Most Local Exhaust Ventilation (LEV) systems used to control hazardous substances must undergo a Thorough Examination and Test (TExT) at least every 14 months. This requirement comes from Regulation 9 of the Control of Substances Hazardous to Health Regulations (COSHH).
However, 14 months is the maximum interval for most systems—not an automatic entitlement. The process, system condition and maintenance arrangements may require more frequent LEV testing.
COSHH Schedule 4 specifies shorter intervals for certain processes:
Every month: blasting associated with cleaning metal castings during manufacture, and jute cloth manufacture.
Every six months: processes producing non-ferrous metal castings that give off dust or fume.
Every six months: mechanically grinding, abrading or polishing metal articles, excluding wet processes and articles made from gold, platinum or iridium, in a room for more than 12 hours in any week.
These requirements depend on the actual process being carried out.
Yes. The examiner must assess whether the system can continue to perform as intended and contribute to adequate control of exposure.
Using professional judgement, they may recommend a shorter interval—such as three or six months—where deterioration, heavy use or unreliable maintenance arrangements raise concerns about continued performance.
For example, if filter loading is likely to reduce airflow and there is insufficient confidence that filters will be changed when needed, an earlier examination may be appropriate. The report should explain the reason and any maintenance actions required.
More frequent testing does not replace necessary maintenance or make an inadequately controlled process acceptable. The employer remains responsible for keeping the system effective between examinations.
Regular checks should follow the manufacturer’s instructions and the risks associated with the work. These may include checking airflow indicators, hood positioning, damage, blockages and filter condition.
If performance deteriorates or the process changes, seek competent advice promptly rather than waiting for the next scheduled test.
Armstrong Environmental provides independent LEV testing, commissioning and retrospective commissioning, with clear findings and recommendations on suitable examination intervals.
Our team includes LEV Specialists listed on the BOHS Register of Occupational Hygiene Professionals, which is accredited by the Professional Standards Authority (PSA).
Find out more about our LEV testing services or contact our team to discuss your systems.
