Conducting the Audit: Evidence, Interviewing, Sampling and Findings
Sequence of an audit
Opening meeting (purpose, scope, criteria, method, confidentiality, safety, escalation route, no-surprises rule) → information collection → evaluation against criteria → findings → closing meeting → report. Communication during the audit is continuous; a serious risk (imminent danger, unpermitted emission) must be reported immediately and does not wait for the closing meeting.
Evidence that survives scrutiny
Acceptable sources are interviews, observation of activities and conditions, documents and records, data and performance indicators, and reports from external parties. Evidence must be verifiable and traceable - a finding that cannot be re-demonstrated from notes, documents or observation is hearsay. Triangulate: a claim made in interview should be confirmed by a record and, where possible, by observation.
Interviewing
Open questions (“walk me through how a waste transfer is approved”) beat closed or leading questions. Avoid asking an operator to explain a procedure they have never seen; ask what they actually do, then compare against the procedure. Silence is a tool - let people finish. Never interview with a notepad dictating their answers verbatim, and never audit an individual's personality rather than the process.
Sampling
Sample size and selection should be risk-based and representative: shifts, sites, seasons, high-impact processes, past incidents, contractors. A sample that is convenient but unrepresentative supports only a weak conclusion, and the report should state what was sampled.
Generating findings
Findings may be conformity, nonconformity or opportunity for improvement. Write them against a specific requirement, with objective evidence, so the auditee can act.
Worked example: a checklist says “check waste”. The auditor follows the trail: hazardous waste store → consignment notes → contractor's permit → annual return figures. The volume returned does not reconcile with the quantities purchased. The finding is the reconciliation failure against clause 9.1, not the checklist tick.