Most likely your blast cabinet has a vacuum/filter? There should be no need to worry about breathing bad things. If you have no vacuum/filter, you should wear a good mask, no matter what you use as media.
My cabinet is used for paint prep - minor rust/paint removal from parts that can fit into my wide cabinet. I remove paint and major rust before blasting. I like this
mixture of alumina and silica from TP Tools. I now mix my own, buying bags locally from an industrial blaster (who blasts my frames and sheet metal at a reasonable cost).
