I hate IPods! They are small, convenient, give good sound, hold lots of music, and are very affordable. So why do I hate them? Because when you put both ear pieces in your ears they block out the entire world. Completely! So you never know what is going on around you. You could walk into a turning car, blunder into a dog fight, or almost anything.
So if you must use them, leave 1 ear uncovered so you can hear what is going on around you, what is coming up behind you, what you need to know to avoid dangers.