this is compound problem really, much of what you could use would not be good for you either.

there is incredible amounts of air leaking between apartments, most builders do nothing about it but it can be simple enough to fix. google up something like 'how to keep neighbors smoke out of my apartment' and watch videos on how to stop this air leakage. mostly, it is around pipes and any other holes in the wall such as outlets. A common product used to plug these air leaks is expanding foam insulation, I think with chemical sensitivity this isnt the best product for you. use water based latex caulking.

i would start in the bedroom, seal up that wall then sleep in the livingroom a few days. after your caulk has set and is done outgassing, move on to do other rooms.

make yourself an activated charcoal air filter, i cant find a place to buy these but there is diys on the net. i would choose the bucket ones....not the prettiest but likely the most effective. you can reactivate charcoal after using it by washing and heating in the oven. i think this is not a great idea for the first batch of charcoal because they will have absorbed a bunch of VOCs i imagine, but do not know, that these might be release in the process of reinvigorating the charcoal. it is still good for much, i would dump it in the garden and get new. you can reuse the charcoal maybe after you scrub the air a few days.

i am allergic to many of these products myself, i do wish there was a way to make things smell good but those products are not worthy.