Mild Steel Welding Fume
COSHH assessment
A COSHH assessment for mild steel welding fume on a UK construction site: what it does to people, how it gets into them, the controls that stop it, the PPE for what is left, and what to do when it goes wrong. Copy it into your assessment and change what does not fit your job.
Hazards to health
Reclassified by IARC (2017) as Group 1 carcinogen, lung cancer. Metal fume fever, occupational asthma, COPD, kidney damage. HSE position (2019): all welding fume requires effective controls regardless of duration.
Routes of exposure
Inhalation
Control measures
- Eliminate where possible (mechanical fixings, prefab off-site).
- LEV at point of arc, on-gun or fume arms within 30cm of plume.
- Indoor welding always requires LEV plus RPE.
- Outdoor welding requires RPE as a minimum.
- Position to avoid breathing zone exposure.
- Air monitoring.
- Health surveillance with lung function for regular welders.
PPE for what is left
- Powered air-purifying respirator (PAPR/airfed welding helmet, TH2/TH3), preferred.
- Otherwise FFP3 or P3 half-mask under standard helmet, Welding gauntlets, Flame-retardant overalls, Safety boots
Emergency procedures
- Move to fresh air.
- Metal fume fever (flu-like onset 4-12 hrs after exposure): rest, fluids, GP same day.
- Burns: cool with running water 20 mins, A&E.
- Eye flash burn (arc-eye): cool moist pads, A&E for assessment.
Questions people ask
Do I need a COSHH assessment for mild steel welding fume?
If the substance is hazardous to health and your work exposes people to it, yes. The Control of Substances Hazardous to Health Regulations 2002, regulation 6, require a suitable and sufficient assessment before the work starts, with the significant findings recorded if you employ five or more. The safety data sheet is an input to the assessment, not a substitute for it. Guidance, not legal advice.
What is the difference between a safety data sheet and a COSHH assessment?
The data sheet is the manufacturer describing the product in general. The assessment is you describing how your people use it on your job: how much, how often, for how long, in what ventilation, with what controls. Two firms using the same tin can have very different assessments.
What is a WEL?
A Workplace Exposure Limit, the maximum airborne concentration averaged over a reference period, set in HSE document EH40. Where one applies to this substance it is stated in the hazards above; where it does not, the duty to reduce exposure so far as is reasonably practicable still stands.
Is PPE enough?
No. COSHH puts PPE last: eliminate the substance, substitute for something less harmful, control at source with ventilation and enclosure, then organise the work to reduce exposure, and only then PPE for what is left. An assessment that jumps straight to gloves and a mask is the kind an inspector questions. Guidance, not legal advice.
How often should it be reviewed?
When the product, the method, the quantities or the people change, if there is any sign the controls are not working, and at least every year or so regardless. Health surveillance may be required where exposure could cause an identifiable disease, such as dermatitis or occupational asthma.
The COSHH assessment writes itself
Pick the substance in the SiteLynx RAMS editor and the COSHH assessment fills in with the hazards, controls and PPE, alongside the HAVS and noise assessments for the tools you chose. Signed on site on a phone. 14 days free.
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