Corrosive acids deals 1d6 points of damage per round of exposure, except in the case of total immersion (such as in a vat of acid), which deals 10d6 points of damage per round. An attack with acid, such as from a hurled vial or a monster’s spittle, counts as a round of exposure.
The fumes from most acids are inhaled poisons. Those who are adjacent to a large body of acid must make a DC 13 Fortitude save or take 1 point of Constitution damage each round. This poison does not have a frequency, so a creature is safe as soon as it moves away from the acid.
Creatures immune to acid’s caustic properties might still drown in it if they are totally immersed (see Drowning).