Smoking neighbor next door to my tenant

[Lily Daudert]

I have a tenant in my Chicago condo.  The next door neighbor, who is also a renter but different landlord, shares a common entrance to their respective units.  The neighbor smokes, incessantly.  The smoke wafts into the hallway which also is open to the  and into my tenant's unit.  She has tried to make a friendly effort to speak to the neighbor but he's been described as 'a dud that doesn't really go anywhere but work' but she's trying to be cordial with him.  Months ago, I've asked the condo association management to also suggest to his landlord about getting a $15 draft blocker for his door.  My tenant can still see through underneath his door.   

She's a wonderful tenant and would hate to lose her over a smoking issue.  She hasn't indicated that she would move after her lease but that is always her option to do so.  

Any suggestions on this matter?  

thanks in advance!