I have heard some stories about hams getting their feet caught in ventilation holes, but those are very rare. If a hamster suffocates inside a ball... Then the owner probably wasnt supervising him and didn't see the signs. I let mine go in balls but that's only because they are in temporary cages with very little space. I've built a large playpen out of cardboard boxes and tubes and scattered food and toys in it, and my ham Lilo seems to enjoy that more than a ball. She still gets bored in the playpen, but at that point I let her run on my bed. Really its between you and your ham
