Auditing a factory's cleanroom standards is a critical process to ensure product quality, safety, and regulatory compliance. Here’s a structured approach based on industry standards (ISO 14644, GMP Annex 1, FDA/EMA guidelines):

1. Define Scope & Objectives

   • Identify cleanroom classes (e.g., ISO 5, ISO 7), critical processes, and products affected.
   • Align with regulatory requirements (e.g., FDA 21 CFR Part 820, EU GMP Annex 1).

2. Review Documentation

   • SOPs: Gowning, monitoring, maintenance, disinfection, and environmental monitoring (EM) plans.
   • Validation Reports: Initial qualification, requalification, and ongoing monitoring data.
   • Training Records: Personnel certifications for cleanroom protocols.
   • Maintenance Logs: HVAC system, filters, and equipment servicing.

3. Audit Team & Tools

   • Assign auditors with cleanroom expertise.
   • Prepare tools: Particle counter, pressure gauges, swabs, UV light, camera, and non-shedding PPE.

Phase 2: On-Site Audit Execution

A. Facility Design & Infrastructure

• Airflow Patterns:
  • Verify laminar flow (HEPA-filtered air) with smoke tests or particle tracers.
  • Check air changes per hour (e.g., ISO 5: 300–600 ACH).
• Pressure Differentials:

  Measure positive pressure between adjacent rooms (e.g., ISO 5 > ISO 7 > ISO 8).

• Wall/Floor/Seals:

  Inspect for cracks, gaps, or peeling paint.

• Utilities:

  Validate HEPA filter integrity (DOP/PAO testing) and HVAC performance.

B. Personnel Practices

• Gowning:
  • Observe compliance with gowning sequences (e.g., boot covers → mask → gloves).
  • Check for skin exposure, jewelry, or improper fit.
• Training:

  Interview staff on EM procedures, contamination control, and emergency actions.

• Behavior:

  Monitor for unnecessary movements, talking, or non-compliant activities.

C. Operational Controls

• Material Transfer:

  Verify pass-through autoclaves or airlocks for decontamination.

• Cleaning & Disinfection:
  • Review logs and inspect surfaces for residue (e.g., ATP testing).
  • Check compatibility of disinfectants with surfaces.
• Equipment & Tools:

  Ensure smooth surfaces, no rust, and proper cleaning protocols.

• Waste Handling:

  Confirm segregated, sealed waste containers.

D. Environmental Monitoring (EM)

• Particle Counts:

  Compare real-time data to ISO 14644 limits (e.g., ISO 5: ≤3,520 particles/m³ ≥0.5μm).

• Microbial Monitoring:
  • Review settle plates, surface swabs, and air sampler data.
  • Investigate excursions (e.g., high counts post-maintenance).
• EM Frequency:

  Validate against risk-based schedules (e.g., daily ISO 5, weekly ISO 7).

E. Change Control & Deviations

• Assess CAPAs for past deviations (e.g., filter failure, contamination events).
• Verify documentation for process/equipment changes.

Phase 3: Post-Audit Reporting & Follow-Up

1. Document Findings

   • Use non-conformance reports (NCRs) with evidence (photos, data, timestamps).
   • Cite specific standards (e.g., "Violation: ISO 14644-1, Section 6.3").

2. Prioritize Risks

   Classify issues as Critical (product safety), Major (compliance), or Minor (procedural).

3. Action Plan

   Assign responsibilities, timelines, and verification steps for corrective actions.

4. Re-audit

   Verify closure of NCRs during follow-up audits.

Key Standards & Regulations

Common Pitfalls to Avoid

• ❌ Skipping unclassified areas (e.g., gowning rooms).
• ❌ Ignoring supplier audits for materials entering the cleanroom.
• ❌ Over-reliance on historical data without real-time checks.
• ❌ Neglecting training refreshers for seasonal/temp staff.

Quick Reference Table: Critical Checks

By following this structured approach, auditors can systematically identify gaps, ensure continuous compliance, and mitigate contamination risks. Always tailor the audit to the cleanroom’s class and industry-specific requirements.