator filters.

The filter is one of the key components of an air cleaner. Filter types are defined by the size and number of microscopic particles that they remove from the air passing through them. Microscopic particles are measured in microns. The period at the end of this sentence is approximately 400 microns in size. Pollen grains are 30 microns, dust mite waste particles are about 20 microns, and cat allergen particles vary from about 1 to 20 microns in size.

A HEPA filter removes 99.97% of all particles as small as 0.3 microns from the air that passes through it. But note that these percentages refer to the air that passes through the filter, not necessarily to all of the air in the room. Many advertisements give the misleading impression that any HEPA filter will clean the air in a room of more than 99% of his particles. The reality is that the amount of cleaning of the air in the room depends not just on the filter, but on the amount of air movin through the filter. This is expressed as the "clean air delivery rate" or CADR. Both the EPA and the American Lung Association recognize CADR as the appropriate test of air cleaner effectiveness.

Air cleaners are usually advertised with the room size for which they are recommended. Keep in mind, however, that this recommendation is based on the unit's ability to provide five or six air changes per hour in a room of that size. That rate is sufficient to decrease particle levels in the room by about 70%. A larger unit in the same size room can produce eight or more air changes per hour, decreasing levels by 90% or more. This is the correct target in medical situations.

Another point to consider is that many popular air cleaners are designed such that the clean air is blown downwards onto the floor. This has actually been shown to blow allergens from the floor (especially if it is carpeted) into the air, thus negating the effect of the filter! We would therefore recommend that you purchase an air cleaner that does not exhaust the clean air downwards.

With regards to ionizing, precipitating air cleaners, we do not feel that they are as effective as HEPA filters. They have been advertised as being more stylish in appearance, quieter and not needing filter replacement. The May 2005 issue of Consumer Reports has an article evaluating ionizing air cleaners.

The following statements are taken from the May 2005 issue:

Buying an air cleaner that doesn't clean the air is bad enough. Some of the least effective ionizer models also can expose you to potentially harmful ozone levels, especially if you are among the roughly 80% of buyers with asthma or allergy concerns.

Also known as electrostatic precipitators, the ionizing air cleaners we focused on for this report are supposed to trap charged particles on oppositely charged plates. But as we reported in October 2003, models like Sharper Image's Ionic Breeze, the market leader, did a poor job removing dust and smoke from the air. Our latest tests also show that some ionizing models can expose you to significant amounts of ozone.

Air cleaners do not need to meet ozone limits not for the Federal Environmental Protection Agency which regulates only outdoor air nor for the Food and Drug Administration, since the FDA does not consider air cleaners to be medical devices despite the health benefits that some of the manufacturers' ads imply.

Consumer Reports ran tests to see if the air cleaners produced more ozone than 50 parts per billion (a voluntary standard that both manufacturers and the FDS use for medical devices). This was done by using a steel polyethylene room and measuring ozone levels two inches from each machine's air discharge in accordance with the EPA standard. Five ionizers were measured and all five failed the test by producing more ozone than the 50 parts per billion over 24 hours.

These ionizing air cleaners were:

1. Sharper Image professional series Ionic Breeze Quadra 51 737SNX.
2. Ionic Pro C 369.
3. IonizAir P4620.
4. Surround Air AR XJ 2000.
5. Brookstone Pure Ion V2

It is generally agreed that increased ozone concentration, over 80 parts per billion for over eight hours can cause coughing, wheezing, chest pain and can aggravate allergies. In addition, while ozone dissipates indoors, it can create other pollutants in the process. Research suggest that ozone reacts with the terpenes in lemon and pine scented cleaning products and air fresheners, creating formaldehyde -- a carcinogen -- and other irritants. Those byproducts can be absorbed by beds and carpets, and be released over an extended time period. Research has also found that ozone reacts with terpenes to create additional ultrafine particles, which are hard to filter and can go deep into the lungs. We suggest that you review the entire article published in the Consumer Reports May 2005 issue.

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Michigan Allergy, Sinus & Asthma Specialists

6330 Orchard Lake Road #110 West Bloomfield, MI 48322 Tel: 248.932.0082 Fax: 248.932.0182 view map

37595 Seven Mile Road #320 Livonia, MI 48152 Tel: 800.739.6100 Fax: 248.932.0182 view map

Web: www.michiganallergy.com
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