Smoking is a 'current issue' that is never given the proper status of a 'current issue'. Smoking is dangerous. And if this were genuinely understood, then surely 'common sense' would drive people to stop. But I do not intend for this to be another lecture on the dangers of smoking, primarily because such remonstration doesn't work. We must take a more active, combative approach to make smokers appreciate the harm they are causing to us and, equally importantly, to themselves.
Cigarettes are nasty, evil little things.
They are addictive. The helplessly agitated, ratty smoker will go to extraordinary lengths in order to get a cigarette in to their system. This question is loaded. This person wants to smoke and they want to do it there and then. If you respond with anything but 'no, go ahead' then you are giving the wrong answer and that is why you comply.