It is important to understand what causes problems at work, what gives rise to the issue or, as in this case, what are the activity hazards. If you cannot understand what causes the hazard, how could you hope to fix it?
Activity Hazard 1
You might use fork lift trucks, the type with solid rubber tyres and no suspension. You might use these trucks in the yard, where there are rain gullies and pot holes. These might lead to vibration issues. So far I have described the equipment and a location, which might suggest that it is either an equipment hazard or a location hazard. If what you describe is how operators drive the fork lift trucks for prolonged periods, without frequent breaks, then what you are describing is an activity hazard.
Activity Hazard 2
Some other activity hazards that you might encounter in a warehouse relate to manual handling. If people need to overstretch or stoop to lift or lower items, then these people would be exposed to an activity hazard. If, let’s say when you are unloading, you get people to form a line and pass off the items being unloaded, this may lead to people twisting repetitively, another activity hazard.
Activity Hazard 3
Maybe you use a stretch wrapping machine. Perhaps your warehouse processes so much product that there is a constant need for palletised materials to be stretch wrapped. The stretch wrap reel might be mounted quite low down, giving rise to the need for the operator to bend down in order to start the process off. If that operator was bending down repetitively, perhaps for the greatest part of his 8 hour shift, then this would give rise to an activity hazard.
Like most workplaces there are many potential activity hazards in warehouses. Some of these same hazards are present in other workplaces too. If the problem arises due to the way that you do things, for long periods, repetitively and without breaks, then you may well have an activity hazard.
Good luck with your project.