Question

Why does Montressor warn Fortunado about the air in the vaults

Answer 1

Answer:

The purpose that Montresor had in telling Fortunato about the air in the vaults was to give him a false sense of security as they went deeper. Montresor wanted Fortunato to believe that he had his "friend's" best interest at heart so that when he ensnared him in the trap and began to bury him alive he would be completely stunned by the act.

Hopes this helps :)