If they continue smoking, you'll have to put up with it until their lease is over.In the future, make it clear that smoking of any substance is forbidden inside any structure, including garages, storage sheds, etc.

Keep in mind that when wanting to do this with a mortgage banks first want to see substance and at least one yearly balance statement.

Despite paying a substantial fee, I found that beyond basic instructional videos and repetitive weekly calls, there was little substance to aid my learning.

It was discussed in one of the lender earning call but I still can't get the substance how they able to change the books. 

Tenant shall not allow any sweepings, rubbish, sand, rags, ashes, bones, grease, or other substances to be thrown or deposited therein.

Amazing how many investors, who are supposed to be business people, not just normal consumers, fall for sales pitches that lack substance once you dig deeper.

Quote from @Samuel Mutschler: This is mental illness, substance abuse, or someone trying to get out of their lease.I would tell them the rental is unsafe and they should leave.

this is in our lease regarding prohibited conduct, aka violation of the lease, "criminal conduct, regardless of whether or where arrest or conviction occurs, including but not limited to: manufacturing, delivering, or possessing a controlled substance or drug paraphernalia; engaging in or threatening violence; possessing a weapon prohibited by law; discharging a firearm in the apartment community; or, except when allowed by law, displaying or possessing a gun, knife, or other weapon in the common area, or in a way that may alarm others"I'm no lawyer but the person who wrote this lease is a lawyer, "regardless of whether or where arrest or conviction occurs" leads me to believe that suspicion of illegal activity is enough.

Information is readily available, and I understand it can be difficult at times to discern the trash, the selling from the substance.

First off, I want to thank each of you for taking the time to nourish me with wisdom!