By law, every restaurant above certain limit of customers, is obligated to have a non-smoking section.
It is a matter of physics however
Smoke has the annoying property of filling the surrounding space.
I really really detest smoke and I pray for the day it becomes banned from restaurants, but in the meantime, if you ask for the non-smokers area (which most restaurants have) you will have a good chance of avoiding our behated friend
As for clubs/discos/pubs... forget it. You will end as smoked as a barbaque steak no matter where you go. Try to go to modern and ample discos, where air recycling systems will lessen the problem a bit.
Fernando