Eh Zulen, you should take a note: time flows slower in anime world.
Which now that old favorite discussion of "How long have the Straw Hats traveled, fought, etc." will be brought back up from the ashes.
Yeah, ok I'm going to state my true opinion here, the bomb should of killed Pell. The fact is that the bomb did not kill him though.
Just stop revisiting about the whole issue since Pell was a minor character that was post to represent something for Vivi. If you let this whole issue take over your life, well you need a new hobby besides anime watching and manga reading.