Hot-Applied Bitumen / Mastic Asphalt
COSHH assessment
A COSHH assessment for hot-applied bitumen / mastic asphalt 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
Severe thermal burns (working temp 180-230°C), bitumen fume, IARC Group 2B carcinogen, eye and respiratory irritation, fire risk. Steam explosion if water enters hot bitumen kettle. WEL for bitumen fume 5 mg/m3 (cyclohexane-soluble fraction).
Routes of exposure
Skin contact (thermal), Inhalation (fume), Eye contact
Control measures
- Modern alternatives (cold-applied, single-ply) preferred where spec permits.
- Kettle on stable level base, away from openings, with flame failure cut-off.
- No water near kettle, covered in rain.
- Lid on between draws.
- Bucket transfer with safe lid.
- Ventilation in any enclosed area.
- Fire extinguisher (foam/CO2) within 5m.
- Trained operatives only, kettle competence verified.
- Adjacent tasks halted during pours.
PPE for what is left
- Heat-resistant gauntlets (long cuff), Full face shield, FR overalls (no synthetics, they melt), Safety boots laced over trouser legs, P2 fume mask in poorly-ventilated areas
Emergency procedures
- Burns: cool affected area under cool running water for 20 minutes, do not attempt to remove adhered bitumen, it acts as a sterile dressing.
- 999 for any burn larger than a 50p coin or to face/hands/joints.
- Eye splash: cool water irrigate 20 mins, urgent A&E.
- Fire: foam/CO2, never water on a bitumen fire.
- Steam release from kettle: evacuate, clear area until cooled.
Questions people ask
Do I need a COSHH assessment for hot-applied bitumen / mastic asphalt?
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. For this substance: WEL for bitumen fume 5 mg/m3 (cyclohexane-soluble fraction).
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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