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Understanding COSHH means understanding the Regulations, that is, the law. It also means understanding the various Approved Codes of Practice (ACOP), that is, how the law can be reasonably met. 



The Control of Substances Hazardous to Health (COSHH) Regulations 2002 impose on employers a requirement in law to protect employees against health risks from hazardous substances used in their work. COSHH Regulations specifically require employers to:

  • Identify hazardous substances and practices

  • Assess risks to exposure to hazardous substances in the workplace, and if significant

  • Provide a safe working environment through control of exposure to the hazardous substances

  • Monitor and maintain a safe working environment where hazardous substances are used

A Brief Guide to the Regulations can be obtained from the HSE website here
. The full Regulations can be viewed here.

Answers to Frequently Asked Questions

What are the COSHH Approved Codes of Practice?
The Approved Codes of Practice (ACoP) provide practical advice and examples of good practice. They show how it is possible to apply the goal-setting requirements of the Regulations (that is, what must be achieved) in particular circumstances and hence on how to comply with the law. Not all ACoP are COSHH-related. COSHH-related ACoP include:

  • The General Approved Code of Practice (ACoP) on the Control of Substances Hazardous to Health Regulations 1999 (COSHH)

  • The Control of Carcinogenic Substances ACoP

  • The Control of Biological Agents ACoP

  • The Safe use of Pesticides on Farms and Holdings ACoP

  • The Control of Biological Agents ACoP

  • The Control of Vinyl Chloride at Work ACoP

  • The Control of Substances Hazardous to Health in the Production of Pottery ACoP

  • The Prevention or Control of Legionellosis (including legionnaire's disease) ACoP

  • The Safe use of Pesticides for Non-Agricultural Purposes ACoP

  • The General ACoP applies to all hazardous substances covered by the COSHH Regulations 2002.

The Requirements of COSHH
The HSE suggests there are eight key requirements of the COSHH Regulations. These are: 

Step 1 

Assess the risks

Assess the risks to health from hazardous substances used in or created by your workplace activities.

Step 2 

Decide what precautions are needed

You must not carry out work which could expose your employees to hazardous substances without first considering the risks and the necessary precautions, and what else you need to do to comply with COSHH.

Step 3

Prevent or adequately control exposure
You must prevent your employees being exposed to hazardous substances. Where preventing exposure is not reasonably practicable, then you must adequately control it.

Step 4
Ensure that control measures are used and maintained

Ensure that control measures are used and maintained properly and that safety procedures are followed.

Step 5 

Monitor the exposure

Monitor the exposure of employees to hazardous substances, if necessary.

Step 6 

Carry out appropriate health surveillance

Carry out appropriate health surveillance where your assessment has shown this is necessary or where COSHH sets specific requirements.

Step 7 

Ensure employees are properly informed, trained and supervised

You should provide your employees with suitable and sufficient information, instruction and training.

If carried out systematically, these steps of the COSHH assessment will ensure that an employer will comply with the requirements of the Control of Substances Hazardous to Health (COSHH) Regulations 2002. A brief guide to the Regulations regarding COSHH assessments can be found in the HSE's guidance booklet on COSHH assessments and other publications.

Who is Responsible for making a COSHH Assessment?
Complying with the COSHH Regulations, that is making a COSHH assessment, is the responsibility of the employer. However, the employer will probably delegate responsibility for making the actual assessment to someone who:

  • understands the requirements of the COSHH Regulations (usually together with appropriate Approved Codes of Practice)

  • has both the competence and the authority to obtain all the necessary information in the workplace and source relevant health and safety data

  • has both the knowledge and the skill to correctly judge between significant and trivial risks to health

  • has the authority to implement and monitor control measures and the appropriate training and health surveillance of personnel

Remember, it is usually the case that no one person has possession of all of the facts. So if the responsibility is delegated to an individual employee such as the health and safety representative, it makes good sense to make full use of the knowledge of employees who probably know more about what actually happens on the shop floor or in the laboratory than will the individual representative and the managers. However, if this expertise in whole or in part does not exist in the business, you should seek independent professional advice or contact the HSE.

What are Hazardous Substances?
Under the COSHH regulations hazardous substances are also dangerous substances and are defined (by the Health and Safety Executive) as:  

  • substances or mixtures of substances classified as being dangerous to health under the current Chemicals (Hazard Information and Packing for Supply) (CHIP) Regulations 1994 (as amended; to be replaced in 2002). 

  • substances with occupational exposure limits (OELs). These are listed in the HSE's guidance booklet EH40 - Occupational Exposure Limits, the official list of OELs, revised annually.

  • biological agents (e.g., bacteria and other micro-organisms) if they are directly connected with the work or if exposure is incidental to it, such as farming, sewage treatment or healthcare.

  • any kind of dust in a substantial concentration.

  • any other substance which has comparable hazards to a person's health, but which for technical reasons may not be specifically covered by CHIP. Examples are some pesticides, medicines, cosmetics or intermediates produced in chemical processes.

Many dangerous substances are listed in the HSE publication The Approved Supply List (also part of the CHIP Regulations). These listed substances can be identified by their hazard warning label which must be provided by the supplier of the substance together with a material safety data sheet (MSDS). If a supplier of a substance believes the substance to be dangerous, labeling and an MSDS must also be provided even if the substance is not listed in the HSE's The Approved Supply List. 

What are not Hazardous Substances?
Although COSHH applies to virtually all substances that are deemed to be hazardous to health, the Control of Substances Hazardous to Health (COSHH) Regulations do NOT cover:

  • Asbestos and lead, (these have their own regulations)

  • Substances which are hazardous only because they are:

(a) asphyxiants;
(b) used at high pressures and/or at extreme temperatures;
(c) possess explosive or flammable properties;
(d) radioactive

  • Biological agents if they are not directly connected with the work and they are outside the employer's control. Catching a cold from a colleague would be beyond the employer's control!

Types of Exposure
There are four types of exposure to substances, whether or not they are hazardous. These are:

  • Exposure through inhalation - caused by breathing in a substance in the form of a vapour, dust or aerosol.

  • Exposure through absorption - caused when a substance which is in contact with the skin or eyes or internal surfaces of the mouth passes through the skin.

  • Exposure through ingestion - caused when a substance is swallowed and passes into the stomach.

  • Exposure through injection - caused when a substance enters the body through an open wound.

Effects of Exposure
If an exposure to a hazardous substance is not properly controlled or prevented, it can cause serious illness resulting for the individual in lost income and for the business in reduced productivity and the possibility of expensive prosecution and litigation. In extreme circumstances, uncontrolled exposure can cause the death of an individual and closure of the business. Being aware of the results of uncontrolled exposure might therefore be considered the first step to prevention.

Uncontrolled exposure to hazardous substances can cause, for example:

  • irritation of the skin, dermatitis and cancers

  • asthma and other breathing impairments (e.g., asbestosis) arising from cumulative sensitisation and dusts, asphyxia or poisoning by toxic fumes including smoking-mediated reactions

  • cancers which typically appear years after initial exposure to cancer-causing (carcinogenic) substances

  • poisoning or burning by transferring noxious substances to the mouth by unwashed hands or by consuming from wrongly-labeled bottles (e.g., acids in originally-labeled soft-drinks bottles), overdosing on medicines, and through an open wound

  • infection from bacteria and other micro-organisms

Avoidance of any undesirable effect from uncontrolled exposure to hazardous substances is clearly of paramount importance in the workplace, for both employee and employer alike.

Hazards and Risks
The words hazard and risk have special meanings in the COSHH Regulations and understanding the difference between them is important if the Regulations are to be appropriated correctly. 

Hazard is the potential a hazardous substance has to cause harm. The hazard intrinsic in a substance never changes.

Risk is the likelihood the hazardous substance will cause harm under the conditions of its use. The risk in using a hazardous substance can change and depends on many factors, including:

  • the type of work being done

  • the hazard intrinsic in the substance

  • how the substance is used or misused

  • how exposure to the substance is controlled

  • the type and length of exposure to the substance

  • the presence of other substances which may "enhance" the hazard

With proper control, the risk of injury or development of longer-term ill effects in using hazardous substances should be very small. The same is of course true for non-hazardous substances - water might not be considered hazardous, unless you are a non-swimmer immersed in it! Control is the keyword. 

Scope of the COSHH Regulations
COSHH Regulations cover any hazardous substance which can cause deterioration to your health. These substances can:

  • be used directly in your work, e.g., adhesives, chemical reagents, cleaning materials, paints;

  • be generated because of the work, e.g., dusts or fumes, new substances from reactions including waste products, solvent vapours;

  • occur quite naturally, e.g., pollen and fungal spores in horticulture.

Hazardous substances can be found in just about all types of working environments. Wherever you work, both the substances you use and the environment in which you use them can combine to cause ill health. It is the COSHH Regulations which, when applied, secure a healthy working environment for all.

When do the COSHH Regulations Apply?
The COSHH Regulations are applied in the workplace but to answer this question in more detail, you would need to know:

  • what kind of exposure to a substance will occur when it is handled or used at work and

  • whether the exposure could cause danger to the health of the person handling or using the substance at work.

  • If there is no danger whatever the type of exposure, then COSHH Regulations do not normally apply. For the great majority of substances, these questions have already been considered in deciding whether or not to label a substance as being hazardous. A general rule-of-thumb is:

  • if a substance is NOT labeled hazardous, COSHH Regulations do not apply

  • if a substance is labeled hazardous, COSHH Regulations do apply

For example, there is no warning label on ordinary household washing-up liquid detergent, so if ordinary household washing-up liquid was used at work for the purposes of cleaning, you would not have to apply COSHH Regulations. On the other hand, household bleach does contain a hazard warning label and so if it was used at work, COSHH Regulations would apply.

On and Off Site Working and the COSHH Regulations
Two common situations arise:

  • When your employees work off-site and

  • When contractors (who are not your employees) work on-site.

Employees working Off-Site
In the event that your employees work on other premises not "owned" by you, you still have the responsibility to assess the risks to their health and to ensure a safe working environment. This can only be achieved through the cooperation of those who occupy or own the premises in which your employees will be working. Your responsibilities in applying COSHH to employees who work on other premises is outlined in the HSE's guidance booklet COSHH and peripatetic workers.

Sub-Contractors or other visitors are working On-Site

Although the employer is responsible for ensuring the safety of their people, such as building contractors, working on your premises, you have a share in this responsibility. Again, your responsibilities in applying COSHH to contractors and site visitors who work on your premises is outlined in the HSE's guidance booklet COSHH and peripatetic workers.

An Example COSHH Assessment
The eight steps in a COSHH assessment are discussed in more detail in further pages

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