All staff, including part time members, cleaning staff and contractors need to be familiar with the location of fire exits and the fire exit routes. They also need to make sure that all exits and exit routes are kept free from obstruction at all times.
It is illegal to obstruct any emergency route, especially stairways and final exits.
You must also remember that ‘normal’ working corridors are often part of escape routes and even partial obstruction by any objects that prevent the use of the full width of the route is also illegal.