1. Filter Efficiency top

Clean Air Delivery Rate (CADR), is an important criteria to consider in selecting an air purifier. CADR is a measure of total volume of air that an air purification system cleanses of a specific pollutant in one hour. Test results are expressed in cubic feet per minute (cfm), for three "yardstick" particles: tobacco smoke, dust and pollen.

The higher the test numbers, the better the unit's overall ability to clean indoor air.

Next, filter efficiency differs for particles of different sizes. Look for the percentage of particles removed, and the smallest particle size captured. BlueAir's HEPASilent™ filter technology receives a 99.9% efficiency rating for particles 0.3 microns in size, and a 99.97% efficiency rating at 0.1 micron.

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2. Capacity top

Air volume capacity is the next most important element when selecting the best in-room air cleaner. Choose a unit that is rated to handle the total volume of air in the room where it will operate. This value is expressed as recommended room size.

Room size recommendations are expressed in square feet, assuming an 8-foot ceiling.

If your room has a ceiling higher than 8 feet, convert the recommended room size of an air purification unit to cubic feet by multiplying by 8 (the ceiling height AHAM assumes). Next, calculate the cubic footage of your room by multiplying length x width x height and compare.

3. Specific Health Concerns top

Air cleaning alone cannot adequately remove all of the pollutants typically found in indoor air. However, when combined with source removal and adequate ventilation, the EPA considers air cleaning a viable means of improving indoor air quality. With the exception of allergens and airborne pathogens, the size of a given particle determines the degree of potential threat to human health. Generally, airborne particles are identified by the EPA as small (0.1 to 0.3 micron), mid-range (0.3 to 0.9 micron) and large (1.0 micron or larger).

Large Particles (1.0 micron and larger)

Large particles include house dust and some of the larger pollen and bacteria.

Large particles are usually trapped by cilia in the nasal passages before reaching the lungs. Look for high efficiency for large particles when sinus conditions or immune disorders are present, and when asthma is triggered by pollen.

All HEPA filters capture particles of this size, while electrostatic filters generally do not.

Mid-Range Particles (0.3 to 0.9 micron)

Mid-range particles include house and textile dust, pollen, pet dander, dust mites and their feces, many bacteria, auto exhaust, mold spores, and particles from laser printers and copiers.

Particles of this size present the greatest health concern because they are small enough to get past the cilia in the nasal passages and too large to be easily exhaled. They are more likely to become lodged in lung tissue and are suspect in a wide range of health problems related to indoor air pollution, from headaches and dizziness to cardiovascular disease and cancer.

Look for an air filter with high efficiency for mid-range particles when respiratory conditions are present. HEPA filters generally capture mid-range particles.

Small Particles (0.1 to 0.3 micron)

Small particles include many viruses, bacteria, gases and chemical fumes.

Although these small particles are inhaled and exhaled more easily than mid-range particles, they may irritate already compromised breathing passages and lungs.

Look for high efficiency for small particles when respiratory conditions, immune disorders or cardiovascular disease are present, and when asthma is triggered by strong odors and fumes. The addition of active electrostatic filtration to HEPA filtration allows BlueAir units to achieve higher efficiency for small particles.

4. Legitimacy of Manufacturer Claims top

Buyers need not rely solely on a manufacturer's efficiency claims. Instead, consult the Association of Home Appliance Manufacturers (AHAM), an independent industry organization that publishes the results of their overall room air cleaner performance tests. AHAM's performance tests are recognized as accurate and impartial by the EPA and the American Lung Association. Ratings can be found online at www.cadr.org.

As with any appliance purchase, it is important to check the manufacturer's legitimacy and confirm performance claims before you buy. Common sense red flags might include uncorroborated filter efficiency and air volume capacity statements, unwillingness to submit an air cleaner for independent AHAM testing, no physical address on brochures or websites, lack of detailed information on filter composition or technology, or the promise of extremely long filter life when compared to similar units.

5. Indoor Environmental Factors top

It is important to consider which types of particles affect the patient's respiratory health and how environmental conditions might impact an in-room air cleaner's performance and maintenance requirements.

Dust:

Some units include a built-in BlueAir pre-filter, which can help strain out large dust particles before they fill the spaces between HEPA filter fibers. You can also trap dust by installing vent filters over central

heating and air conditioning registers.

 

Humidity:

Environments with high relative humidity levels (over 50%) are of concern when allergies or asthma are triggered by mold and mildew spores and when immune disorders are present.

 

Absorbent HEPA filter media retain ambient moisture and create an ideal internal environment for mold and bacterial growth. To combat this growth, some manufacturers recommend periodic filter sterilization or the addition of chemical based bacteriostats.

Hydrophobic filter media, such as the polypropylene employed in BlueAir's HEPASilent™ filter, counter mold and bacterial growth by eliminating moisture retention. Water-repellent fibers perform as well as absorbent fibers in the context of HEPA filtration, while remaining dry and free from water-related mold and bacteria colonization.

Tobacco Smoke: Tobacco smoke is one of the three "yardstick" pollutants in AHAM's CADR testing. When tobacco smoke is present in the indoor environment, refer to CADR test results for the units you are considering. The higher the CADR rating for tobacco smoke, the better the unit's ability to remove it.

Keep in mind: the EPA's Office of Air and Radiation (OAR) notes that while HEPA filters can remove some tobacco smoke particles, none remove all of the 4,000 chemicals that comprise tobacco smoke.

VOCs:

Volatile organic compounds (VOCs) are gas particles introduced into room air through the indoor use of pesticides, glues, solvents and cleaning agents. They include a staggering variety of chemicals emitted as gases from petroleum-based solids and liquids.

 

More often an industrial problem, VOCs are likely to be present in homes where graphic production, crafts involving glues and paints, photographic processing, and auto or other repairs involving solvents take place. VOC levels may rise during remodeling and redecorating, and following pest control or aggressive cleaning activities.

In environments where VOC sources may be present, look for a HEPA filter incorporating activated carbon compounds as a filter media. In its publication Residential Air Cleaners; Summary of Available Information, the EPA's Office of Air and Radiation (OAR) notes activated carbon compounds can effectively adsorb gaseous pollutants. However, filter replacement is critical to avoid the eventual release of VOCs from a saturated filter. The OAR recommends changing the filters as recommended by the maker to reduce the risk of outgassing.

6. Operating Cost top

Replacement filters are an ongoing expense for the life of the unit. Check the manufacturer's recommended replacement interval and the filter cost, as well as shipping charges.

The energy cost of 24 hour per day use should be considered during the selection process. Look for the unit's energy use, expressed as watts where dimensions and other technical specifications are listed.

7. Construction Quality top

As with any appliance, look for a system with quality construction, especially internal moving components such as fans and blowers. The durability of materials used for the cabinet is a strong secondary consideration. Because portable in-room units are subject to more handling than fixed systems, units with metal housings are more durable than plastic cabinets, and are likely to produce less operating noise.

In addition, the unit should be safety certified by with an organization such as Underwriters Laboratory (UL) or ETL. All of BlueAir's units are ETL certified.

8. Ease of Use top

It is important to take the user's physical abilities and dexterity into account, as filter change can be as simple as lifting the unit's lid and sliding filters in and out, or a complicated operation involving hand tools. Replacing a BlueAir filter requires no heavy lifting or tools.

Operating instructions should include detailed directions for filter replacement and periodic internal cleaning. Internal cleaning is a particular issue with electrostatic precipitators, in which filters are cleaned and sterilized rather than replaced.

9. Warranty top

As with any appliance, choose an established manufacturer with a comprehensive, long-term warranty. Government regulations require that warranties be made available at the point of purchase, even when purchases are made through the mail or online.

Consider both the length of the warranty and what it covers. Most in-room air cleaner manufacturers offer a limited warranty for a specific period of time. In the event of product failure, a limited warranty only covers the components specified, and may not cover the cost of diagnosis, labor, and/or shipping.

10. Bells and Whistles top

Operating noise can be a significant factor when using the unit 24 hours a day as recommended. Knowing this, a manufacturer may claim that their product is "virtually noiseless." Confirm vague claims by requesting specific operating noise values, expressed in decibels. On the lowest setting (the typical operating speed), Blue Air units are about as quiet as the average desktop computer - approximately 35 decibels.

The draft created by the unit's air processing system is not as easily quantifiable as noise or efficiency levels. Generally, a draft must be evaluated by seeing (or feeling) the unit in operation. Some in-room air cleaners direct a strong stream of air from one or two exit points. BlueAir diffuses air through many exit points to mitigate uncomfortable drafts.

While cabinet sizes vary, it is not accurate to assume that a large unit is more effective, or that a smaller unit is less effective. Your in-room air purifier selection should be based first on efficiency and air volume capacity. Then, use space requirements to narrow the choice between units of similar efficiency.

Most units require specific clearance from walls and windows in order to operate effectively. Look for a unit that physically fits within the environment in which the unit will be operating.