Dry film as mikeseb says.
Take the film in your hands, put it above a black/dark desk, stick a lamp over it and start taking off the dust specks with a brush.
When you are finished with one side, turn it and start with the other side.
With time you will notice that you need to turn the film at a specific angle to see the dust.
Scanning film is not an activity for people in a hurry.
PS before you try spraying canned air on film, turn on a sound recorder, then once finished, hear yourself pronounce horrible cusswords at more than 100 decibels over the film flying from your hands into a pool of oil & dust.