There are three (3) main reasons that have been generally accepted as why moves to improve occupational safety. As the name suggests, it is the idea that the workplace is as safe as possible for those who work in it. This means that a great deal of inspection is imposed upon every aspect of the workplace because danger can come from a wide variety of things.
The first reason that occupational health and safety has been taken up with such vigor, is moral. It is the idea that no one should to risk their health for the sake of work, and that any risks at work can be reduced or eradicated altogether . In the past, some workplaces were particularly dangerous, especially in factories. In extreme cases, people have even lost limbs in accidents.
The second reason is economic. If someone is injured at work, then it can cost the whole of society a great deal of money. Primarily, it can cost the taxpayer a lot of money because of medical costs associated with any injury. There is also a significant cost to the employer too, who might need to pay sick pay. They will also have a potentially valuable worker missing for a long time, or possibly forever. Economics is quite clearly a big reason for the importance of occupational health and safety.
The third reason is legal. Firms are legally required to invest in occupational health and safety in order that they never face legal proceedings resulting from an injury in the workplace. If they take precautions to prevent any injuries, then the likelihood of them being prosecuted is greatly reduced.