If I am in a cubicle, what volume of air around me will be cleaned by my Air Purifier?

The total volume that your air purifier can cover corresponds to the square footage indicated in your product documentation..  If your cubicle has an open ceiling and an open entrance with no door, it means that the total surface of the area in which your cubicle is set-up has to be smaller than the square footage capacity of your air purifier, to be the most efficient.  If the area is larger, the machine will still clean the air, but will take a longer time to do so as the entire volume of air contained in the room will have to circulate through the machine.