User blog comment:Miskos3/Fairy Tail Chapter 486: The Fourth Guest, Review/@comment-7418318-20160525151848/@comment-5303512-20160528063755

Quick question, how can iron be poisoned? That logic is absolutely absurd to the max. It's like saying machines are able to get sick from organic diseases. You can't poisons something that can't be poisoned. Besides I have already explained my peace which is making his iron lungs operating as air filters which is the removal of dust, pollen, mould and bacteria from the air including other airborne contaminants such as organic volatile compounds and ozones.

And by your logic, if solids don't work, then gas masks should be useless as well because it is made of solid material as well. And if you say the do work because it is their purpose then Iron Lungs work as well when Gajeel constructed them to do just that.

Water won't work because MBP is not liquid, it's particulates, if Wendy's sky magic effects MBP then they wouldn't have been in the mess during Tartaros, Natsu's flames would have hurt Keith but didn't.