Don't worry about "bringing home" mold spores. They are there and always have been, unless it is some rare, imported variety. If work clothes are covered with it, he should change before coming home, put the dirty stuff in a plastic bag, launder it alone with bleach in the wash water. Mold grows in dark, damp conditions. Get rid of the dark and damp first. Clean with bleach - doesn't need to be full strength. Kilz is a primer, not a cure-all. The label says....clean, dust free, remove grease and mold, etc, etc. If bleach is not an "alternative" (why not?), then mold is the alternative. Mold will eventually eat into paint, wood, etc.