When you list the serious problems facing the restaurant industry, the subject of smoking is right up there with the big ones. Story from owners who have tried a no smoking policy, only to cave-in after numerous complaints from their "smoking" customers. And in all due respect, smokers can be excellent customers, and some people find it impossible to enjoy a drink without a cigarette in their hand (and unfortunately, there are even some people who can't eat without a cigarette in their hand). And it's certainly not easy to ask a customer paying two or three hundred dollars for dinner to stand outside while enjoying a smoke.

In the meantime, we  problem could work through  with so-called "non-smoking areas" where somehow the smoke magically disappears and remains totally confined to that area. And we only permit smoking in the bar areas, and we prohibit pipes and cigars.

The odor that plumbing material may give is generally termed as "waxy plastic citrus," "fruity plastic" and "burning plastic."  Amongst  the various kinds of plactic pipes available, its known that, cPVC has a low odor potential and it doesn't seem to release many organic chemicals. HPDE actually had the highest odor production, although it doesn't release very many organic materials. The PEX-b pipe had a moderate amount of odors and also a moderate amount of organic chemicals that were released into the air. PEX-a had fewer odors and organics release than the PEX-b pipe.  

It would be wise to ask neighbour as to what kind of pipes they use and whether it is giving them any problem or not.