In some circumstances legislation specifically requires health surveillance before or during work with specified hazardous materials or in specified circumstances. In many other situations the requirement is of a more general nature.
It is often appropriate for pre-employment health surveillance to be used where known risks exist; it could prevent a person sensitive or likely to be sensitive to a hazardous material from coming into contact with the material. It might indicate a need for additional control measures, the need to use particular personal protective equipment or the total unsuitability for the person for the job.
Routine continuing health surveillance is appropriate and required where a substance used or present in the workplace is known to damage health in some particular way, where exposure is likely and where there are valid ways of detect the effect. The surveillance will show whether an employee is becoming sensitive to a material and or whether control measures are operating effectively or have become ineffective. Routine surveillance will identify an issue in its early stages and provide the opportunity to take action before a significant medical condition develops.
Sometimes a medical input is necessary and a doctor or nurse may be required to complete the surveillance; but there are many cases where a supervisor or colleague can complete the task.
See also: Occupational Asthma; Respiratory Sensitisers, Night Work