Control of substances hazardous to health



The Control of Substances Hazardous to Health Regulations 2002 (COSHH 2002) control the risks from harmful chemicals and other dangerous substances, including biological agents. The regulations apply to:



• chemical substances such as paints, cleaning materials, metals, pesticides and insecticides;



• biological agents such as pathogens or cell cultures;



• carcinogens (cancer-causing substances);



• substances that have been assigned workplace exposure limits (see page 98); and



• dusts.



They cover toxic, harmful, corrosive and irritant and other hazardous substances and prohibit the use of several very dangerous substances for particular purposes (listed in Schedule 2 of the regulations). They do not apply to asbestos or lead, for which there are separate regulations (see pages 112-116 and pages 116-118).



A key requirement under COSHH is the duty to carry out risk assessments (see Chapter 3). Regulation 6 says employers should not carry out work that is liable to expose employees to any substances hazardous to health unless they have made a suitable and sufficient assessment of the risks. All employers must carry out a risk assessment, record any significant findings and review the assessment regularly.



Under the regulations, the risk assessment must consider a specific list of items including the hazardous properties of the substance, information provided in safety data sheets (see pages 108-109) and any workplace exposure limit (WEL). A WEL is the maximum concentration of an airborne substance averaged over a reference period that an employee may inhale. It should not be considered a hard and fast line between safe and unsafe and where exposure cannot be prevented, it must be controlled to as low a level as is reasonably practicable.


Regulation 7 sets out what an employer must do once a potential risk to health has been identified. Employers must ensure that the exposure of workers is either prevented or adequately controlled, by working through a hierarchy of measures.



The emphasis is on prevention. Employers who fail to consider firstly whether exposure can be prevented are in breach of the regulations. The best way to comply with this requirement is to completely eliminate the use or production of substances hazardous to health in the workplace.



The regulations list the control measures to be applied in order of priority, where elimination or substitution is not possible. These are:



• the design and use of appropriate work processes, systems and engineering controls and the provision and use of suitable work equipment and materials;



• the control of exposure at source, including adequate ventilation systems and appropriate organisational measures;



• lastly, and only if adequate control cannot be achieved by other means, the provision of suitable personal protective equipment (PPE).



Regulation 7 imposes an absolute duty on employers to prevent exposure to hazardous substances, as the Court of Appeal’s decision in the following case demonstrates:



The judge in the Naylor case cited the Dugmore case below as crucial in clarifying the regulations:



The Dugmore ruling confirmed that the duty to control exposure is absolute. Employers cannot argue that it is not “reasonably practicable” to introduce control measures. The qualification of “reasonable practicability” refers only to prevention and not to the secondary duty of adequate control.



Employers must ensure that any control measures or PPE are used properly and that employees make full and proper use of any control measures or PPE provided (Regulation 8).



Employers must keep control measures in good working order and repair and ensure that regular tests and examinations of equipment are carried out and appropriate records kept (Regulation 9).



Regulation 10 requires employers to monitor exposure to hazardous substances in particular circumstances. Records must be kept of personal exposures for at least 40 years and in other cases for at least five years.



Health surveillance is required under Regulation 11 where employees have been exposed to one of the substances listed in Schedule 6 of the regulations, or where:



• the exposure of employees is such that an identifiable disease or adverse health effect may be related to the exposure;



• there is a reasonable likelihood that the disease or effect may occur under the particular conditions of the work; and



• there are valid techniques for detecting indications of the disease or the effect.



Health and Safety Executive (HSE) online guidance (see page 46) can be found on its website.



Under Regulation 12, employees must be given sufficient information, instruction and training about the risks involved and the precautions that should be taken. They are also entitled to see the results of environmental monitoring and the collective results of any health surveillance.



Regulation 13 requires employers to deal with accidents, incidents and emergencies. Emergency procedures may be triggered by a serious fire, spillage or flood of corrosive agent liable to make contact with skin; a failure to contain biological or carcinogenic agents; or an acute process failure that could lead to a sudden release of chemicals. There are additional controls set out in the regulations for work with carcinogens (cancer-causing substances) and biological agents.