Buying Guide to Air Purifiers

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Breathe easy; choosing the right air purifier for your home or office just got a whole lot simpler. Designed to help reduce airborne particulates such as pollen, smoke, pet dander, dust and mold spores and aid in scoring a better night's sleep, the guide to finding the perfect air purifier is right under your nose.

Air Purifiers

What should you consider first in selecting an air purifier?

To begin, the terms air purifier or air cleaner mean the same thing. Familiarize yourself with the following 6 factors when purchasing a freestanding single room unit or a freestanding, whole-house machine to help you select the unit that best fits your needs.

  • Type of removal technology
  • Type of filter
  • Air change/Efficiency rate (ACH)
  • Clean Air Delivery Rate (CADR)
  • Room size

What do you really need to know about these 6 factors?

Type of removal/air cleaning technology
There are four primary types of air cleaning technology to choose from:
  • a. mechanical filtering,
  • b. electrostatic air cleaners,
  • c. ion generators
  • d. hybrid systems

The goal of each system is primarily the same: clean the air by reducing particles caused by pollution, interior fumes, smoking, dust, pollens, allergens and air borne irritants.

Type of filter
One of the biggest differences between the purifiers is the type of filter that is used. You will want to be aware of the three types.

HEPA (High Efficiency Particulate Air):
This filter removes high amounts of dust, as well as animal dander, pollen and dust mites. True HEPA is certified 99.97% efficient, so look for a model with True HEPA certification. It is important to note that most HEPA filters must be changed annually. Be sure to check on the cost of replacement, or choose a model that can be cleaned and reused.

ULPA (Ultra Low Penetration Air, or Ultra HEPA Filter):
This filter removes 99.97% of dust, pollen, mold, bacteria and airborne particles and is best for removing even the smallest particulates.

Charcoal or carbon filters work to remove larger particles such as those from smoke and odors. These types of filters are often featured as a pre-filter combined with HEPA or ULPA.

Air change/Efficiency rate (ACH)
The ACH rate, or Air Change per Hour, indicates how many times the air purifier will clean the room's air during the course of one hour. For example, 2 ACH means the air will be cleaned every 30 minutes, while 4 ACH means it will be cleaned every 15 minutes. The highest ACH rate is 6; or six complete cleanses per hour.
Clean Air Delivery Rate (CADR)
Now, while the ACH measures how frequently the air will be cleaned, the CADR, or Clean Air Delivery Rate, indicates the volume and speed at which particles will be filtered. Consider purchasing a purifier with a CADR rating that is at least equal to two-thirds of the room size (i.e., a 120 square foot room would require a cleaner with a minimum of 80 CADR rating).
Room Size
While CADR gives you a good rating to work with, it is often advisable to select a model that is meant to work in an area slightly larger than the actual room size you will be placing the air purifier in.

What does an air purifier sound like?

Since experts agree the most efficient air purifiers use motorized fans to pull in air, there is often ambient noise that accompanies this function. Sound levels vary according to maker and model. As noted previously, it may be helpful to purchase a more powerful machine than the room requires and run it at a lower speed for reduced sound. Air purifiers that do not use motorized fans will be the quietest, if not completely silent. On the flip side, some consumers report they appreciate a little ambient noise while sleeping. In this area, personal preference must prevail.

How can you limit the impact on your electric bill?

Since air purifiers run on electricity look for the ENERGY STAR certification. Energy Star certified room air purifiers are more energy-efficient.

How long should you run an air purifier?

For best results, air purifiers should be run continuously. In addition to creating cleaner air, continuously running an air purifier will have the added bonus of resulting in less household surface dust. It does not mean you'll be freed from chores completely, however, and it will still be necessary to vacuum and dust as needed. When cleaning day finally does roll around, be sure to run your air purifier at its highest setting until you finish since the activity of dusting and vacuuming stirs up particulates in the air.

How to care for your air purifier?

Keeping the air purifier clean and running smoothly is also important. Most models feature service lights that signal when filters need to be changed. Some indicator lights will go on when the filters are dirty and full of particles, others, however will light up automatically after running for a manufacturer-designated period of time.

Whether the unit features an indicator light or not, you should remove and clean the collector plate in an electronic precipitator air cleaner on a monthly basis. This can be done by washing the plate in a tub or sink or in some cases putting it in the dishwasher. Be sure to read the instructions that come with your machine.

HEPA filters should be changed on an annual basis.
At best, clogged filters or collector plates decrease the efficiency of air purifiers and at worst they can damage the machine, which makes regular cleaning of the filter or plate essential.