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Control of Substances Hazardous to Health (COSHH)

The Control of Substances Hazardous to Health (CoSHH) Regulations is legislation that requires the management of risks associated with substances in use or otherwise affecting the workplace if they are deemed to be ‘hazardous to health’.

Watch the video for a quick introduction to CoSHH.

Routes of exposure

Hazardous substances can take many forms and include:

  • chemicals
  • products containing chemicals
  • fumes
  • dusts
  • vapours
  • mists
  • nanotechnology
  • gases
  • biological agents (i.e., germs)

There are five main ‘routes of exposure’ to hazardous substances. Click on the ?’s to learn more.

Principles of control

The CoSHH Regulations define the principles of good control practice for hazardous substances.

Delivery of chemicals

Click on the ?’s for more information about safe delivery of chemicals.

Storage of chemicals

How NOT to do it…

Different types of chemicals should be effectively segregated in storage and use. This is particularly important where different disinfectants, or acids and disinfectants, may come into contact with each other and produce chlorine gas, fire or an explosion.

Each liquid chemical, whether in tanks or drums, should be in a separate bund; each bund should be capable of holding 110% of the chemical stored. Bunds must allow for puncture of the drums or tanks. Bunded areas should be clearly marked, giving details of the contents.

Safety data sheets (SDS)

A SDS will contain the information necessary to allow employers to do a risk assessment as required by the Control of Substances Hazardous to Health Regulations (COSHH). The SDS itself is not an assessment. However, it will describe the hazards helping employers assess the probability of those hazards arising in the workplace.

Example SDS for calcium hypochlorite.

In emergency scenarios, it’s likely that the casualty will need to go to hospital for further treatment. The medical staff will need to know more about the particular chemical that the casualty has been in contact with, so the relevant Safety Data Sheet must accompany the casualty to the hospital.

Handling Chemicals and Personal Protective Equipment (PPE)

The Personal Protective Equipment Regulations 1992 require pool operators to assess and provide necessary personal protective equipment (PPE) when performing certain tasks. It is recommended that pool operators take the advice of suppliers of equipment and chemicals as to what PPE is needed. The Safety Data Sheet will help determine the exposure controls/personal protection required. Using the example SDS for calcium hypochlorite, section 8 provides the following information:

Wear tight-fitting, chemical splash goggles or face shield.

If ventilation is inadequate, suitable respiratory protection must be worn. Wear a respirator fitted with the following cartridge: Particulate filter, type P2.

Use protective gloves. The most suitable glove should be chosen in consultation with the glove supplier/manufacturer, who can provide information about the breakthrough time of the glove material. Neoprene gloves are recommended.

Provide adequate ventilation. Avoid inhalation of dust. Observe any occupational exposure limits for the product or ingredients.

Provide eyewash station and safety shower. Wash hands at the end of each work shift and before eating, smoking and using the toilet. Change work clothing daily before leaving
workplace. When using do not eat, drink or smoke.


Employees who have to work with the chemicals should have respirators on personal issue (no sharing). The type of respirator, training, instructions and maintenance arrangements should be determined as part of the CoSHH assessments.

Where chlorine gas or liquid bromine are used, or there is any risk of generating chlorine or bromine gas by accidental mixing of chemicals, it is important to provide precautions against exposure to toxic gases. Sufficient canister respirators should be kept available in or near plant rooms. Canister respirators should be located in the immediate area where the leak may occur and also at the entrance door to these areas where they can be used by staff who may have to go into the area where a leak is apparent.

Canister respirators can only deal with low concentrations of toxic gases. Pool operators need to consider suitable emergency procedures for more serious leaks, where appropriate in consultation with the fire authorities. Canister respirators should only be used as a last resort. Where they are used, it is important that attention be paid to the manufacturer’s instructions, in particular the limitations of the product, and that canisters are replaced shortly after the seal has been broken.

Chemical incidents

For spillages of chemicals, the Pool Water Treatment Advisory Group (PWTAG) provide the following procedures:

In any emergency a quick but calm reaction is necessary. Personnel and the public must be protected. Only personnel that know the product and have been trained to handle spills should be allowed in the area. Appropriate protective equipment should be worn when dealing with a spill.

Whatever the cause, the approach to any spill is to:

  • follow the emergency action plan
  • protect the public
  • protect staff
  • contain the spill
  • stop the leak
  • clean up the spill
  • protect the environment