There are two views to this question.
The first is that if a person is a heavy smoker i.e. your doctor they normally have a very offensive smell about their breath.From the experiences I have had around doctors and there have been a lot, they have either not smoked at all or smoked very little as I could not detect it on their breath.
If I did detect this odour and it was offensive and they had a nasty smoker's cough to go with it, if this was a GP, yes I would feel very uncomfortable being in their presence. Some people who are prone to asthma and other types of respiratory problems, such as myself, would be at risk being under the care of a doctor who smoked.
The other view is that the doctors themselves know the risk more than the patients they are treating and it is a very bad example to their patients. For example a patient might be wanting to give up smoking, and the doctor they are being treated by is a smoker. This would definitely not be sending that patient the right message.They would be saying it is fine to smoke, go ahead. We all know I hope, that this is far from the truth.
Therefore, if someone is trying to give up, stay away from a doctor that is a smoker, it certainly won't help. On the other hand, if they smoked heavily and had a nasty breath and cough, this could be an excellent incentive to give up smoking.
because it can also lead to cancer, and no one wants to live like that. do they.