This is how a very efficient, silent air cleaner works > The filter makes the difference Down to the smallest particles How quiet is a whisper? Models and features
	Oxygen Air Cleaner has an electro statically charged filter that lets the air through without making a noise, whilst effectively trapping all particles. Since the air resistance is low, the fan needs only to turn slowly for a large quantity of air to be pumped through the filter. This also explains how it can be so efficient without using more power than a 20-watt light bulb. In other air cleaners, such as those equipped with HEPA filter, the air is pressed through the tightly woven filter, using a lot of energy and generating a lot of noise. As particles collect in a HEPA filter, the air resistance increases, which means that the quantity of air that is cleaned decreases over time.