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LEV testing - frequency
Every extraction system that controls a hazardous substance has to be examined and tested on a legal cycle. Here is where the 14 months comes from, what the test involves, and where the interval is shorter than you think.
The short answer
Under the Control of Substances Hazardous to Health Regulations (COSHH), local exhaust ventilation must have a thorough examination and test at least once every 14 months. That figure is a legal maximum, not a target - many systems need testing more often, and for some named high-risk processes the law sets a much shorter minimum. The employer holds the duty to make it happen.
Where 14 months comes from
COSHH Regulation 9 requires that engineering controls - which is what an LEV system is - are maintained in efficient working order and good repair, and that LEV is thoroughly examined and tested at suitable intervals, and at least every 14 months for most processes.
The 14 rather than 12 is deliberate. A slightly-longer-than-annual interval lets the test date rotate through the year instead of always landing in the same busy week, while still keeping it close to yearly. It is the outer limit, though - not the default. If wear, damage or a change in the process could degrade performance sooner, the test is due sooner.
When it is more often than 14 months
For a set of named high-risk processes, COSHH Schedule 4 sets shorter statutory minimums - some measured in months rather than a year - because the consequences of a control failing are severe. The guidance HSG258 is also clear that testing must be more frequent wherever wear and tear would degrade performance between scheduled tests, or where the risk assessment identifies higher exposure.
So the honest position is that 14 months is the longest you can leave it, not the interval every system should run to. A competent examiner will tell you if yours needs testing more often, and your own risk assessment should drive that too.
What the test involves
A proper LEV test - a thorough examination and test, or TExT - is not a quick look. HSG258, the HSE guidance, structures it in three stages. First a thorough visual examination of the physical condition and integrity of hoods, ducting, filter housings, fans, discharge points and airflow indicators. Second, measurement of technical performance - quantitative readings such as face velocity and capture at the hoods - to check the system is actually controlling exposure. Third, an assessment of whether that control is protecting the people using it.
The output is a report that says, with figures, whether each part of the system is doing its job, plus any remedial actions. That is what turns a test into evidence you can rely on.
The employer's duty
The duty sits with the employer. If your workplace produces dust, mist, fume, vapour or gas that LEV is there to control - welding fume, wood dust, flour dust, solvent vapour, and many more - you must keep that LEV in efficient working order and have it examined and tested on the COSHH cycle.
You must also keep the records. COSHH requires the report of each thorough examination and test, and details of any repairs, to be kept for at least five years. That record is what an HSE inspector will ask to see, and what shows the system has been maintained rather than merely installed.
Questions
Under COSHH, at least once every 14 months for most processes. That is a legal maximum - some high-risk processes named in COSHH Schedule 4 must be tested more often, and any system should be tested sooner where risk or wear demands it.
The slightly longer interval lets the test date rotate through the year rather than always falling in the same period, while staying close to annual. It is the outer limit, not a target.
A thorough examination and test to HSG258 has three stages: a visual examination of the system's condition, measurement of technical performance such as face velocity and capture at the hoods, and an assessment of whether exposure is being controlled.
The employer's. If you rely on LEV to control a hazardous substance, you must keep it in efficient working order and have it examined and tested on the COSHH cycle.
At least five years. COSHH requires the report of each thorough examination and test, and details of any repairs, to be retained - and an HSE inspector can ask to see them.
The LEV is no longer demonstrably controlling exposure, you are in breach of COSHH, and you have no current evidence to show an inspector. Missed or overdue testing is a common enforcement finding.
We will examine and test your local exhaust ventilation to COSHH and HSG258, and set you up on the right cycle.
