The way to avoid that would be to have a filter or receptor in line before the vacuum
pump. On many vacuum pumps you'll see a small glass jar on the intake side with a
filter inside. Vacuum is drawn through this jar and any debris gets trapped in the jar
so it does not contaminate the pump. There will often times be a second filter on the
exhaust side, sometimes referred to as a muffler, to contain anything from being
ejected into the atmosphere that shouldn't. Components used have to be able to
withstand full vacuum (29" Hg) for sustained periods.