I get a sewage smell from bathroom sink when gas fire logs, the vented type, in fireplace are lite in the living room. Bathroom is on same floor.

Thanks

I am not sure how the gas logs would effect the sink but what I do when my sink gets smelly is put about half a cup baking soda in it then dump some vinegar on top of it then after a minute or two pour a pot of boiling water -I especially do the boiling water if it is backing up too.