I would say you are very right to be concerned about this. My youngest son became very ill following a visit to my mums house (pneumonia). He had lung issues anyway, and my mum is a smoker, but she never smoked around the children. I found out after he started getting ill that she was smoking in the living room after we went to bed, so he was waking up a few hours later in a room with smoke on the curtains, carpet, couch, etc. After this I am extremely paranoid about smoke clinging to fabrics, and if I have been socialising with a smoker I will change my clothes before cuddling my kids. I'm not a germ-a-phobe either, we don't go OTT on antibacterial handwash, etc, but on this I feel you can't be too careful as there is plenty of research that shows the effect of passive smoking on health.