by David Parker
In the world of room air purifiers, there are a few inescapable parameters that determine which product is the right one for a particular consumer. These are the “facts of life” when it comes to air purification, and represent the trade-offs all consumers face when buying a unit.1
- Filtration type means the system used to extract particles from the air. Three main types are available – particle filters and ionizing filters. All air purifiers will use some kind of particle filtration and some add ionic to the mix.2
- Air flow is calculated at cubic feet per minute and represents the amount of air a unit will purify. It is tested with a new filter and degrades as a filter starts to get clogged.
- Style/brand is important because these units are a part of the “look” of a home. Units will be a visible part of the living space and décor.
- Features refers to all the incidentals that manufacturers add to make their product more attractive to consumers. These value-added items include things like timers, remote control, scenting the air and just about anything else they can think of.
- Energy used is based on how large the fan motor is and how much work has to be done to pull/push air through the unit.3
- Price/warranty considers both the initial purchase price and how much it costs to replace filters.
- Noise produced reflects both the quality of construction as well as design factors.
The main trade-offs are between price and the ability to quickly and quietly clean the air. Brand names and style also increase prices. Better filters cost more and moving more air through the filter also raises the energy costs to run a unit. Energy costs are usually not the main criteria, since, compared to other household appliances, an air purifier draws considerably less energy. In essence, it is similar to running a fan.
The way to make a good selection is to start with what you wish to accomplish. How large is the area you wish to cover? What is an acceptable purification level – is the unit meant to reduce asthma attacks, clean allergens from the air, reduce smells from mold/mildew, or lower the level of volatile chemicals in the house?4
Understanding what needs to be accomplished will guide the selection. A lower price for a unit that doesn’t do the job you want is a false savings.
Two abbreviations you need to know when shopping
The MERV, Minimum Efficiency Reporting Value, is a rating determined by spraying an aerosol into the air and then measuring what comes out on the “clean” side of the air purifier. The particles sprayed range in size and how many are removed (and what size) is used to determine how well the unit functions. Ratings are from 1 to 16 (higher number is better). According to the EPA, “Medium efficiency filters with a MERV of 5 to 13 are reasonably efficient at removing small to large airborne particles.”5
Not all manufacturers will list the MERV and this figure is most useful in whole home systems and HVAC installations.
The CADR, Clean Air Delivery Rate, is tested this way:6
The portable air purifier is placed in a testing chamber and the amount of contaminants measured before and after running the unit. This is compared with how quickly the same contaminants would “fall out” of the air and scored for different types of contaminants. The actual number reflects how much clean air would have to have been put in the room to obtain the same results.
According to the EPA, “if an air cleaner has a CADR of 250 for dust particles, it may reduce dust particle levels to the same concentration as would be achieved by adding 250 cubic feet of clean air each minute.”
Top PicksWhirlpool AP51030K Whispure with HEPA Filter can be found at several major retailers (Walmart, Best Buy, Sears) at $300 retail.6 Used to purify up to 500 square feet(total volume filtered 4.8 times per hour), with removal of 99+ percent of particles down to 0.3 microns. HEPA filter, activated charcoal pre-filter. Rated very quiet by users with 4 fan speeds. CADR rated 315 (higher for larger particles), 5-year limited warranty, in-store warranty available.
Downsides: Isn’t as stylish as other models. The large front size allows for greater airflow, but also needs larger (more expensive) filters. This raises the estimated yearly cost to run the unit at $208 (per consumer reports).
More info and specs on the Whirlpool AP51030K here via amazon.
Hunter 30547 features a cleanable HEPA filter coupled with an ionizer for odor removal. Purifies up to 496 square feet with a CADR of 330 and up to 6 air exchanges per hour. 7 Because the filter is cleanable, cost per year is somewhat less at an estimated $193.
Retails $250 to $300. 5-year limited warranty.8 This unit ranked very highly with Consumer Reports and availability may be limited due to demand.
Fellowes Quiet Air Purifier AP-300PH is rated for a smaller area (300 square feet), but is also less expensive at about $175. It is a “true HEPA” filter system and is extremely quiet as well as stylish, with the front grate (intake) hidden.9
For a single-room, sleeping application for allergy and asthma sufferers, this unit scores high because of a multi-stage filtration system that uses several technologies to remove different types of allergens:
The AP-300PH Air Purifier uses an innovative 4-stage system to safely remove airborne pollutants as small as 0.3 microns from your air. Thanks to True HEPA and carbon filters, Sanitized technology, and PlasmaTrue technology, the AP-300PH is able to remove viruses, allergens, germs, pollen, odors, dander, and much more from your air.
More info via amazon on the Fellowes AP-300PH here.
Honeywell 50150 is an odd-looking unit with intakes in a 360 degree pattern on a squat, barrel-shaped frame. This large surface area allows it to draw in more air with a smaller, less expensive fan. Price is good, at less than $125, but it only covers up to 235 square feet. The filter is a “true HEPA” but the CADR rating is rather low, at 150 (for cigarette smoke).10
More info and specs on the Honeywell 50150 here.
Other brand names worth checking out are: Oreck, GE, Blueair and Sanyo. All have excellent products although prices may drift higher than those mentioned in this article.