Soon they are out of the airborne poison as the dust starts to settle. He doesn't hear the skittering behind him any longer so he hopes that the poison did its job. It is hard to say considering he doesn't know the physical makeup of whatever was going to attack them but it was worth a shot as at least a distraction.

As he reaches a wider part of the cave he slows down and finally stops. Setting her down when he is sure they are safe. The wider area means more air and more places for the poison to dissipate around them. But it was just a small poison bomb so he knows it won't reach them.