What is a HEPA filter made with?
The filtering material or media is made of very thin glass fibres. The glass fibres are made into paper, much the same way as cellulose or wood fibres are used to make paper. In thickness and texture, the HEPA media is similar to blotting paper. Air cannot easily get through the dense paper, so a very large area of paper must be used to permit filtering of a significant volume of air. To get a large area of the media into the filter, it is pleated, creating an “extended surface”. For example, an enviracaire True HEPA filter measuring 60 cm can contain as much as 12 square metres of filter media for maximum cleaning efficiency.
