Welding fume from MIG welding mild steel in a workshop
Since 2019 HSE has treated all welding fume, including mild steel, as carcinogenic. Local exhaust ventilation is expected for all indoor welding, with RPE where extraction cannot capture the fume. This example covers a fabricator MIG welding mild steel frames. Draft, not yet reviewed.
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Why these controls
The primary control is extraction at the torch or an extraction arm positioned close to the weld. General workshop ventilation is not enough. The extraction system needs a 14 monthly thorough examination and test.
RPE is added for welding in awkward positions where the arm cannot be placed, and for any welding of stainless or galvanised steel, which produce more hazardous fume. A powered air respirator built into the welding helmet is the usual choice.
Health surveillance is required. As a minimum, a respiratory questionnaire at the start and annually, with lung function testing where the occupational health provider advises.
This document is a starting point. The employer must check it against the actual workplace, the product safety data sheet and current HSE guidance before relying on it. It is not an HSE approved document.
COSHH assessment
Control of Substances Hazardous to Health Regulations 2002, regulation 6
| Company or site | Northgate Fabrications Ltd |
|---|---|
| Location | Fabrication workshop |
| Assessor | Steve Kowalski, Works Manager |
| Reviewed by | Steve Kowalski, Works Manager |
| Approved by | — |
1. Substance
| Name | Welding fume (welding smoke, mild steel welding fume, stainless steel welding fume) |
|---|---|
| Supplier | — |
| Quantity held on site | — |
| Physical form | fume |
| Safety data sheet | Not attached. Obtain the current sheet from the supplier and keep it with this assessment. |
| Signal word | None |
| Pictograms | No pictograms |
2. Hazards
HSE safety alert, February 2019: all welding fume is carcinogenic. Local exhaust ventilation is expected indoors and RPE where LEV alone does not control exposure, including outdoors. There is no single WEL for the fume; component limits from EH40 apply: manganese 0.2 mg/m³ inhalable and 0.05 mg/m³ respirable, chromium VI 0.01 mg/m³ (0.025 mg/m³ where process generated), nickel 0.1 mg/m³ soluble and 0.5 mg/m³ insoluble, iron oxide fume 5 mg/m³ with a 10 mg/m³ short term limit.
This substance is a carcinogen or mutagen. Under COSHH regulation 7(7) exposure must be reduced as low as is reasonably practicable, not just kept below any workplace exposure limit. Health surveillance and exposure records are expected.
| Routes of exposure | inhalation |
|---|---|
| Workplace exposure limit | No WEL recorded in this library entry. Check SDS section 8 and EH40; exposure must still be controlled. |
3. How the substance is used
| Task | MIG welding mild steel frames and brackets on a fabrication bench and occasionally on the floor for large items |
|---|---|
| Who is exposed | Two fabricators. Other workshop staff within 5 m |
| At particular risk | None identified |
| Frequency | Daily |
| Quantity used | 4 to 6 hours of arc time per welder per day |
| Duration | Most of the shift |
| Ventilation | Good, windows or mechanical ventilation |
| Spray, heat or mist | Yes |
| Storage | Not applicable. Welding wire and gas cylinders stored per supplier guidance |
| Store away from | — |
4. Risk rating
| Before controls | High, 25 out of 25 (likelihood 5 × severity 5) |
|---|---|
| With controls in place | Medium, 10 out of 25 (likelihood 2 × severity 5) |
5. Control measures in place
Engineering controls
- Local exhaust ventilation captures it at source. Extraction at the point where dust, fume or vapour is made. Thoroughly examined and tested at least every 14 months, with the report kept, as COSHH regulation 9 requires.
Working practices
- Staff are trained on this assessment and the safe method. Everyone who uses it has been told the hazards, the safe way to use it, the controls and what to do if something goes wrong. Training is recorded. Required by COSHH regulation 12.
- The safety data sheet is available to staff. The current data sheet is kept where staff and first aiders can find it, and is checked when the product or supplier changes.
- It is stored safely. Original labelled containers, closed, upright, in a cool ventilated place away from incompatible substances, food and public access.
- Only trained staff use it, for as short a time as possible. Use is limited to the people who need to do the task, exposure time is kept short and tasks are rotated where practical.
- Health surveillance is in place. Skin checks, or a breathing questionnaire and lung function tests through an occupational health provider, as COSHH regulation 11 requires for this hazard.
- Exposure is monitored. Air monitoring has been done, or is scheduled, to check exposure stays below the workplace exposure limit (COSHH regulation 10).
Personal protective equipment
- Staff wear eye protection. Goggles to EN 166 where there is a risk of splashing. Safety glasses are not relied on for corrosive liquids.
- Staff wear respiratory protection. RPE with the filter type in the data sheet. Tight fitting masks have been face fit tested. Follows HSE guidance HSG53.
6. Decisions
| Substitution considered | — |
|---|---|
| Exposure adequately controlled | — |
| Health surveillance | — |
| Exposure monitoring | — |
7. Further action required
None identified at this revision.
8. First aid, spillage and disposal
Inhaled: fresh air. Flu like symptoms after welding galvanised steel (metal fume fever) need medical advice. In an emergency call 999. For advice call NHS 111.
| Spillage | Follow section 6 of the safety data sheet. |
|---|---|
| Disposal | Follow section 13 of the safety data sheet. Waste leaves site as hazardous waste through a licensed carrier. |
9. Notes
Extraction arms at both benches, tested 14 monthly. Powered air welding helmets for floor work and for any stainless or galvanised steel. Annual respiratory questionnaire.
Hazard data from the ECHA classification and labelling inventory and HSE EH40/2005. Check the supplier safety data sheet for the exact product and concentration you use. Review by the next review date, and sooner if the product or supplier changes, the task or the people doing it change, there is a spill or incident, anyone reports symptoms, or new information arrives from the supplier or HSE. This assessment is a starting point; the employer must review it against the actual workplace before relying on it.
