Do iPods have AVLS ? Keep in mind that different songs have different average and maximum volumes, so if you use a safe volume for one song, that might not be enough for another song. It has to automatically cap the decibels. Asking someone to turn the volume down themselves is insufficient, because with background music, you might only notice it's too loud too late.
Also, it's not as simple as choosing an arbitrary decibel level, like 100 dB, because lower levels can still cause hearing loss, it just depends on the duration of exposure. So, say you drive to work in 30 minutes, than you can listen to louder music than you could while at work for 8 hours.
Here's a list of decibel levels, and safe durations, from the
Mayo Clinic. From reading it, I'd personally like AVLS options of: Off, Safe all day (90 dB), Safe album (100 dB), Child safe (80 dB). Well, maybe with better names, but you get the idea. Also, I chose those decibel levels, but I'd obviously prefer a more informed choice.