Quote from @Sergey A. Petrov:
These are tough especially in older buildings. The noxious/ offensive activity likely won’t help. Do you how the smoke gets in? If through an open window / sliding door, the fix is easy. Your tenant can close them when the neighbor is smoking. Use a fan or a portable AC unit if the reason for the open windows is that it is too hot.
Trying to chase all cracks and sealing off your unit in a 1980s building will be mission impossible. Then there are bathroom fans, kitchen fans, laundry ducts, etc. Those can run close to each other and crack overtime allowing smells to travel between the units.
I don’t think the health dept will do anything…
Is this the first communication on the subject from your tenant. If so a long letter (+complaint to the health dept) seems like an overkill. Most will call. But if that is the nature of the relationship your tenant wants to have with you, you are better off with a new tenant
If the tenant has been complaining and you’ve done nothing, that is a different story.
There will always be smells in an older wood frame building. Cooking? That’s another super common one in addition to smoking. Not everyone likes everyone else’s cuisine.
To me it sounds like you’ve done what you can and your might be better off moving to a single family home. If it is not smoke, it’ll be cooking, or noise or something else as different move in and out of your neighboring units
Thanks for your insights. The neighbor smokes insiide and somehow it gets into my unit through the floor / walls / vents etc. I sealed off the shower plumbing access panel which seemed to help but clearly not enough. Other than that I couldnt really pin point any places it was getting in - maybe vents in bathroom but generally seemed pretty pervasiive so yes it does kind of feel like i might be looking at mission impossible for sealiing everythiing off.
This is indeed first communication from tenant. I dont think she filed any complaints or anything but just wanted to understand what her options were before bringing it up with me. If I release her from the lease due to her stated health concerns, i don't see her taking any sort of legal action against me (or having a case), but that's just my speculation. THere are no SF units to rent in this area / price range (greater DC metro) so i'd expect to find tenants maybe more accepting of it if they don't have the symptoms like my current tenant is having, but I also generally don't want my tenants exposed to secondhand smoke :-(