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Control of dangerous substances

The above regulations came in to force on 6 April 2005 and they focus on good practice that will help employers' protect their employees' health from being harmed by chemicals or hazardous substances that are used in the workplace.

Eight new principles of good practice have been introduced by the regulations which will apply regardless of whether a substance has an Occupational Exposure Standard (OES) or Maximum Exposure Limit (MEL).

A simpler exposure limit is also being introduced so that Workplace Exposure Limits' (WELs') now replace Occupational Exposure Standards' (OESs') and Maximum Exposure Limits' (MELs').

As of 6 April 2005 employers are now required to:

  • Apply the eight principles of good practice to control substances hazardous to health;
  • Ensure that the WEL is not exceeded; and
  • Ensure that exposure to substances which can cause occupational asthma, cancer or damage to genes that can be passed on from one generation to another are reduced as low as is reasonably practicable.

Principles of good practice

  • Design and operate processes and activities to minimise emission, release and spread of substances hazardous to health.
  • Take into account all relevant routes of exposure- inhalation, skin absorption and ingestion- when developing control measures.
  • Control exposure by measures that are proportionate to the health risk.
  • Choose the most effective and reliable control options which minimise the escape and spread of substances hazardous to health.
  • Where adequate control of exposure cannot be achieved by other means, provide, in combination with other control measures, suitable personal protective equipment.
  • Check and review regularly all elements of control measures for their continuing effectiveness.
  • Inform and train all employees on the hazards and risks from the substances with which they work and the use of control measures developed to minimise the risks.
  • Ensure that the introduction of control measures does not increase the overall risk to health and safety.

What do I need to do now?

You can continue using safety data sheets that refer to the old limits until their supply is exhausted and news ones are produced. Also COSHH Assessments can be updates as part of employers' periodic reviews.

Employers who already comply with COSHH will still be able to do so by continuing to apply the principles of good practice.

Further information and advice on good practice can be found on the Health and Safety Executive's (HSE) web site at and on the HSE's COSHH Essentials web site at

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