38 181. Presidential decrees 17/1996 and 159/19991 on measures to improve employees' health and safety at work transpose directives 89/391/EEC and 91/383/EC. These place a number of obligations on employers, including general requirements regarding prevention, information on occupational risks and the application of all health and safety measures, and specific ones concerning written assessments of occupational risks and a special register and list of occupational accidents. Section 4§1 of PD 17/1996 requires every undertaking, irrespective of number of employees, to appoint a safety technician to its staff and those with more than fifty employees to employ an occupational physician. Paragraph 4 authorises employers to delegate safety or occupational health responsibilities to one or more members of their staff, subject to minimum time requirements (paragraph 7) to ensure that the individual(s) concerned have sufficient time to carry out all their responsibilities to the letter. 182. Section 7 of decree 17/1996 imposes several general obligations on employers, covering occupational risk prevention, regular information to employees, and the establishment of appropriate health and safety machinery, with the attendant obligation to make available the necessary facilities. The general principles that must be applied include risk avoidance (prevention, assessment and elimination), peoplecentred organisation of work and maximum use of technology. Moreover, when several employers share the same work places, they must co-operate on health and safety matters, co-ordinate any measures introduced and inform each other of any risks (paragraph 9). 183. All employers must produce written assessments of occupational risks, including, under section 3 of PD 159/1999, detailed information on risk characteristics, related preventive measures and the physical, biological or chemical risks to which employees might be exposed. In carrying out such assessments, the occupational physicians and safety technicians concerned must make quantitative and qualitative assessments of the occupational risks and take account of the results of regular health checks. 184. Under section 10, employees must be consulted on and participate in the formulation of health and safety policies. Section 11 requires employees to be informed of the relevant legislation, the risks identified and relevant measures taken. 185. The Presidential decree (PD) 294/88 on minimum safety technician and occupational health coverage in relation to number of employees and the degree of risk of the activities concerned, which implements Act 1568/85, divides undertakings into three categories according to risk: A = high risk activities, B = medium risk activities, C = office work. For each category, there is a minimum annual requirement for safety technician and occupational health coverage, which itself varies according to number of employees. 1 Official Journal A 11 (18/01/1996), as amended by presidential decree 159/1999, Official Journal A 157 (03/08/1999).