Health surveillance aims to provide early identification of potential ill health as a result of worker’s exposure to:

• • Hazardous substances such as asbestos or lead
• • Certain biological agents such as hepatitis B or C
• • Physical hazards such as noise, vibration or ionising radiation.

Senior managers then need to analyse the data to help them implement better controls to prevent the development or exacerbation of pre-existing conditions. For example, if workers are often exposed to noise levels above the daily or weekly upper action level of 85dB(A) and health surveillance data as measured via hearing tests indicates that worker’s hearing is gradually being negatively affected, then managers know that their current control .