Fresh air & Re-circulation air % in HVAC

Dear All,
In our mind today one question have raised i.e.
What should be the % of fresh air as well as re-circulated in HVAC system for Pharmaceutical parental plant.
Where this is mentioned please give references.

HVAC market is subject to high end innovations. In recirculation mode, HVAC systems monitor several cabin air parameters, recycle the air through the air conditioning unit back into the cabin and limit the fresh air inlet to the minimum, while satisfying the parameters set by particulars.

NYC Commercial HVAC Services

Hi David. My company just undergone an inspection and one of the findings was that 'The percentage recirculated vs fresh air was not provided in the qualification of the HVAC. Is there any test conducted for such and how does one go about executing the test. Please advise

Kindly regards