I'm pretty sure that voltage is for the electrostatic precipitator.
Air has a resistance of around 10kvolts/cm. Tasers and TIG welders use high voltage to strike arcs across large distances. I'm assuming the electrostatic precipitator used that voltage to increase its range.
High voltage, low current devices generally aren't lethal. You could use that powersupply to build an electric fence. If you can figure out how to bump up the voltage further, you can build yourself a Jacob's Ladder and ecomod like an evil scientist.
- LostCause