I signed a lease agreement, and paid the first month's rent on Friday last week. I moved in the following Saturday, and slept there that night. The tenants downstair were smoking pot, and the smoke permeated my apt. on the second floor of the house. I called the lanlord at 8:00 the next morning and said I wanted out of the lease. He is holding me responsible for the full term of the lease. I moved all my stuff out. What should I do?

Maybe try getting your doctor to write an excuse that it is making you ill and tell him you will take it to the magistrate to see what they have to say about the whole situation.

Perhaps move back in, and deal with the people down stairs, calling the police and so on. He will be able to hold you liable for the rent until they re-rent the apartment. So just keep paying the rent until then.