I'm not the doctor or nurse but I do have a midwife sat right next to me and she says your wife is right.... well sort of. The chemicals excreted through your skin and that are left on your hair, fingers and clothes leave your grandchild at a greater risk of getting all the ususal respiritory problems alone. Secondary smoke is proven to harm babies and toddlers.
I gave up smoking until my baby was 11 months old, I then started again and gave up recently ...AGAIN as my son had a chest infection. They immediately asked me if there were any smokers in the house, I said me, but I never, ever smoke anywhere near anyones children, I would always wash my hands after a fag anyway. They told me that it would still harm my children and no wonder he had a chest infection. Now, she may have been sensationalising but the guilt I felt was incredible. BEst not to have a reason to blame yourself for anything I think.