Welding fume is a Group 1 human carcinogen (IARC 2017); HSE STSU1-2019 requires LEV for all indoor welding, plus RPE where LEV is not enough and for outdoor welding.
Fabora resources
Welding fume, LEV and extraction control for workshops.
Welding fume is now classed as a human carcinogen, and since HSE bulletin STSU1-2019 all indoor welding of mild steel needs effective engineering controls (usually local exhaust ventilation (LEV)) with suitable RPE where LEV alone is not enough. This guide explains the law, how to control welding fume from the source outward, the RPE that goes with it, and how LEV testing (thorough examination) keeps it working.
Short answer
Welding fume control is a legal duty under COSHH. The aim is a workable setup: capture fume at the source with the right LEV, support it with ventilation and housekeeping, add suitable RPE where needed, and keep the LEV examined and tested.
- Welding fume is a Group 1 human carcinogen (IARC 2017); HSE STSU1-2019 requires LEV for all indoor welding, plus RPE where LEV is not enough and for outdoor welding.
- Controlling exposure is a legal duty under COSHH Regulation 7. Source capture (LEV) usually matters more than dealing with fume after it spreads.
- LEV only helps if it is the right type, positioned properly, maintained, and thoroughly examined and tested (a TExT) at least every 14 months.
- Process changes, coated materials and stainless work change the risk, so the control mix and records need to keep up.
General guidance only. Workshop welding controls still need to be reviewed around the actual process, material, workpiece size, and competent COSHH management in your business.
Practical summary
What to take from this page
Welding fume control is a legal duty under COSHH. The aim is a workable setup: capture fume at the source with the right LEV, support it with ventilation and housekeeping, add suitable RPE where needed, and keep the LEV examined and tested.
General guidance only. Workshop welding controls still need to be reviewed around the actual process, material, workpiece size, and competent COSHH management in your business. For official detail, use the source links later on this page.
Controlling exposure is a legal duty under COSHH Regulation 7. Source capture (LEV) usually matters more than dealing with fume after it spreads.
LEV only helps if it is the right type, positioned properly, maintained, and thoroughly examined and tested (a TExT) at least every 14 months.
Process changes, coated materials and stainless work change the risk, so the control mix and records need to keep up.
The law and the risk
Why welding fume is taken so seriously
Welding fume control is not optional good practice. It is a legal duty driven by a serious health risk.
Welding fume is a carcinogen
In 2017 the International Agency for Research on Cancer classified welding fume as a Group 1 human carcinogen. In 2019, HSE bulletin STSU1-2019 reclassified mild steel welding fume the same way and strengthened what it expects from businesses.
LEV is required for indoor welding
Since STSU1-2019, all indoor welding of mild steel needs effective engineering controls, normally LEV at the arc. Where LEV alone does not adequately control exposure, suitable RPE is also required, and RPE is required for welding outdoors.
It is a COSHH duty
Controlling exposure to welding fume is a legal duty under COSHH Regulation 7: prevent exposure where reasonably practicable, and otherwise adequately control it with the right mix of LEV, ventilation and RPE.
Control approach
What good workshop control usually looks like
A workable setup is normally layered. The exact mix changes with the welding process, the material, and how the workshop is laid out. The related welding risk assessment template linked later on this page is useful when fume control needs to carry through into the wider RAMS pack.
Capture fume close to where it is generated
Bench extraction, extraction arms, or on-torch extraction only help when they are matched to the task and kept where the fume is actually being produced.
Support the process with sensible ventilation and layout
General ventilation, bay spacing, and keeping nearby people out of the fume path all help the main control system do its job.
Use suitable RPE where the task needs it
Some workshop tasks still need respiratory protection alongside extraction, especially where capture is harder, exposure is heavier, or the material brings added risk.
LEV and extraction
LEV points that often make the difference
Many welding fume problems come from extraction that exists on paper but is unreliable in daily use.
Choose the right capture setup
Small bench work, larger assemblies, and mobile fabrication jobs often need different extraction arrangements to be workable and consistent.
Keep hood and torch positioning practical
If the operator has to keep moving the hood, the system needs to be easy enough to reposition often, otherwise the fume escapes back into the breathing zone.
Commission and benchmark the system properly
A new or changed LEV setup needs clear performance information, so the business knows what good looks like and what later checks should be compared against.
Maintain it and test it on time
Damaged ducting, blocked filters, poor airflow, and overdue examinations can quickly turn a good-looking setup into a weak one.
LEV testing
LEV testing and thorough examination
An LEV system only protects people if it is kept working, and the law requires it to be tested.
Test it at least every 14 months
Under COSHH Regulation 9, LEV must be thoroughly examined and tested (a TExT) at least every 14 months, and more often for some higher-risk processes. This is what most people mean by 'LEV testing'.
What the test covers
A competent examiner checks the system still performs to its commissioning benchmark (airflow and capture at the hood, condition of ducting and filters) and that it controls exposure in real use. You get a written report.
Keep the records and in-between checks
Keep the TExT report, plus your own routine checks and any faults and fixes, so you can show the system has been maintained between examinations. LEV Ready is built to keep these asset records, due dates and reports in one place.
Act on overdue or failed tests
An overdue examination, a failed report, or visible loss of capture all mean the control can no longer be relied on. Fix it and re-test before treating the bay as controlled.
Day-to-day management
The workshop routines around the extraction matter as much as the hardware
Even a well-specified system underperforms if the surrounding workshop routine is poor.
Training and supervision
Welders and supervisors need to understand why the controls matter, how to position them, what checks to make, and when to escalate problems.
Housekeeping and secondary dust
Grinding dust, settled contamination, and clutter around extraction points can undermine otherwise sensible workshop control.
Nearby workers and work area boundaries
Think about people working next to the weld bay, not just the person holding the torch. Screening, spacing, and job placement all help.
Review when the work changes
Different metals, coatings, repair work, or larger fabrications can change the exposure picture. The control setup should be reviewed when the process shifts.
What to check
Practical checks for supervisors and workshop leads
A short floor check often tells you more than a long policy note. These are the warning signs worth looking for.
Visible fume escaping the capture point
If the plume is rolling past the hood or the welder keeps leaning into it, the setup is unlikely to be performing well enough in real use.
Extraction switched off or avoided
If people bypass the system because it is awkward, noisy, or in the way, the control arrangement needs attention rather than blame.
Poor condition or missing checks
Damaged hoses, weak airflow, blocked filters, or missing maintenance records are practical warning signs that the setup needs review.
Higher-risk materials or awkward workpieces
Stainless, coated, painted, or large fabricated items can change the exposure picture and may need a different control mix than routine bench work.
Official guidance
Relevant official sources
These links point to the underlying official material. This page is a practical summary, not a replacement for those sources, competent review, or legal advice.
HSE: Welding fume - protect your workers
HSE overview page covering the main health risk and the core control themes for welding fume.
HSE: Controlling the risks from welding
Useful for HSE guidance on risk assessment, control options, nearby workers, and when exposure patterns differ.
HSE: Commission your LEV system
Useful for commissioning, benchmarking, training expectations, and the need for regular examination and testing.
HSE: Clearing the air
Useful plain-English LEV guidance for buying, using, and maintaining extraction systems.
FAQ
Common questions
Short answers on practical use, review expectations, and where this guidance stops.
Important note
Final review, suitability, and approval still remain with the customer's business and the people responsible for the job.
Is welding fume a carcinogen?
Yes. The International Agency for Research on Cancer classified welding fume as a Group 1 human carcinogen in 2017, and HSE reclassified mild steel welding fume the same way in bulletin STSU1-2019. That is why effective controls are now expected for all indoor welding.
Do I need LEV for welding?
For indoor welding, yes. Since HSE STSU1-2019, effective engineering controls (normally LEV at the arc) are required regardless of how long the welding lasts. Where LEV does not adequately control exposure, suitable RPE is also needed, and RPE is required for welding outdoors.
How often should welding LEV be tested?
LEV must be thoroughly examined and tested (a TExT) at least every 14 months under COSHH Regulation 9, and more often for some higher-risk processes. You should also do your own routine checks in between and keep the records.
What is LEV testing (thorough examination)?
LEV testing, or thorough examination and test (TExT), is a check by a competent examiner that the extraction system still performs to its commissioning benchmark (airflow, capture and condition) and adequately controls exposure. It produces a written report and is required at least every 14 months.
What RPE do I need for welding fume?
Where RPE is required, welding fume is typically controlled with FFP3 disposable masks or powered respirators giving an assigned protection factor (APF) of 20. RPE must be adequate and suitable for the task, and tight-fitting masks must be face-fit tested.
Is general workshop ventilation enough on its own?
Usually not. General ventilation helps, but welding fume is best controlled by capturing it at the source with LEV, supported by good layout, supervision and RPE where needed.
Does this page replace a COSHH assessment?
No. This page is a practical summary. The actual workshop setup still needs competent COSHH review around the process, exposure and controls in your business.
Related reading
Continue from here
These links keep the topic moving, either into related guidance or into the Fabora RAMS product pages.
LEV Ready: LEV and extraction asset records
Manage LEV and extraction asset records, examination due dates, QR labels and reports in one place.
LEV records (logbook)
What to record between examinations to show your LEV has been maintained.
LEV testing records
What a thorough examination and test should capture, and how to keep the reports.
COSHH and welding consumables for steelwork teams
The wider COSHH picture around fumes, gases, sprays and consumables.
Welding risk assessment template
Carry fume control through into the welding risk assessment and RAMS pack.