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Materials and Substances Hazardous to Health

Hazard Related Topics

Substances Hazardous to Health

The designer of any structure has a duty to examine the substances to be used and, after identifying those which are hazardous, attempt to replace them with a less hazardous alternative. Where there is no alternative then the Control of Substances Hazardous to Health Regulations makes it a legal duty for those responsible to carry out an assessment to identify, assess and prevent or control risks to health.


The manufacturers or suppliers of any substance delivered for use have a legal duty to provide information about the substance under the Chemicals (Hazard Information and Packaging for Supply) Regulations. The label on the substance or the safety data sheet supplied should be read to identify the hazards. Other substances may be present on site naturally or may have been left by other previous uses of the site. Examples are sewer gases or the substances left in contaminated land. Information about these may be gathered by the client or the design team.


This should look at the way people are exposed to hazardous substances and whether it will harm anyone's health. Harm could be caused by:

  • Breathing in fumes, vapours or dust. It may be that the manufacturer's information warns of the risks of inhaling the substance. If so then the method of using the substance may need to be examined. Is the substance to be used in large quantities? Will the atmosphere be heavily contaminated e.g. by spray application? Will the work take place in a poorly ventilated area? e.g. a basement.
  • Direct contact with skin or eyes. The manufacturer's information may warn that direct contact with the substance is harmful. Will the method of work make skin contact likely, e.g. from splashes or spillage? What is the strength of the substance, e.g. is it strong acid or alkali?

There are basically two kinds of risk with these substances. Immediate risks e.g. being overcome by fumes in a confined space, and long term risks e.g. materials like cement can cause dermatitis or such substances as isocyanates are sensitising agents and can cause people to have violent reactions even though they have used the substance many times before.


The best method of prevention is not to use the substance at all. This can be done by either specifying that the job be done in a different way or by specifying a different but less harmful substance e.g. specifying a water based paint instead of a spirit based one.


If there proves to be no alternative to the substance then ways must be found to avoid exposure.

Examples of such control measures include:

  • Ensuring good ventilation in the work area if necessary by using mechanical ventilation equipment.
  • Using as little of the substance as possible.
  • Fit exhaust ventilation, ensuring that the extracted fumes are led away to places where they could not affect other people.
  • Use water suppression to cutting and grinding tools.
  • Apply solvent based substances by using a brush instead of spraying.

If adequate control cannot be achieved by using any or all of the above means then personal protective equipment such as respirators, suitable eye protection and protective clothing should be used. These means should only be used as a last resort.

Personal Hygiene

Substances can be a hazard to health when they are transferred from the hands onto food, cigarettes etc and so into the body. It is, therefore, important that good hygiene facilities are provided on every site and also that construction staff are trained that it is vital that the hands are washed before eating, drinking, smoking and using the toilet.

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