We had two HEPA filters replaced in a Grade C corridor outside our Grade B/A aseptic core, and QA is pushing for full EM requalification plus an extra media fill before restart; my read of risk-based GMP is that targeted requal (airflow/particles/smoke studies with 2 weeks of heightened EM) should cover it. Has anyone got inspection-tested SOP language or justification they can share, and what action/alert limits did you set for Grade C during the intensified monitoring?
We did this last year in a Grade C corridor and treated it as a ‘localized change’ per Annex 1: targeted airflow/particles and focused smoke at door interfaces plus pressure-recovery checks, then 2 weeks of heightened EM — no extra media fill since B/A wasn’t opened. Tip: capture pre/post cascade data and a short resuspension risk assessment; that satisfied QA and our inspector. Caveat: if balancing touched Grade B or downtime was long, add a line-clearance media fill — otherwise it’s a fire hose for a candle.