Should I buy an air purifier for my asthma and indoor allergies?

Attention asthma and allergy sufferers! Has your doctor suggested buying an air purifier for your house to help reduce asthma and allergy symptoms? Here are some Q & A to assist you.

Q: What is a HEPA air cleaner?

A: HEPA stands for “High Efficiency Particulate Air.” Basically, HEPA is a type of filter that traps a large amount (99.97%) of very small particles— as small as 0.3 microns. For size comparison, the period at the end of this sentence is about 400 microns in size! The size of pollens (30 microns), dust mites (20 microns), animal dander (1-20 microns) can be captured, but only if the air in the room is passed through the filter. HEPA air cleaners are believed to be the most effective, especially when compared to electrostatic or paper filters. Most vacuum cleaners would simply recirculate these very small particles back into the air of your home.

Q: Where can I find one?

A: There are many good options including Blueair® at, Hunter PermaLife™ at, and MinusA2™ at .

Q: How much do they cost?

A: HEPA air cleaners have a wide price range, primarily depending on features such as Clean Air Delivery Rate (CADR), which is the amount of particle-free air being delivered into the room. The higher the CADR, the larger the size room that can be cleaned of airborne particles. Other features that some HEPA air cleaners have are casters and digital remotes—nice, but not necessary. The number of air changes per hour is also important. The more air changes, the more particles removed from the air. Remember that most air cleaners are advertised at the highest air speed. With high air speed, the fan generates more noise. Eight or more air changes per hour may decrease airborne levels by 90% or more. This factor is most important for the allergic patient. So, back to price—they range anywhere from $350 to $900 (not including replacement filters).

Q: Do they work?

A: Yes, but air cleaners alone without using other measures to decrease airborne allergens and irritants may only be partially effective in improving symptoms of the patient with allergies or asthma. Some air cleaners are certified by the Allergy and Asthma Foundation of America (AAFA) in partnership with Allergy Standards Limited (ALS), which is “an independent program created to scientifically test and identify consumer products that are more suitable for people with asthma and allergies. The Certification Program has included certifying air purifiers in order to address some of the contaminants that may be present in indoor air and to scientifically validate that air cleaners contribute to the goal of allergen reduction.” It is best to avoid air cleaners that generate ozone, as this gas can exacerbate asthma. No air cleaner can eliminate all hazardous contaminants of second hand tobacco smoke.

So get out there and breathe that clean indoor air!