Clean Room classification
There are certain environments where it is necessary to limit the quantity of airborne particles. This applies, for example, in the pharmaceutical, electronics and food industries and in certain hospital environments.
The international EN ISO 14644-1 standard (classes 1 to 9) is used for the classification of air cleanliness. This is the official standard, but the US Federal standard 209E (classes 1 to 100 000) is also widely spread. The pharmaceutical industry is regulated by Good Manufacturing Practice (GMP) standards (class A to D).