What Employers Are Legally Required To Do
Why These Duties Cannot Be Subcontracted
The Role Of The LEV Responsible Person
LEV Maintenance Requirements In Day-To-Day Practice
Why The LEV Logbook Matters
Thorough Examination And Test Is Part Of Employer Responsibility
When Changes Trigger Recommissioning
TR40 As The Practical Reference For Duty Holders
Frequently Asked Questions About LEV Employer Responsibilities
Installing and commissioning an LEV system is not the end of an employer’s legal obligations under the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health Regulations. The employer must ensure hazardous substance exposure is controlled throughout the system's lifespan, not just at installation.
Commissioning only proves the system worked for a specific process and condition on a set date. It does not promise control will continue if the process changes, parts wear, or the system is modified.The continuing nature of that duty is clear. Employers must maintain LEV in an efficient state, in efficient working order, and in good, clean, effective condition. They must ensure the system is used properly, that operators are trained, and that Thorough Examination and Test is carried out at the required intervals.
COSHH LEV requirements impose practical legal duties on the employer. To remain compliant, the employer must ensure the LEV is maintained in an efficient state, in efficient working order, and in good, clean, effective condition.
In practice, that duty has three separate but related elements:
A system that is still physically present but has deteriorated through poor maintenance, misuse, or changes to the process does not meet the legal standard. Merely having "air moving" is not enough; the control must be as effective today as it was on the day of installation and achieving its required design performance.
The employer must also ensure the system is used properly. That means more than simply having the LEV switched on. Operators need to understand how the system works, how to use it correctly for the process and the hazardous substance involved, and what checks they are expected to carry out.
Employers must provide training, verify that effective control is demonstrated during commissioning, and ensure Thorough Examination and Test is carried out at the required intervals.
These duties also extend to documentation and oversight. The employer should ensure that the LEV records identify the hazardous substance being controlled, state the agreed control benchmark, include a commissioning report, provide an O&M manual for the system as a whole, and maintain a logbook for routine checks, maintenance, and training records.
Together, COSHH LEV requirements define compliant LEV management in practice. They apply from when the system enters service and throughout its operational life.
A common misunderstanding is that appointing competent specialists to design, install, commission, maintain, or test an LEV system transfers legal responsibility for its effectiveness. It does not. Ultimate legal responsibility for effective LEV and for the control of hazardous substances remains with the employer.
That distinction matters in practice. Employers can, and often must, appoint specialists to perform roles throughout the LEV process. They may appoint a designer for specifications, a commissioning engineer for control demonstration, a maintenance engineer for work, and a TExT assessor for examination and test.
These appointments help meet the employer’s duty, but do not fulfil it. The employer must ensure the right, competent people are appointed, and the system remains suitable for the process and hazardous substances used.
The employer stays responsible for outcomes. If the wrong specialist is chosen, if process information is incomplete, if defects are ignored, or if operators are not trained, responsibility does not shift to the contractor.
The employer’s role is ongoing accountability: appointing competent people, providing the necessary information, acting on findings, and ensuring proper system management over time.
Employers should appoint an LEV responsible person for each item of LEV within the organisation. In a smaller business, this may be a senior individual, such as a director. In a larger organisation, it may be a nominated employee with the authority and capability to manage the system in practice. The role matters because effective LEV does not manage itself.
Between commissioning, maintenance, and statutory examination, someone within the organisation must ensure the system is used correctly and that the oversight required by the employer is undertaken. In practice, the LEV responsible person should:
The role also requires awareness of change. If the process changes, different substances are used, or the LEV is modified, the responsible person must review the risk assessment and inform the TExT engineer of any changes since commissioning or the last examination. If control changes, recommissioning may be needed.
That makes the LEV responsible person central to keeping the system aligned with the work it is supposed to control.
LEV maintenance requirements sit within the employer’s legal duty to keep the system in an efficient state, in efficient working order, and in good, clean, effective condition. Compliance depends on maintaining that standard continuously, not only at commissioning or shortly before a Thorough Examination and Test.
In practice, maintenance operates at two levels. The first is routine checking in day-to-day use. Before and during operation, those using the system should be alert to physical damage, blockages, unusual noise or vibration, dust deposits, full collection vessels, and other signs that the LEV may no longer be working as intended. Those checks matter because they are often the first indication that control is slipping, and they should be recorded in the LEV logbook.
The second level is planned, and preventative maintenance is carried out by competent personnel. This goes beyond what operators can reasonably identify in normal use. It includes checking system performance, cleaning and decontamination where needed, troubleshooting mechanical or electrical faults, and replacing components in line with the O&M manual and the manufacturer’s recommendations.
Where the LEV serves higher risk processes or includes ATEX or DSEAR-rated equipment, maintenance must be carried out with the appropriate level of competence and control.
Faults identified at either level must be acted on promptly. A defect that is recorded but not repaired does not meet the employer’s duty. Where a fault impairs the system’s ability to provide effective control, the implications for continued use must be assessed and addressed.
Maintenance sits at the centre of ongoing compliance. It is how the employer makes sure the LEV continues to control exposure in real working conditions, rather than relying on the fact that it once did so.
The LEV logbook is where ongoing management is recorded. It should show routine checks, maintenance, defects, repairs, and training. Without it, showing active management between commissioning and Thorough Examination and Test is difficult, and examiners cannot see the recent history.
More than just a formality, the logbook is the main evidence that the employer’s duties are being met in practice. Checks should be recorded when they are carried out, with names, dates, and enough detail to show what was found and what action was taken. That matters because an incomplete, out-of-date, or missing logbook may suggest that the system has not been properly managed, even where some work has been done.
It also matters because the logbook supports follow-up and accountability. It should identify the LEV responsible person, show who defects should be reported to, and provide a clear record of whether reported issues were acted on. In practice, it is a live document that should be kept up to date throughout the life of the system, not filled in retrospectively when a test or inspection is due.
Periodic Thorough Examination and Test is one element of the employer’s overall duty to manage LEV effectively. Responsibility rests with the employer to ensure it is carried out at the required intervals as part of their continuing duty to control exposure to hazardous substances.
The legal obligation lies with the employer as the duty holder, not with the engineer conducting the examination. The employer must ensure the examination is properly arranged, supported, and acted on.
That matters because a valid TExT depends on more than the visit itself. The examiner needs access to the commissioning report, the O&M manual, the LEV logbook, and other relevant records to assess current performance against the original basis of control.
If those records are missing, incomplete, or out of date, the value of the examination is weakened, and the employer is in a poorer position to show that the system has been properly managed between tests.
The employer is also responsible for what happens after the examination. If the report identifies defects, deterioration, or recommendations for corrective action, those findings need to be reviewed and acted on. A TExT report is only useful if it leads to the right decisions about maintenance, repair, continued use, or further investigation.
In practice, ensuring that Thorough Examination and Test takes place at the right time, with the right supporting records, and with proper follow-up is part of the employer’s wider responsibility for keeping LEV effective over time.
Recommissioning may be required whenever the original control basis no longer reflects how the LEV is actually being used. That can happen when the process changes, when different materials or hazardous substances are introduced, when production patterns alter, or when the LEV system itself is modified. A system that was once shown to provide effective control cannot be assumed to remain effective if the conditions on which that control depended have changed.
In practice, employers should treat change as a trigger for review, not as a minor operational detail. Changes to machinery, hood arrangements, ductwork, filters, air movers, discharge arrangements, controls, or make-up air can all affect performance.
The same is true when the process becomes more intensive, when substances with different properties are introduced, or when working methods change. In each case, the employer needs to review the risk assessment and determine whether the existing LEV continues to provide effective control under the revised conditions.
This is where weak practice often appears. A modification may seem minor because the system still runs and airflow is still present, but that does not prove the original benchmark remains valid. If the basis of control has changed, competent advice should be sought, and recommissioning may be needed to establish whether the system still performs as required.
Properly treating change is part of ongoing LEV management. It is how employers ensure that control remains aligned with the work being done, rather than relying on evidence that applies only to an earlier version of the process or system.
Managing LEV properly requires more than a basic understanding of what the system is supposed to do. Duty holders need to understand how effective control is defined, what must be demonstrated at commissioning, what must be maintained in day-to-day use, what records must be kept, and how periodic Thorough Examination and Test fit into the wider compliance picture.
That is where TR40 adds value. It brings the full LEV lifecycle together in one structured guide, from roles and responsibilities through design, commissioning, training, maintenance, documentation, testing, and change management.
For employers, responsible persons, and others with practical accountability for airborne contaminant control, it provides a more complete reference for managing LEV as an ongoing control measure rather than treating it as a one-off installation.
For duty holders who need to understand not just what LEV is, but what proper management of it actually demands, TR40 provides the fuller technical reference across the life of the system.
The employer, as the system owner and duty holder, retains ultimate legal responsibility for ensuring that the LEV provides effective control of hazardous substances. Competent specialists may be appointed to design, commission, maintain, or examine the system, but the employer’s overall responsibility cannot be transferred to them.
An employer can appoint competent contractors to carry out specific technical tasks, but cannot subcontract the ultimate duty to control exposure. The employer remains responsible for selecting competent people, providing accurate process and hazard information, reviewing their findings, and ensuring that required actions are completed.
The LEV responsible person oversees the day-to-day management of the system. Their role includes ensuring operators are trained, checking that routine inspections are completed, maintaining the LEV logbook, coordinating repairs and maintenance, and following up recommendations made in commissioning and Thorough Examination and Test reports.
The employer must ensure that the LEV is maintained in an efficient state, in efficient working order, and in good, clean, effective condition. This includes routine operator checks, planned preventative maintenance, prompt repair of defects, cleaning and decontamination where required, and replacement of worn components in accordance with the system O&M manual.
Operator checks should be carried out at the frequencies stated in the LEV system O&M manual and logbook. Depending on the system, these may include checks before use and scheduled daily, weekly, or periodic inspections. Their purpose is to identify damage, blockages, unusual noise, vibration, dust deposits, full collection vessels, or other signs that performance may be deteriorating.
Employers should retain the process risk assessments, commissioning report and benchmark data, system O&M manual, LEV logbook, operator training records, maintenance and repair records, and Thorough Examination and Test reports. These documents show what the system was intended to achieve and how it has been managed throughout its operational life.
LEV systems must be thoroughly examined and tested at suitable intervals, with a maximum interval of 14 months. Some processes and applications require more frequent examination. The appropriate interval should be determined by reference to the applicable COSHH requirements, Schedule 4 of the COSHH Approved Code of Practice, and the risk assessment.
No. Maintenance and Thorough Examination and Test are separate processes. Maintenance is the ongoing work required to keep the system in good condition. Thorough Examination and Test is the formal assessment of whether the LEV is still providing effective control at that point in time.
Recommissioning is required where changes to the process, hazardous substances, working methods, production conditions, or LEV system affect the original basis of control. This may include changes to hoods, ductwork, filters, air movers, controls, discharge arrangements, or make-up air. Where a component is replaced on a genuine like-for-like basis, full recommissioning may not be necessary, but a sufficiently detailed Thorough Examination and Test should confirm that effective control is maintained and that the previous commissioning parameters remain valid.
Where there is no commissioning report proving that the LEV provides effective control, retrospective commissioning must be carried out. Without valid commissioning evidence, there is no reliable benchmark against which current system performance can be compared during Thorough Examination and Test. Retrospective commissioning establishes the intended performance criteria, demonstrates whether effective control is achieved, and provides benchmark data for future examinations.
The defect should be recorded in the LEV logbook, reported promptly to the responsible person, and assessed to determine whether effective control has been affected. The employer should arrange competent repair and consider whether work can continue safely while the fault remains. Further testing or recommissioning may be required before the system is returned to normal use.
Effective control means that the LEV controls exposure to the hazardous substance in practice for the actual process, operators, and working conditions involved. The presence of airflow alone is not sufficient. Performance should be demonstrated against the agreed control benchmark during commissioning and checked throughout the life of the system.