Occupational Hygiene Monitoring Plan (OHMP)
A Systematic Framework for Identifying, Assessing, and Controlling Workplace Health Hazards
An Occupational Hygiene Monitoring Plan is the foundational document that governs how a business identifies, measures, evaluates, and controls worker exposure to health hazards in the workplace. It is not a one-off report or a box-ticking exercise. An OHMP is a living, structured programme that translates the general duty of care under the Work Health and Safety Act 2011 into a practical, auditable system of exposure management. For any business where workers are exposed to airborne contaminants, noise, vibration, thermal stress, biological agents, or radiation, the OHMP is the document that ties together every other compliance activity — from baseline air monitoring to health surveillance, from engineering control verification to respiratory protective equipment programmes.
Why Every Australian Workplace Needs an OHMP
Australian WHS legislation does not prescribe the exact format of an occupational hygiene monitoring plan, but the legal obligations that make one necessary are explicit and enforceable. Under the WHS Regulation 2025, a person conducting a business or undertaking (PCBU) must ensure that atmospheric monitoring is carried out if there is uncertainty about whether the concentration of an airborne contaminant at the workplace exceeds the relevant exposure standard, or if monitoring is necessary to determine whether there is a risk to health. The regulation further requires that monitoring be carried out by a competent person using valid and suitable methods. These provisions make clear that monitoring cannot be random. A competent person — in practice, a qualified occupational hygienist — must determine a monitoring strategy. That strategy is the OHMP.
Core Components of an OHMP
Workplace Characterisation & Process Mapping
Thorough mapping of every process, task, and operation that generates a health hazard. Documents substances used or generated, physical state, duration and frequency of worker exposure, existing controls, and ventilation conditions. Determines the scope of the entire monitoring programme.
Similar Exposure Group (SEG) Identification
Groups workers with similar exposure profiles based on task, substance, duration, physical environment, engineering controls, and PPE use. SEG composition directly determines the number of monitoring samples required and the statistical validity of the exposure assessment.
Contaminant Identification & Prioritisation
Identifies every substance of concern and prioritises based on toxicity, severity of health effects, likelihood of exposure at levels approaching the WEL, and number of workers exposed. Accounts for mixed-exposure scenarios using the additive formula.
Monitoring Strategy & Sampling Design
Specifies monitoring type (personal, static, biological), sampling equipment and analytical methods, sampling duration, number of samples per SEG, and frequency of monitoring rounds. Defines the statistical approach to data analysis.
Trigger Levels & Action Criteria
Defines tiered action thresholds: below 10% WEL (reduced monitoring), 10-50% WEL (routine monitoring), above 50% WEL (enhanced monitoring and control review), approaching/exceeding WEL (immediate corrective action and health surveillance referral).
Health Surveillance Integration
Links monitoring data to health surveillance protocols. Specifies which surveillance is triggered by monitoring results, how data flows to the health surveillance provider, and how surveillance findings feed back into the monitoring strategy.
Documentation & 30-Year Record Retention
All monitoring data, sampling records, calibration certificates, analytical results, and interpretive reports documented and retained for 30 years under WHS Regulation 2025. Specifies documentation standards, format, and the process for making results available to workers.
OHMP and the December 2026 WEL Transition
The transition to Workplace Exposure Limits on 1 December 2026 represents the most significant change to Australian occupational exposure standards in decades. For businesses that already have an OHMP, the transition requires a formal review to update all referenced exposure limits, recalculate trigger levels against the new WEL values, reassess SEGs where tightened limits change the risk profile, and identify processes where existing controls may be insufficient. For businesses without an OHMP, the transition period is the strongest argument for developing one. Baseline monitoring before December 2026 provides the data needed to understand current exposure levels, identify gaps, and plan control upgrades.
The Cost of Not Having an OHMP
| Category | Corporate | Individual | Description |
|---|---|---|---|
| Category 3 | $748,492 | $149,698 | Failure to comply with a health and safety duty |
| Category 2 | $2,235,363 | $447,122 | Failure exposing a person to risk of death or serious injury |
| Category 1 | $11,150,183 + 10 years | $2,318,844 | Reckless conduct |
| Industrial Manslaughter | $20,000,000 | 25 years imprisonment | Gross negligence causing death |
Get Started with an OHMP
If your workplace involves airborne contaminants, noise, chemical handling, or any other health hazard, an OHMP is not optional. The December 2026 WEL transition makes this the right time to act.