A dust particle visible to the human eye has a size of 500 micrometres = 0.5 mm. A fine dust particle that is no longer visible to us is smaller than 10 micrometres = 0.01mm. And the finer these particles are, the easier and deeper they can be absorbed via the respiratory tract into the bloodstream and thus into the... organs. It is also called overcoming the blood-air barrier. This makes the new printer filter CLEAN OFFICE PRO, which is more powerful than all printer filters sold so far, all the more important.