i sew in the finished part of my basement and the only thing it seems to bother is me. i never had any rust or damaged fabrics.
i store my fabric on shelves off the floor and in tubs with cornstarch sprinkled in, more for freshness than anything else. i have three machines and a longarm down there and the only thing i really miss is natural light. in the summer i do run a dehumidifier, sometimes two, but that's new jersey, home of wet air. in the winter i have gas wall heaters, and they work very well. i like being able to do laundry while i sew. that's a big time-saver. i love being separated from everyone's demands on my time.