I think you need to worry more about spark producing equipment (open brush type motors, ferrous metal blades contacting ferrous metal housings, etc.) than static electricity. Normally humidity has to be real low to produce static sparks. Your fan equipment should be rated spark proof and the motor should be fully enclosed (TEFC - Totally Enclosed Fan Cooled) at a minimum. As far as discharging the vent, vertically would be the best. Get it up where the breeze will dissipate it.
