“This is because control measures may not always be reliable, despite appropriate checking, training and maintenance,” it adds. “Health risks which require surveillance include noise, vibration and substances hazardous to health.” Surveillance is used to identify occupational diseases, such as chronic obstructive pulmonary disease; occupational asthma; dermatitis; and silicosis. The law also requires that health surveillance includes medical surveillance for certain hazards such as asbestos, lead, and ionising radiation (see Chapters 6 and 7 for more information).