COSHH essentials for construction sites: a plain-English guide
If you run a construction site, you're dealing with hazardous substances every day. Silica dust from cutting blocks. Diesel fumes from plant machinery. Solvents from paints and adhesives. The list goes on.
COSHH, the Control of Substances Hazardous to Health Regulations 2002, is the legal framework that tells you what you need to do about it. And honestly, it's not as complicated as people make it sound.
We deal with a lot of construction firms at Colbrook, and the same questions come up again and again. What counts as a hazardous substance? Do I need a written assessment for everything? What PPE do I actually need to provide?
What COSHH actually requires
COSHH applies to any substance that could harm someone's health. That includes obvious things like cement dust, paints, solvents, welding fumes, and wood dust. But it also covers less obvious stuff. The dust from cutting concrete blocks. The exhaust from a diesel generator running all day. The silica released when you cut a single kerb stone.
The law says you have to do five things:
1. Identify what's hazardous
2. Decide how people could be harmed
3. Put control measures in place
4. Make sure those controls actually work
5. Tell your workers what they need to know
That's the core of it. Obviously each step has more detail, but the principle is straightforward. You can't protect people from what you haven't identified.
The big one: respirable crystalline silica (RCS)
If there's one substance to get right on a construction site, it's silica. HSE estimates that around 500 workers die every year from silica related diseases, mostly lung cancer and COPD. That's more than the number killed in construction accidents, and it tends to get less attention.
Silica is in bricks, concrete, stone, mortar, tiles. Basically anything with sand or aggregate in it. When you cut, grind, or drill these materials, you create fine dust particles that get deep into the lungs. The legal exposure limit (WEL) for RCS is 0.1 mg/m³ averaged over eight hours. That's a tiny amount. Visibly it looks like almost nothing.
The standard advice: use water suppression or an H-class vacuum when cutting masonry. If you're using a Stihl saw on a pavement, it should have a water attachment. If you're grinding inside, you need local exhaust ventilation. And anyone in the vicinity should be wearing respiratory protection, at least FFP3 disposable masks.
We stock respiratory protection at Colbrook, from disposable FFP3 masks to half-mask respirators with replaceable filters. If your teams are cutting or grinding for more than a few minutes a day, it's worth getting the right kit.
Solvents, paints, and adhesives
Construction sites use a lot of products that give off solvent vapours. Floor adhesives, spray paints, concrete sealers, thinners. All of these contain volatile organic compounds that can cause dizziness, headaches, skin irritation, and long term damage with repeated exposure.
The first question to ask is whether you can swap it out. Use a water based product instead of a solvent based one. Plenty of manufacturers now offer low-VOC alternatives that do the same job. If you can't switch, then you need ventilation. On indoor sites, that means mechanical ventilation, not just a window cracked open. For outdoor work, position yourself upwind.
Where ventilation isn't enough, you need the right respirator with an appropriate filter, usually an A2 filter for organic vapours. And don't forget gloves. Solvents can absorb through the skin, so you need gloves rated for chemical resistance, not just general purpose rigger gloves.
Cement and wet concrete
Cement is one of those materials that seems harmless until you've worked with it for years. Wet concrete is alkaline, pH 12 or higher, and prolonged skin contact causes cement burns, dermatitis, and chrome ulceration. It's not an instant thing. It builds up. A bit of mortar on your knee that you wipe off at the end of the day. A splash on your forearm that you rinse under the tap. Over time, it adds up.
The solution is simple: waterproof gloves, waterproof boots, and coveralls that don't trap wet concrete against the skin. If cement gets inside a glove or boot, stop and rinse immediately. We supply chemical resistant gloves and waterproof workwear that handles this kind of exposure.
Diesel exhaust and welding fumes
Diesel engine exhaust emissions were reclassified by the WHO as a Group 1 carcinogen in 2012. That's the same category as asbestos and tobacco smoke. The HSE introduced a tighter workplace exposure limit for diesel exhaust in 2020, so this is a live compliance issue.
On a construction site, the main sources are plant machinery, generators, and delivery vehicles. Where possible, use mains electricity instead of diesel generators. Position exhausts away from work areas. Fit exhaust filters on plant vehicles. And limit the time workers spend near running engines, especially in enclosed spaces.
Welding fumes were also reclassified as carcinogenic in 2019, which means even mild steel welding now requires local exhaust ventilation. If you've got welders on site and they're not using extraction, that needs fixing.
The practical stuff: what PPE do you need?
COSHH follows a hierarchy of controls. PPE is the last line of defence, not the first. But on a construction site, there are plenty of situations where engineering controls aren't practical. A guy cutting kerbs on a roadside can't install a ventilation system.
When PPE is needed, make sure it's the right type and that people know how to use it. A dust mask that doesn't fit is worse than no mask at all, because the wearer thinks they're protected. We see this a lot. Someone straps on a disposable mask that gaps at the nose bridge and carries on cutting concrete, breathing dust the whole time.
If you're not sure what respiratory, glove, or eye protection you need for a specific substance, get in touch. We deal with this stuff every day and can point you at the right thing for the job.
Quick summary for site managers
- Identify what's on site: check product safety data sheets
- Prioritise silica, solvents, cement, diesel fumes, and welding
- Use water suppression and extraction before relying on PPE
- Fit-test any respiratory protection. An ill-fitting mask is a false sense of security
- Keep records of your COSHH assessments and review them when things change
- Train your teams. They need to know what they're dealing with and why the controls matter
COSHH doesn't have to be a bind. Most of it is common sense once you know what to look for. And we're here if you need the gear to back it up.