AIOH Compliance Decision Framework

AIOH occupational hygiene exposure compliance decision framework based on the AIOH Compliance Decision Guide. Typically routed to by the request-router skill when occupational hygiene monitoring data is detected, or invoked directly by name (e.g. "run AIOH compliance analysis", "assess this SEG using aioh-compliance"). Use this skill for occupational exposure compliance assessment, AIOH compliance categories, UCL 95% compliance testing, U-parameter group compliance test, MVUE calculation, Land's exact method, exposure data treatment, lognormal distribution fitting, SEG compliance decisions, occupational hygiene statistics, exceedance fraction calculation, when to use UCL vs U-test, method disagreement guidance, or any question about interpreting occupational exposure monitoring data for compliance purposes. Also trigger when reviewing or generating occupational hygiene reports that reference AIOH methodology, workplace exposure standards, or statistical analysis of airborne contaminant data.

Key Statistical Parameters

Compliance Categories (AIOH Framework)

The AIOH framework classifies exposure profiles into five categories based on the primary metric (UCL₉₅% of MVUE is recommended):

• Category 0 (Ideal): Metric < 0.1 × OEL — Exposure well controlled, minimal monitoring needed
• Category 1 (Good): Metric < 0.5 × OEL AND P95 < OEL AND Exceedance < 5% — Routine monitoring appropriate
• Category 2 (Acceptable): Metric < OEL AND does not meet Category 1 — Increased monitoring frequency recommended
• Category 3 (Unacceptable): Metric ≥ OEL OR Exceedance ≥ 5% OR P95 > OEL — Controls required
• Category 4 (Critical): Metric > OEL AND observed exceedances > 10% — Immediate action required

Two Compliance Testing Methods

Two statistical methods are available for group compliance assessment. Each answers a different question at a different confidence level. Read references/method-guidance.md for detailed guidance on when to use each method and how to handle disagreements.

UCL₉₅% of MVUE (Land's Exact Method) — the primary Australian method:

• Calculates the 95% upper confidence limit of the arithmetic mean using Land's exact method
• If UCL₉₅% < OEL, the SEG is considered compliant at 95% confidence
• Recommended by AIOH Section 13.6 as the primary compliance metric
• Used by many large Australian organisations

U-Parameter Group Compliance Test (INRS / NF EN 689) — supplementary European method:

• Calculates U = (ln ES − ln GM) / ln GSD
• Compares against Table 13.1 limiting values at 70% confidence
• Tests whether fewer than 5% of exposures exceed the ES
• Requires minimum 6 measurements
• The 70% confidence level provides a balance against false positives and false negatives

Method Selection Guidance (Summary)

When Methods Disagree

When the UCL₉₅% and U-parameter test give different compliance verdicts, this is a borderline situation. The guidance is:

1. UCL₉₅% takes precedence in Australian practice — it is the more conservative primary metric
2. Collect more data — the disagreement typically indicates the exposure profile is near the compliance threshold
3. Examine SEG homogeneity — consider whether the SEG should be subdivided
4. Report both results — the U-test provides useful context about how close the profile is to compliance

For full details on disagreement scenarios, read references/method-guidance.md.

Australian English and Reporting Conventions

• Use Australian English spelling throughout (analyse, minimise, behaviour, labour)
• Use conservative, neutral language — describe findings factually without emotive terms
• Reference the Workplace Exposure Standard (WES) or Occupational Exposure Limit (OEL) as applicable
• Cite the AIOH Compliance Decision Guide and relevant sections when providing methodology rationale
• All legislative references should cite the applicable jurisdiction (e.g., WHS Regulation 2011 (Qld))

References

• AIOH (Australian Institute of Occupational Hygienists). Compliance Decision Guide. (Primary reference)
• NF EN 689:2018. Workplace exposure — Measurement of exposure by inhalation to chemical agents — Strategy for testing compliance with occupational exposure limit values
• Land, C.E. (1971). Confidence intervals for linear functions of the normal mean and variance. Annals of Mathematical Statistics, 42(4), 1187–1205
• Leidel, N.A., Busch, K.A. & Lynch, J.R. (1977). Occupational Exposure Sampling Strategy Manual. NIOSH Publication No. 77-173
• Shapiro, S.S. & Wilk, M.B. (1965). An analysis of variance test for normality. Biometrika, 52(3–4), 591–611