So you don’t get carbon monoxide poisoning from running the vehicle in an enclosed bay. They hook that up to the exhaust of the vehicle and blow it outside.

Looks like an exhaust system- the hose sits on the engine exhaust pipe and the blower on the ceiling vents the fumes out to the roof.

Looks like an air exhaust. You can see the blower on the left. And then it connects to the top of the roof. To exhaust. It might run in reverse pulling fresh air in. Not sure. But as you can see in the photo other examples of this tube being pulled down to the work area. So if you’re working on an engine you don’t want to asphyxiate your workers you would need to exhaust the exhaust