HEPA filtration in Coating process

Does anybody know the main reason for HEPA filtration (as final filters) of inlet air (HVAC unit) in Tablet Coating machines? What is the minimum filter efficiency for inlet air in coating process ? Does it depends of OEL level ?
Please advice and post reference if any ?

Thanks !

Dear,

The inlet hot air directly contacts with the product, so the air has to be filtered through the HEPA filters(0.3 micron filters) and its meeting with ISO 8 Classification. Filter efficiency shall meet the ISO-8 requirements for tablets coating process.

Thank you prasadraokili,

please post reference for “ISO-8 requirements for tablets coating process” as you mentioned.