COSHH Regulations

COSHH Regulations

COSHH (Control of Substances Hazardous to Health) is the law that requires employers to control hazardous substances so they do not cause ill health.  The third biggest source of all air pollution is the workplace.

Each employer is responsible for taking effective measures to control exposure to dust, fumes and other airborne contaminants to protect employee health.  Major changes in working practises or buildings can be avoided as a self-contained high performance air filtration unit at the source of the contamination will often provide an excellent solution.

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Frequently Asked Questions

The Control of Substances Hazardous to Health (COSHH) Regulations require employers to control any substances present in the workplace which could be hazardous to health.

Most workplaces will use or create such substances.  Exposure to a hazardous substance can occur through breathing, skin contact, injection into the skin, or swallowing.  The law also applies to self-employed people if they may expose others to a hazardous substance during the course of their work.

The broad categories of hazardous substances covered by COSHH guidance are:

  • Chemicals
  • Dusts
  • Vapours
  • Microorganisms
  • Gases

An employer needs to be aware of the health hazards which may be present in their workplace.  Are there processes which emit dust, fumes, vapours, mists or gases?  Which processes or tasks can potentially lead to exposure?  Are substances that the HSE has given a WEL present in your workplace?

These questions are the starting point for making your COSHH assessment together with guidance from the Health and Safety Executive, with examples of the level of detailed planning needed available on their website (link to: An assessment is needed for each potentially hazardous substance, which involves deciding how harm is to be prevented. Whatever the control measures required; improved ventilation, specialised storage or dedicated air filtration, they must be in operation and well maintained.

Employees require information, instruction and training, with health monitoring and surveillance also necessary from time to time.  This is the case when it is known that a specific disease like cancer or asthma is associated with exposure to a particular substance. Employers also need to plan for emergencies, such as leaks of solvent or gas escapes.

COSHH guidance covers substances that may cause a health risk.  These substances take many forms and include:

  • Chemicals
  • Products containing chemicals
  • Fumes
  • Dusts
  • Vapours
  • Mists
  • Nanotechnology
  • Gasses
  • Biological agents

Health hazards are not limited to substances labelled as ‘hazardous'. Some harmful substances can be produced by a manufacturing process, for example; wood dust, silica dust or VOC gases from printing.

How might workers be exposed? Think about the route into the body (whether the substance can be breathed in, get onto or through the skin or can even be swallowed) and the effects of exposure by each of these routes.  Consider anyone else who could be exposed including maintenance workers, contractors and other visitors with a potential for exposure.

Following a risk assessment which has identified which harmful substances are present, and how workers can be harmed, preventing exposure is the priority.

Do you really need to use a particular substance, or is a safer alternative available?

Can you change the process to eliminate its use or avoid producing it? If this is not possible, you must put in place adequate control measures to reduce exposure.

When there is no alternative to using a hazardous substance, employers and employees must work together to minimise exposure, based upon the information and advice they have from their risk assessment and safety data sheet.  Methods to mitigate the risks include:

  • Total or partial enclosure of the hazardous substance
  • Adequate ventilation within the premises
  • Local exhaust ventilation system at the source
  • Appropriate personal protective equipment, such as respirators, masks, and gloves
  • Train in the storage and handling of hazardous substances
  • Implement standalone high performance air filtration units

The COSHH Regulations require employers to assess the risk to their employees, and to prevent or adequately control those risks.  Judging the exposure to certain substances can be straightforward and mitigation measures obvious.

When small amounts of material in a work process are involved, even if these are harmful, and when there is little chance of it escaping, the risk is low.

The risk of the same substance in a different process – such as cleaning and disposal – will be higher as the substance may become airborne and potentially be inhaled.

When the task involves larger amounts of material, with obvious leaks, both the potential exposure and risk is greater. Whether the substance is harmful or not, the need to control it is clear. Decide what measures you need to take, and when.

Companies with five or more employees must record the assessment but it is wise to write down what steps you have taken to identify the risks regardless of the size of the organisation. The critical element is the list of actions to control the risk.  The HSE has COSHH guidance and risk assessments for different industries on: The HSE site also has COSHH guidance relating to good risk control practise:

Failure to comply with COSHH regulations is a crime punishable by fine and leaving the employer open to civil claims.  The HSE together with the local authority enforces COSHH under the Health and Safety Act.

There have been around 500 prosecutions each year in the recent past, most of them successful.

While COSHH has its WELs as a guideline, in REACH there is a Derived No Effect Level (DNEL) – which is a benchmark rather than an exposure limit - for a substance.  The manufacturer or importer uses the DNEL to identify correct risk management measures (RMM) and also exposure scenarios for various tasks and procedures.

This information appears on the REACH Safety Data Sheet.  If this guidance is followed, then an employer will comply with the DNEL.  If employers stick with COSHH guidelines, they will comply with WELs.  COSHH guidelines and RMM under REACH should be aligned.

REACH stands for Registration, Evaluation, Authorisation and restriction of Chemicals and is a complex and evolving piece of European legislation which aims to provide more information about known hazardous substances and those which can be potentially hazardous.

REACH covers chemicals used in the workplace and in consumer products. Manufacturers making large quantities of substances - 10 or more tonnes per annum - are required to register and to provide detailed information on each product to be passed down the supply chain.

The scheme is intended to provide more detailed safety data sheets and information on potential exposure scenarios.  Employers should understand their position within the supply chain and their responsibilities under REACH.

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