Workers' compensation is a law that covers essentially any injury or disease process that occurs during the course and scope of one's employment. It can be an obvious injury where one is carrying a box, trips, falls and fractures an ankle, or it can be a not so obvious injury where we have someone who does repetitive activities and develops what we call repetitive trauma injury such as carpal tunnel syndrome. It could also be a disease process where a worker is exposed to hazardous chemicals and develops a cancer, for example. It can also be a lung disorder where a worker is exposed to dust or fumes which causes a lung disease.
There are many different types of injuries that workers' compensation encompasses and if you have any questions about that, I suggest that you call a competent attorney such as the ones here at O'Malley & Langan.