Magic Ball's unique and effective operation principle ("Scrubbing Effect" + "Encapsulation" technology) ensures proactive and non-selective elimination of airborne bacteria/viruses and pollutants. Replacement of water and the Antibac 2K^® solution in Magic Ball regularly is beneficial as it ensures no storage of air contaminants and the continuous release of pleasant aroma from the purifier.

Common air purifiers in the market require the adoption of single or a combination of devices (e.g. HEPA filter, activated carbon filter, ozone generator, ionizer, ,UVC light generator, photocatalytic generator, plasma cluster generator, etc.) to achieve adequate air purification. These devices are often associated with drawbacks and possible hazards:

Overall

• Many air purifiers generate disturbing noise when used in maximum operation settings.  Quiet mode normally cannot provide adequate air purification.
• Common air purifiers impose higher electricity expense because of higher power consumption (around 50 - 70W).  The power consumption of Magic Ball is only 20W. 

Multiple Layers of Filters

• The filters trap germs or air pollutants in the air purifiers without eliminating them.  Moreover, if the air purifiers do not have built-in device to prevent backward airflow, it is possible for the trapped bacteria and air pollutants to be blown back into the air.
• Reusable filters create additional workload of regular cleaning to remove air contaminants trapped in the filters.
• For replacement-type filters, the performance of the air filters degenerate with time when pollutants build up in the filters.  Additional cost is also incurred for expensive filter replacement.
• Multiple layers of filters do not guarantee better effectiveness.  On the contrary, more filter stages mean higher air resistance and lower air delivery.
• Filers cannot remove toxic substances found in smoke such as carbon monoxide (Disclaimer stated in some air purifiers'catalogues.)

Activated Carbon Filter:

• Carbon filters cannot efficiently remove low molecular weight gases, e.g. formaldehyde, ammonia, etc. [1] 
• Most activated carbon filters use carbon fiber pads which are only impregnated with activated carbon dust, and are therefore not effective for the removal of gases/odors [1]

HEPA Filter:

• Designed for filtration of particles of 0.3 microns or larger, HEPA filter is not capable of removing air pollutants small than 0.3 microns. 
• Due to the damages/leakages made during mass production of filters, the actual efficiency of HEPA-based air purifiers is less than theoretical HEPA efficiency. [1]

Ozone Generator

• Ozone generator releases ozone which is unhealthy to human.  World leading health organizations warn against the use of ozone for air cleaning purposes: 
•  "When inhaled, ozone can cause lung damage.  A relatively low amount can cause chest pain, coughing, shortness of breath, and throat irritation.  Ozone may also worsen chronic respiratory diseases such as asthma and compromise the ability of the body to fight respiratory infections." [2] - US Environmental Protection Agency
•  "The Air Resources Board recommends ozone generators, air cleaners that intentionally produce ozone, not be used at home.  Ozone is a gas that can cause health problems, including respiratory tract irritation and breathing difficulty." [7] - Air Resources Board, State of California
•  "Independent studies have shown that ozone generators do not effectively destroy microbes, remove odor sources, or reduce indoor pollutants enough to provide any health benefits. [3] - California Department of Health Services

Ionizer

• Ions dispersed by ionizer attach to airborne particles, giving them charge so that the particles adhere to nearby surfaces and cause stains on walls and curtains.
• The pollutants are not actually removed and may become airborne again when they loose their charge over time.
• There are chances for the charged particles to be lodged in the human lung causing short- term and long-term health problems.
• Harmful ozone may be produced as a by-product.

UV Light Generator

• Some health organizations warn that UV light may not be a reliable way for sterilization:
•  "Relying on UV lamps germicidal effectiveness can lead to a false sense of security…..Even though a UV lamp maintains a blue-violet visible glow, this does not necessarily mean it still has a germicidal effect.  Also, the UV lamp needs to be cleaned periodically to remove dust and debris.  Note that UV lamps attract dust.  The dust and debris on a lamp will reduce the transmission of germicidal effect." [4] - Yale University, Office of Environmental Health and Safety
• UV light inhibits the growth of germs by changing their DNA, It does not kill them.
• UVC light generators may create hidden risk of the leakage of hazardous UV radiation.
• Additional costs are involved for the maintenance and replacement of bulbs:
•  "Bulbs still in use will be removed and disposed as they fail over the next two years. Actually they effectively fail in 6 months, but appear to still be working (no visual indication of failure)." [5] - University of Michigan, Occupational Safety & Environmental Health Department
• UV light imposes higher electricity expenses due to more energy consumption.

Photocatalytic Oxidation (PCO)

• PCO type air purifiers will generate hydroxyl radicals (OH) to decompose air pollutants.  However, hydroxyl radicals are highly reactive with cellular structures of living organisms and are very dangerous compounds. [6]
• The UV light of the PCO system may create hidden risk of the leakage of hazardous UV radiation.
• Additional costs are involved for the maintenance and replacement of bulbs:
• Higher electricity expenses are involved due to more energy consumption.

Plasmacluster Ions

• Plasmacluster ions dispersed by the air purifier will extract hydrogen from air pollutants to form hydroxyl radicals (OH) which in turn destroy pollutants'protein layer and transform protein into water.  As hydroxyl radicals are very reactive with cellular structure of living organisms, this may lead to health-risk concern.[6]
• Plasmacluster ions cannot remove toxic substances found in smoke such as carbon monoxide. (Disclaimer stated in some air purifiers'catalogues.)
• Higher electricity expenses are involved due to more energy consumption.

Nanoe Ions Generators

• Nanoe ions inhibit the airborne particles by surrounding them. They do not remove them.
• Nanoe ions are highly reactive and consequently last for a short period.
• Nanoe ions cannot be generated under certain temperature and humidity.
• Some hissing sound will be generated. (Extracted from the product catalogue of an air purifier.)
• Harmful ozone may be produced as a by-product.

References
[1] Indoor Environment Connections, Volume 1, Issue 12, October 2000. The Seven Sins Of Air Purifier Manufacturers.
[2] Environmental Protection Agency, United State. Ozone Generators that are Sold as Air Cleaners. http://www.epa.gov/iaq/pubs/ozonegen.html, updated April 14, 2007.
[3] Department of Health Services, State of California. IAQ Fact Sheet: Health Hazards of Ozone-generating Air Cleaning Devices. http://www.cal-iaq.org/o3_fact.htm, updated: January 1998
[4] Yale University, Office of Environmental Health and Safety. Clean Air Device (Primary Containment Device) Program Guide, July 2001. http://www/yale/edu/oehs/PDF files/cad 07 01.pdf.
[5] University of Michigan, Occupational Safety & Environmental Health. UVC Germicidal lights, May 30, 2002. www.umich.edu/~oseh/UVbulb.pdf.
[6] Hydroxyl - Wikipedia, the free encyclopedia, http://en.wikipedia.org/wiki/Hydroxyl_radical
[7] Air Resources Board, State of California. Hazardous Ozone - Generating "Air Purifiers". http://www.arb.ca.gov/research/indoor/ozone.htm, updated January 12, 2007.