STEWARTVILLE, Minn. — Three classrooms at the Stewartville school for special-need pre-kindergarten pupils has been placed off-limits because of elevated mold levels. Superintendent Belinda Selfors said the infestation was not a health risk but was being power-cleaned in an abundance of caution. Professional scrubbers were called to wet-wipe surfaces, to vacuum residual spores, and to scour the air-handling system. The building, whose eight teachers serve 30 pupils. is at 526 Fifth Avenue Southwest, Affected were three of nine rooms.