User blog comment:Miskos3/Fairy Tail Chapter 486: The Fourth Guest, Review/@comment-7418318-20160525151848

I didn't really think about it befor, but the whole thing how Gajeel is not affected by the MBP is so terribly stupid...

His lungs are made of iron? Then how can he still breathe?

It doesn't matter what his lungs are made out of, as long as they pass air on to the blood, they'll also pass the MBP on. So unless he stopped breathing he should be affected. But if he stopped breathing he is (once again) on a timer until he runs out of air and either suffocates or has to take a gulp of air.