I would assume these bearings are required to meet specific "bearing industry standards"... and as such I would assume those standards cover or direct you to applicable cleanroom standards that must be met.
Like maybe your bearings must apply to some ASTM standard and that implies that miniature and instrument precision bearings for example require cleanrooms per ISO 14644-1 and -2,etc..
Then those standards will specific the micron filtration/laminar flow,etc.. for the standard required specific cleanroom classification. Class 10,000,etc...
http://en.wikipedia.org/wiki/Cleanroom

As far as the industry standards most are met that i can tell, but there is a smoke and mirrors charade that takes place at my work. So it's hard for me to get all the facts. I was under the impression since we are A/S iso9001 certified there would be a set of standards for specific applications. Such as "none flight critical bearings" ABEC 5. My boss says its according to the customer, but It's hard for me to believe that is all the information. I will look into it more using ASTM and ABMA. Thank you again for your time in this matter.