How do you do a COSHH assessment on a building site?
A COSHH assessment is a check of the hazardous substances your work uses or creates, who could be harmed, and the controls you will put in place. HSE breaks it into steps: find the hazards, assess the risks, control them, record what you did and review it.
What counts as a hazardous substance
HSE says a substance hazardous to health covers chemicals and products that contain them, airborne materials such as fumes, dusts, vapours, mists and gases, and biological agents such as the germs that cause leptospirosis. A simple test from HSE: if the packaging carries a hazard symbol, treat it as hazardous.
On a building site, the dust your work creates is the one that gets missed, because it never comes in a labelled tin. HSE flags:
- Silica dust, from cutting, drilling or chasing concrete, block and paving. HSE says a cut-off saw on paving, blocks and kerbs can produce very high levels of silica dust.
- Wood dust, from cutting and sanding. HSE says it causes asthma, and that carpenters and joiners are four times more likely to get asthma than other UK workers.
- Cement, which can cause burns and dermatitis from wet mixes, and dust from dried concrete and mortar that can cause serious lung disease.
Lead, asbestos and radioactive substances sit outside COSHH because they have their own regulations.
Safety data sheets
Under HSE guidance, suppliers must give you an up-to-date safety data sheet for any chemical that is dangerous for supply. Ask for it before the product reaches site, and read the hazard, handling, storage and emergency sections.
HSE is clear that a safety data sheet is not a risk assessment. It tells you about the product; you still have to assess how your people will use it, in which place and for how long. If in doubt, HSE says to contact the supplier.
The steps HSE gives
- Identify the hazards. Check labels and data sheets, and include substances your own work produces, such as dust from cutting or grinding, and skin contact.
- Assess the risks. Decide who might be harmed and how, whether by breathing, skin contact or swallowing, how often and for how long. Include contractors and visitors.
- Control the risks. Work through the measures below.
- Record the assessment and the actions you took.
- Review it, and check that the controls are working.
Control measures
HSE says to prevent exposure at source first, where you can. Its order of preference runs from eliminating the substance, to changing the substance or the process, to engineering controls such as enclosure and local exhaust ventilation, to safe ways of working, with PPE last. HSE warns against reaching for PPE automatically.
- On-tool extraction: for dusty tools, HSE recommends an H or M class extraction unit with the flow rate right for the task, tight hose connections and regular checks. Extraction equipment should be tested by a competent person at least every 14 months.
- Water suppression: on a cut-off saw, use a water attachment on a pressurised supply. HSE notes that water does not capture all the silica, so RPE is still needed as a back-up.
- RPE: for wood dust and paving cutting, HSE points to a minimum assigned protection factor of 20, such as an FFP3 mask. Tight-fitting masks need a face-fit test for each wearer and each type of mask, done by a competent person, and the wearer must be clean-shaven. HSE says RPE that does not rely on a tight seal is available where a beard is worn for religious or similar reasons.
- Cement: waterproof gloves suitable for alkaline substances, boots and trousers that keep it out, prompt washing, an eyewash, and skin checks.
- Cleaning: vacuum, do not sweep.
Recording and reviewing
HSE says that with five or more employees you must record the assessment. With fewer than five, HSE still advises writing down the steps you took to identify the risks. Record the actions you took to protect health, and update the record when things change.
Review it regularly. HSE says to review when the controls may no longer be working, when staff, processes, substances or equipment change, and after problems, accidents or near misses. For dust and cement, HSE also suggests considering health surveillance, such as skin checks for cement work. Check with HSE or a competent adviser if you are unsure what your job needs.
Sources
- HSE: How to carry out a COSHH risk assessment
- HSE: What is a substance hazardous to health
- HSE: Chemical safety data sheets
- HSE: COSHH, what you need to do
- HSE: Principles of good control practice
- HSE: Construction dust, cutting and sanding wood
- HSE: Construction dust, cutting paving blocks, kerbs and flags
- HSE: Cement
- HSE: Fit testing basics