Define the claim that a containment study must support before selecting a surrogate or positioning a sampler. A study may compare designs, verify equipment against a purchase specification, investigate an emission source or support an occupational exposure-control assessment. These purposes overlap, but they do not justify identical protocols or conclusions.
Containment performance is conditional on the tested equipment, material, tasks and environment. A report stating a low airborne concentration without those conditions is difficult to interpret. The study must make its intended conclusion, uncertainty and limits visible, especially when results will be used to approve a process involving a more hazardous active compound.
1. Understand what SMEPAC guidance provides
[GUIDANCE] The current public ISPE description identifies the third edition, published in December 2024, as SMEPAC: Standardized Methodology for the Evaluation of Pharmaceutical Airborne Particle Emissions from Containment Systems. It provides a recognized framework for evaluating airborne particle emissions from containment systems within its scope.
Use the applicable licensed guidance and competent expertise when developing a protocol. This article does not reproduce proprietary protocols, sampling layouts or acceptance tables. It explains the engineering decisions that a project team needs to resolve and why a generic reference to SMEPAC is not a complete test specification.
Confirm which edition, procedures and adaptations the proposed study uses. A statement that equipment is SMEPAC tested should be followed by the actual report and its conditions. It is not a universal certification that the equipment is suitable for every compound, operation or occupational exposure limit.
2. Separate emissions from actual exposure
A surrogate study evaluates airborne emissions under specified conditions using a selected material. Actual worker exposure depends on the intended compound, work pattern, environment, controls and exposure routes. The surrogate evidence can inform the assessment, but a direct one-to-one equivalence should not be assumed.
Personal breathing-zone sampling characterizes air in the worker's breathing zone during the sampled period. Fixed-area sampling characterizes air at selected locations and can help investigate release patterns. Area results are not personal exposure measurements, even when the sampler is near the equipment or an operator.
Surface sampling can provide additional information about deposited material and contamination pathways. It answers a different question from airborne sampling. Similarly, enclosure leak testing, pressure measurements and filter integrity tests support understanding of specific functions but do not replace task-based emission evaluation.
3. Establish the acceptance basis before testing
Define the containment objective through the intended process, hazard assessment, occupational hygiene strategy and procurement requirements. State the metric, sampling context and interpretation rules. Avoid inserting a supplier's convenient target without checking whether it supports the site's decision.
An occupational exposure limit normally has a defined substance, reference period and interpretation. A short surrogate task result cannot be compared mechanically with a different substance's full-shift limit and presented as compliance. A competent hygienist must consider the relationship between task data, work pattern and relevant criteria.
Occupational exposure bands are also system-specific. An OEB label alone does not define a study acceptance concentration. Identify the banding scheme and translate its implications into a justified project requirement. Where toxicological information is incomplete, document the uncertainty and the conditions for proceeding.
4. Select and justify the surrogate
Assess properties that influence release and measurement: particle-size distribution, dustiness, flow, adhesion, moisture response and detectability. Consider whether the surrogate represents the task's challenges and whether its behaviour differs materially from the intended product. Similar appearance is not a sufficient rationale.
The surrogate must also be appropriate for the test environment and manageable under the study's safety controls. Review cleaning, background contamination and the possibility of interference with analysis. Record its identity, batch information and handling conditions to support interpretation and reproducibility.
Explain how differences from the intended process affect the conclusions. A more freely flowing material may not challenge a blockage-recovery task, while a more adhesive material may alter residual contamination at a connection. There is no universal surrogate that is automatically worst case for every operation and mechanism.
5. Define representative tasks and challenge conditions
Map the complete operating sequence, including preparation, loading, transfer, sampling, discharge, disconnection, cleaning and waste removal where within scope. Identify the tasks most likely to release material. A study limited to steady operation can miss the boundary transitions that dominate exposure potential.
Use quantities, packaging, equipment arrangement and operator actions that support the intended claim. Document operator training and the approved method. If the system's performance depends on a defined technique, that dependency belongs in the report and later procedures; it should not be hidden by describing the result as an intrinsic equipment property.
Select challenging conditions through a reasoned assessment. Include relevant equipment loading, repeated operations or other variability where appropriate. The number of runs, operators and repetitions must follow the study objective and guidance, not an invented universal rule. Unplanned unsafe conditions should not be created merely to make a test appear severe.
6. Build a sampling and analytical strategy
Choose sampling methods and locations according to the study questions and applicable methodology. Document flow settings, duration, calibration and handling of samples as required by the approved protocol. Confirm that the arrangement does not obstruct the task or change the containment behaviour being evaluated.
Evaluate analytical sensitivity before execution. The reporting limit must be sufficiently informative for the decision, considering the sampled air volume and calculation method. A result below quantification does not mean zero emission, and an insufficiently sensitive method cannot demonstrate compliance with a criterion below its meaningful reporting capability.
Include appropriate blanks, background assessment, sample identification, chain of custody and quality controls. Review potential contamination during preparation, transport and analysis. The analytical method should be suitable for the surrogate and matrix, with recovery and other relevant performance characteristics understood.
7. Record conditions that affect interpretation
Document the tested configuration in enough detail to relate it to the supplied equipment: model, interfaces, filters, control settings, software where relevant, packaging and connected systems. Capture relevant room and ventilation conditions. Photographs or diagrams can support clarity when they do not disclose confidential information unnecessarily.
Record actual task timing and departures from the planned sequence. Note interruptions, spills, difficult docking, liner problems and unusual operator movements. These observations can be essential to understanding a result and identifying the mechanism behind an emission.
Preserve individual results and raw records. Summary statistics can help, but they should not conceal a high result, an invalid sample or an unsuccessful task. Define the treatment of non-detects, missing samples and deviations before analysis wherever possible, and explain any justified changes transparently.
8. Use an interpretation matrix
| Observation | What it may support | What it does not establish alone |
|---|---|---|
| Low measured surrogate concentration | Good performance for the sampled tasks and conditions | Acceptable exposure for every intended active compound |
| Non-quantified sample | Result below the method's reporting capability | Zero release or automatic compliance |
| Elevated area sample | A possible local emission or contamination pathway | The operator's personal exposure concentration |
| Acceptable leak test | Integrity under the specified boundary test | Acceptable emissions during docking or cleaning |
| Normal enclosure pressure | A monitored operating condition was maintained | Absence of contaminated surfaces outside the enclosure |
| Variable repeated results | Performance depends on task or other conditions | That averaging alone resolves the variability |
Interpret the data with the observations and the study's predefined decision rules. An unexpected result may reflect a real release, sampling issue, background contamination or a combination. Investigate before assigning a cause, and avoid selecting only the explanation that preserves a preferred procurement outcome.
9. Handle failures and repeat testing properly
If a criterion is not met, identify the affected task and the plausible release mechanism. Review the physical boundary, sequence, airflow, packaging and operator interactions. Assess whether the study was valid and whether immediate restrictions are needed for related work.
Correct the underlying issue through design, procedure or another justified control. Define which tests need repetition and whether the change affects previously satisfactory tasks. A repeated result is useful when it evaluates a documented correction; simply repeating until a lower value appears does not establish reliable performance.
Keep original results and the full investigation in the report. State the final approved configuration and any operating restrictions. If acceptance depends on a specific container, liner, technique or extraction condition, ensure that purchasing, training and change control preserve that dependency.
10. Connect study evidence to occupational assessment
[OCCUPATIONAL HEALTH REQUIREMENT / GUIDANCE] A competent assessment of actual exposure considers the intended substance, work pattern, relevant routes and jurisdictional requirements. EN 689 addresses assessment of inhalation exposure to chemical agents for comparison with occupational exposure limit values within its scope; it is not interchangeable with an equipment surrogate-emission protocol.
Use the containment study to identify tasks, uncertainties and monitoring priorities. Consider differences between test personnel and routine users, factory and site conditions, clean and aged components, and single tasks versus a working shift. Additional workplace evidence may be needed before or during routine operation according to the approved strategy.
[QRM] Coordinate product cross-contamination assessment with the occupational workstream. An airborne performance result can be relevant context, but it does not replace cleaning validation or a health-based evaluation of carryover into another product. Keep the conclusions tied to the evidence actually collected.
11. Example: good steady-state results, weak undocking
A study of a powder charging system finds low results during material movement but a higher result associated with undocking. The team reviews the sequence and identifies residual material near the connection as a hypothesis. It checks observations, background and analytical controls before concluding that the interface is responsible.
The design or procedure is then revised to address the supported mechanism. The revised study covers undocking and any other tasks affected by the change, using the approved interpretation rules. The report retains the original results and explains the final configuration rather than presenting only the successful repetition.
This is a hypothetical example, not a published case. It demonstrates why task resolution matters: a single combined average might obscure an intervention that deserves a specific engineering correction and an occupational assessment.
12. Study-readiness checklist
- State the intended claim and the decisions the study will support.
- Define acceptance criteria and interpretation rules before collecting data.
- Justify the surrogate and explain differences from the intended material.
- Include representative boundary transitions and relevant non-routine tasks.
- Distinguish personal, area and surface sampling objectives.
- Verify analytical capability, blanks, background and sample handling.
- Record the configuration, operator method and actual task conditions.
- Retain individual results, deviations and the rationale for any exclusions.
- Investigate failures and link repeat testing to documented corrections.
- Connect the conclusions to the actual exposure-control strategy and lifecycle controls.
[GUIDEGXP RECOMMENDATION] Accept a performance report only when a technically competent reviewer can reconstruct what was tested and why the conclusion follows. A concise summary is useful for decisions, but it should remain traceable to the protocol, observations, analytical evidence and limitations. This is the difference between a defensible containment claim and an attractive number detached from the process.
Sources, scope and engineering recommendations
Source status checked on 25 September 2026. Apply each document within its jurisdiction and scope. GEP and GuideGxP recommendations are engineering advice, supported by risk assessment; examples are illustrative. For copyrighted standards and ISPE guides, the public scope and edition were verified; detailed licensed protocols are not reproduced.
- [GUIDANCE] ISPE — SMEPAC, third edition: Airborne Particle Emissions from Containment Systems.
- [TECHNICAL STANDARD] BSI — EN 689:2018, Workplace Exposure: Measurement of Exposure by Inhalation.
- [OCCUPATIONAL HEALTH REQUIREMENT / GUIDANCE] NIOSH — Occupational Exposure Banding Process for Chemical Risk Management.
- [QRM] ICH Q9(R1) — Quality Risk Management, EMA current version.
- [GUIDANCE] EMA — Health-based exposure limits for shared manufacturing facilities.
