Hello Thank you for your query. Yes, passive smoking and active smoking both adversely affect the growing fetus, particularly during early stages of pregnancy. If you restrict yourself to the non smoking section, you still say that it is less smoky !! I am sure you could plan an alternative trip, however all said and done 4 - 5 hours is not a big deal. Wouldnt it be a better idea to be out in the open instead of a closed, smoky environment at this time ? Make sure she has regular folic acid supplements. take care.