Before Occupational Health and Safety laws, most companies paid little attention to the health and safety of their staff. The laws punish companies severely if an employee hurts themselves at work if the company did not do everything they could to make the workplace safe.
OH&S is a responsibility of the HR department. The HR department should have a written OH&S policy that all staff should be told about when they join the company.
If you work with computers, you should rest your eyes and hands for at least five minutes each hour. If you don't, you could damage your eyes and develop a problem called Carpal Tunnel Syndrome in your wrists.
For people who have to lift heavy things, the company should show you how to lift properly so that you don't injure your back. Pay close attention to OH&S policies to protect yourself from serious injury at work.