Iso 14644-3.pdf - //free\\

The 2019 edition is strict. Your test equipment (flow hoods, particle counters) must have a known calibration uncertainty. A reported velocity of 0.45 m/s might actually be 0.42 m/s when you account for the instrument's ±7% error. This must be declared.

To verify that environmental parameters (such as airflow, pressure, and containment) are functioning effectively to protect sensitive processes. Iso 14644-3.pdf