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What is COSHH?

Last updated on 15th March 2024

COSHH stands for the Control Of Substances Hazardous to Health and this refers to a regulation that was brought about to protect workers, and others, from hazardous substances in the workplace.

The current regulation is the COSHH Regulations 2002 (as amended) and it places a duty on employers to prevent, or reduce, exposure to hazardous substances that could result in ill-health in the workplace. This also applies to the self-employed where they bring their own hazardous substances to other people’s premises. As it is a regulation, it is the law, and employers can be prosecuted for not complying with the regulations.

If this is broken down, it means:

  • Control – Refers to control measures which are things that are put in place to prevent or reduce exposure to substances.
  • Substances – These are things that can be natural or artificial and occur in different forms, such as liquids and solids. These can be hazardous.
  • Hazardous – Something that has the potential to cause harm, in this case a substance, to someone’s health.
  • Health – Being free from illness or injury. A person’s wellbeing.

To summarise, the aim is to put controls in place to prevent or reduce exposure to hazardous substances that could cause harm to a person’s health.

coshh hazardous substances

What are hazardous substances?

A hazardous substance, as outlined in COSHH legislation, is a substance that can cause harm to a person’s health. What makes a substance hazardous? It is the properties of the substance, the surrounding conditions and how it interacts with the human body that determine how hazardous a substance is.

Hazardous substances can be natural or artificial in origin and examples are as follows:

  • Chemicals, preparations and mixtures – These are substances that are manufactured and have a wide range of uses. They are used for specific work activities, e.g. paints, oils, solvents and fuels. Chemicals can also be mixed together in the workplace. Some of these chemicals can be very hazardous.
  • Substances produced by the work being carried out – Work activities can produce hazardous substances as part of a process, e.g. welders use high temperatures to melt metals and this produces fumes.
  • Biological agents – These can be microorganisms (microscopic) such as bacteria, fungi and viruses. These can be naturally occurring in the environment or can be transmitted by animals and humans. This also includes parasites, such as mosquitoes, as they can transmit pathogens through bites.
  • Natural substances – Includes naturally occurring substances in their original form or processed. For example, flour appears to be innocuous and it is used frequently in the workplace and at home. It can actually be classed as being hazardous to health as it is a fine material and it can be readily inhaled into the lungs. Over time, exposure can cause breathing difficulties. Other natural substances include some plant materials. Some plants can irritate the skin and can even cause burns.

What forms of hazardous substances are covered in COSHH legislation?

Substances can occur in many forms, and the extent of exposure to a hazardous substance will depend on the type of form. Forms of substances can include:

  • Solids – Are solid in form and are generally less hazardous in their original state, but can become more hazardous when processed. For example, a block of wood in itself would be non-hazardous, but when it is cut, it becomes hazardous due to the wood dust that is produced. The dust can be inhaled, which can result in ill-health. You will look at how hazardous substances can enter the body later in the unit.
  • Liquids – Substances that are not a solid but free-flowing, e.g. liquids such as cleaning chemicals (bleach) and flammable liquids such as petrol/diesel.
  • Dusts – Dusts are particles of a certain size, and it is important to note that all dusts can be hazardous, at a certain concentration, as they can be breathed in, e.g. dusts from flour in catering, dusts from wood cutting in carpentry and dusts from cutting concrete.
  • Fibres – Are small threads of a substance and can be artificial or natural. Fibres can be inhaled into the lungs, e.g. textiles, fibre glass and asbestos.
  • Mists – In you are out on a misty day and the light is shining, you will see water droplets if the air and your clothing may become damp. Mists can also be created through work processes where droplets of a substance become suspended in the air, e.g. spraying paint is a vehicle workshop or through heating a substance such as oil.
  • Fumes – Fumes are small solid particles that are created through a process, usually where heat is involved, e.g. fumes from welding and fumes from vehicle exhaust emissions.
  • Vapours – When a liquid or solid is under pressure, it can produce small droplets of liquid, in a gas form, at a normal temperature, e.g. vapours from the use of solvents such as paint thinners.
  • Gases – A gas is a substance that can fill a space by expansion and is not a liquid or a solid, e.g. oxygen, carbon dioxide, carbon monoxide and acetylene.
COSHH dust heath and safety

Reasons for controlling substances hazardous to health

Hazardous substances in the workplace can cause ill-health to workers and to others. They can affect a person’s health in a number of ways, as you have seen. In addition to keeping workers healthy and safe, there are other good reasons for the controlling of substances hazardous to health.

Having a better understanding of legal requirements and complying with the COSHH Regulations will keep an employer on the right side of the law and will prevent enforcement action being taken against them. If an employer breaches the regulations, they could be issued with enforcement notices or even prosecuted, which could result in imprisonment and/or a fine. An organisation cannot recoup these costs and it would be a substantial loss for the business. In addition, enforcement notices and prosecutions are usually publicised. This could affect the company’s image and may result in a loss of business. Employees looking for a new role may also disregard the company if they have a poor health and safety record and do not follow COSHH best practice.

Which workers are at a higher risk?

Hazardous substances can be found in an array of workplaces. The following examples of workers that are at a higher risk are:

  • Construction Workers and Tradesmen – People who work in the construction or building industry can be exposed to a number of hazardous substances. These can include concrete, brick and plaster dusts, fumes from welding, asbestos fibres, lead from old paintwork, and numerous chemicals such as paints, solvents, fuels, oils and greases. Wet cement can also cause burns to the skin.
  • Agricultural Workers – Agricultural workers can be exposed to biological agents from being in contact with animals. Viruses, bacteria and fungi can be transmitted to humans from animals, e.g. leptospirosis (Weil’s disease) is a bacterial infection that humans can acquire after contact with water contaminated with rat and livestock urine.
  • Cleaners – Cleaners work with a number of cleaning chemicals such as bleaches, descalers and cleaning sprays. They can also be exposed to other substances when they are cleaning, e.g. biological agents from body fluids.
  • Mechanics – Mechanics who work in vehicle workshops can be exposed to a wide range of hazardous substances. These can include substances such as fuels, oils, greases, paint spraying, welding fumes, exhaust emissions from vehicles and vehicle cleaning products.
  • Medical and Laboratory Workers – Those who work in hospitals, care homes and doctors are at risk of exposure to biological agents (viruses/bacteria). They are also exposed to various drugs and medicines which could be hazardous to their health.
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About the author

Eve Johnson

Eve Johnson

Eve has worked at CPD from the start, she organises the course and blog production, as well as supporting students with any problems they may have and helping them choose the correct courses. Eve is also studying for her Business Administration Level 3 qualification. Outside of work Eve likes to buy anything with flamingos on it, catching up with friends, spending time with her family and occasionally going to the gym!



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