You don’t say if the working area of the wheels is towards the window or facing into the room.
Towards the window if you are between them, facing inwards if you stand facing the window when you use the grinder.
A bench grinder should not throw particles backwards. The wheels are normally guarded over something like two-thirds of their circumferences, so the particles fly forwards and mainly downwards towards the operator.
You still need eye-protection of course because they can fly upwards; but no debris should go out behind the machine.
So is this grinder properly guarded?