The short answer
At least once every 14 months under COSHH regulation 9. A few processes in COSHH Schedule 4 need a test every month or every six months, and the examiner can recommend a shorter interval where a system is working hard or deteriorating fast.
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The question comes up in almost every workshop that has extraction: is it once a year, or something else? The answer sits in two places in the Control of Substances Hazardous to Health Regulations 2002, usually called COSHH, and it is simpler than it looks.
The general rule: at least every 14 months
Regulation 9 of COSHH says that where an employer uses local exhaust ventilation (LEV) to control exposure to a hazardous substance, it must be thoroughly examined and tested. For most LEV the interval is at least once every 14 months.
That applies to almost everything people call extraction: dust extraction on woodworking machines, welding fume arms, fume cupboards, spray booths, oil mist extractors on machine tools, sack tipping hoods in bakeries, and portable units with their own fan. If the extraction is part of how you keep a substance out of people’s lungs, it is in scope.
The 14 months is a maximum, not a target. It gives a margin so that a test planned for the same month every year does not become illegal if a visit slips by a few weeks. Most sites test every 12 months for that reason.
Processes that need testing more often
COSHH Schedule 4 lists a small number of processes where the LEV must be tested more frequently:
| Process | Minimum frequency |
|---|---|
| Blasting carried out in or incidental to the cleaning of metal castings | Every month |
| Jute cloth manufacture | Every month |
| Dry grinding, abrading or polishing of metal articles (other than gold, platinum or iridium) for more than 12 hours in any week | Every 6 months |
| Processes giving off dust or fume in the manufacture of non-ferrous metal castings | Every 6 months |
If any of these happen on your site, check that your test schedule reflects them. A foundry or fettling shop on an annual contract is a common gap.
When the examiner recommends a shorter interval
The examiner can recommend testing more often than the law requires. That usually happens where a system controls something very hazardous, runs heavily, or showed a large drop in performance since the last test. HSE’s commissioning guidance also says the commissioning report should state how often the system should be tested if that differs from 14 months. Treat a shorter recommended interval as the one that applies to you.
Between tests: checks and the logbook
The statutory test is a snapshot. In between, regulation 9 still requires the system to be kept working properly and in good repair. HSE guidance in HSG258 expects regular checks by the people who use it: airflow indicators reading correctly, hoods in the right place, hoses and arms intact, filters emptied and changed on time.
Record those checks in a logbook. Weekly is common for busy systems, monthly for light use. Our note on LEV logbooks sets out what to include.
Planning tests across a site
Sites with several systems often find the due dates drift apart over the years. One joinery shop may have a dust system tested in March, a spray booth in July and a mobile extractor that nobody remembers. Bringing them together on one visit saves money, because travel and report time are shared, and makes the date easier to remember.
To bring them into line, test the latest system a little early rather than letting the earliest one run past 14 months. Then book all of them for the same month every year.
How long to keep the records
Keep a record of each thorough examination and test, and of any repairs carried out as a result, for at least five years. In practice the commissioning report should be kept for the life of the system, because it holds the benchmark figures each test is compared against.
What to do if you are overdue
If your last test was more than 14 months ago, book one now and treat the system as overdue in your risk assessment. An overdue test does not automatically mean the extraction is failing, but you have no evidence that it is working, which is what the inspector or your insurer will ask for.
If there has never been a test, ask the examiner to set benchmark figures on the first visit. Without a commissioning report, there is nothing for later tests to compare against.
Quick checklist
- Find the date of the last test report and add 14 months.
- Check whether any process on site is in Schedule 4.
- Check the last report for a recommended shorter interval.
- Put the next due date in a diary owned by a named person, with a reminder two months ahead.
- Keep weekly or monthly checks in the logbook.
For a rough budget, see the LEV testing cost guide. When you know your due date, use the form below to get a quote from a qualified examiner who covers your area.