All of air purifiers used in many households and offices have
built-in filters to keep the indoor air clean all the time. These
filters composed of filter media enabling to filter out fine
particles, dust and bacteria from the air. By utilizing filter
media which is called hepa-filter or ultra-filter, it removes not
only fine dust but also 0.3 micron of particles, as well as more
stable filtration efficiency. However, it has an unavoidable part
that customers must bear the additional cost of filters because of
the cycle of its frequent replacement than that of existing ones.
