Our Cleanroom, class ISO 8 is a production department controlled atmosphere. The operation of a Clean Room is based essentially on the principle of forced circulation of super-filtered air in a sealed room that controls pollution microparticles.
Cleanroom classification is based on the count of microparticles from 0.5 microns in a defined volume of air. This classification or "certification" is issued by the maker once put into operation the room through a particle counter.
The less particles are counted, the more "clean" is the white room and the lesser is the class of belonging.
By comparison, in a normal office we will count few million particles of 0.5 microns.
In a public space, there are even 4-5 million particles. In a steel production we could measure almost 10 million