COSHH and hazardous substances

This talk is about hazardous substances on this job. COSHH is the Control of Substances Hazardous to Health Regulations. HSE says COSHH covers chemicals, products containing chemicals, fumes, dusts, vapours, mists, gases and asphyxiating gases, and biological agents. If the packaging has a hazard symbol, it is classed as a hazardous substance. Germs that cause diseases such as leptospirosis are in scope too. COSHH does not cover lead, asbestos or radioactive substances, because those have their own regulations. Asbestos is the other talk. Silica dust is still a hazardous substance, and it has its own talk because the controls are specific. Do not let this briefing replace that one.

A COSHH assessment is not only about tins with a symbol. HSE's assessment page says health hazards are not limited to substances labelled as hazardous. The work can produce them. The examples on that page are wood dust from sanding, silica dust from tile cutting, and fumes from welding. If we are cutting, grinding, heating or spraying, we ask what the process is putting into the air, not only what the tub says.

If you are self-employed, HSE's answer is yes, COSHH applies. If you have employees and you control their work, every part applies. If you have no employees, but you take hazardous substances onto other people's premises, all parts apply except those about monitoring and health surveillance. Working alone in a customer's house does not switch the rules off.

Before the assessment, HSE says ask what you do that involves hazardous substances, how they can cause harm, and how you can reduce that harm. Always try to prevent exposure at source. Can you avoid the substance, or use a safer process, such as a water-based product instead of a solvent-based one, or a brush instead of a spray? Can you substitute something milder, or use a vacuum rather than a brush? Can you use a safer form, such as a solid instead of a liquid, to avoid splashes, or a waxy solid instead of a dry powder, to avoid dust? If you cannot prevent exposure, you control it. Control is adequate when the risk of harm is as low as is reasonably practicable. That means the control measures are in good working order, exposures are below the workplace exposure limit where one exists, and exposure to substances that cause cancer, asthma or genetic damage is reduced as low as possible.

The assessment itself is a set of questions, not a form for its own sake. Read the label and the safety data sheet. If in doubt, ask the supplier. Decide who might be harmed and how: breathed in, on the skin, through the skin, or swallowed. Think about how often and for how long, and about maintenance workers, other contractors, visitors and members of the public. Write down what you already do and what else is needed, who will do it, and by when. Substances that have a workplace exposure limit are hazardous to health. The limit is a mark the controls have to meet. It is not a target to work up to.

HSE's order for controls starts with elimination: do you need this substance at all? Then change the process, for example a lower temperature so less vapour is given off, or pellets instead of a dusty powder. Then containment: enclose the work, use closed transfer, and use local exhaust ventilation that is examined and tested every 14 months by someone competent. Restrict access to the people who need to be there. Store materials in the right containers, labelled, with incompatible materials separated. HSE's example is acids and caustics. Plan the waste. Cleaning is part of the exposure, so use a dust-free method: vacuum, do not sweep. Have a way to clear a spill quickly. Personal protective equipment is for when the other controls cannot adequately control exposure, and it is used with those controls, not instead of them. HSE says do not automatically opt for PPE. It is not as reliable or effective as the other measures.

People have to be told the outcome. What the hazard is, any workplace exposure limit, what they must do, the results of any monitoring, and the collective results of health surveillance. They need to know what to do in a spill or an emergency. If a contractor is bringing a substance onto the job, we need to know what it is and how they will stop it harming other people. If you have five or more employees, you must record the assessment. If you have fewer, HSE says it still makes sense to write down the steps you took. Review it when the staff, the process, the substance or the equipment changes, and if people report a problem or there is an accident or a near miss.

On this job today, the question is simple. What are we about to open, heat, cut or spray? Have we read the label? Is the control the one in the assessment, or a mask we hoped would cover it? Who else is in the room, including the customer? If the label is missing, we do not guess. We stop and find out.