"We are not 100% sure so we protect the adult while letting the child take the risks. Is that logical ?"
Are you stating agreement with those of us that stand against the "smoke free workplace" legislation? OR are you making a case for the government to monitor behavior in one's home, "for the children"?
I think that if smokers really cared about anyone but themselves, these would not be issues. Instead everyone is asked to assume risks just so smokers won;t feel withdrawal symptoms.