In a sheet separating apparatus, for example an automated teller machine (ATM) in which banknotes are removed one by one from a stack (12) of banknotes, includes a vacuum pump (32), and suction means (10A,B,C,D) connectible alternately between a vacuum enable port (30) of the vacuum pump (32) when a note is picked from the stack (12), and a vacuum release port (42) of the pump (32), when the note is released from the suction means. Pre-filtered air from the vacuum pump (32) is therefore partially recycled, and dust is substantially excluded from the system.