Ratchet & Clank Tips

Invincibility on Rilgar
Complete only the first half of Blackwater City (ie don't do the hoverboard race.)
Return after you have acquired the O2 mask from Pokitaru.
Equip the O2 mask from your gadgets menu,
and you cannot be harmed by the exterminators or tanks spraying the green fog.!

(Note Green Slugs and giant fish can still bite you!)