In (8), IA is the number of injuries causing an inability lasting
more than a day, Im is the number of deaths and Eh is the worked
hours. In (9), IGT, IGP, IGM are respectively the off-work days due to
(i) a temporary injury, (ii) to an injury with permanent consequences and (iii) to a death injury, and E is (iv) the total number
of workers employed in the specific work sector. All these data
are, normally, available in the firm’s injury registration book.