Why make the Paralda a HEPA model as opposed to an electrostatic model?
HEPA is recognized by industry experts as the best technology for filtering the air, especially the smaller sized particles that be breathed into your lungs. According to the American Lung Association "The overall effectiveness of an air cleaning device depends on the efficiency of the unit and on the amount of air drawn through it." HEPA filters are the most efficient mechanical filters for removing small particles which can be breathed deep into the lungs.1
Another consideration is that the electrostatic models can produce elevated levels of ozone - which is a harmful indoor air pollutant. Since Alen Corporation is introducing a product that is designed to improve the indoor air quality, the last thing we would want to do is to have it pollute the air. The California Air Resources Board will ban the sale of ozone air purifiers to residents in the state starting in 2009.2
A third reason is that with the electrostatic models, the user is required to clean the filter plates regularly. Besides the work involved in cleaning the plates, the user is in contact with the particles they are trying to get away from. If you have allergies, asthma or just don't want to have to deal with regular cleaning it's best to just swap in a new filter every 6-9 months.
1. "Air Cleaners" LungUSA Source: http://www.lungusa.org/site/c.dvLUK9O0E/b.4061173/apps/s/content.asp?ct=67087
2. "Evaluation of Ozone Emissions from Portable Indoor Air Cleaners" Air Resources Board Source: http://www.arb.ca.gov/research/indoor/esp_report.pdf
