ILO Convention No. 161 (1985) concerns the maintenance, by means of a preventive service, of a safe, healthy and well-adapted working environment to promote the physical and mental health of all workers. Occupational health services with essentially preventive and advisory functions shall be developed progressively for all workers, within the framework of a coherent national policy. To this end, the most representative organizations of employers and workers shall be consulted. Occupational health services may be organized as a service for a single undertaking or common to a number of undertakings. They may be organized by the undertakings or groups of undertakings, by public authorities or social security institutions, or by any other competent body. Employers, workers and their representatives cooperate and participate in Their implementation. The task of the services shall be to identify and assess risks from health hazards in the workplace by surveillance of the working environment and working practices, as well as workers health in relation to work. They give advice on the subject and promote the adaptation of work to the worker, as well as on information, training and education in this field; organize first aid, participate in the analysis of occupational accidents and occupational diseases, and contribute to measures of vocational rehabilitation; and carry out their functions in cooperation with the other services in the undertaking and with other bodies concerned with the provision of health services. Their personnel shall enjoy full professional independence and be properly qualified. Occupational health services shall be informed of any known factors and any suspected factors that may affect the workers health, such as occurrences of ill health among workers and absence from work for health reasons, but they shall not be required to verify reasons for absence. The surveillance of workers health in relation to work shall be free of charge and shall take place as far as possible during working hours; it shall involve no loss of earnings for workers. The authority responsible for supervising and advising occupational health services shall be designated by national laws or regulations. See: Occupational safety and health. Occupational segregation See: Job segregation/employment segregation