Despite the bally-hoo over second-hand smoke, there is no good evidence that it poses a measurable risk to bystanders.

ECONOMIST: Land of the smoke-free

There is plenty of evidence that "second-hand" smoke - breathed when you are in the same room as someone smoking - can be harmful, particularly to children, and some parents adopt a strategy of never smoking in their child's presence.

BBC: Warning over 'third-hand smoke'

Martin Dockrell, director of research and policy at the campaign group Action on Smoking and Health (Ash), acknowledges that there is no clear evidence of a significant harm to health from second-hand outdoor tobacco smoke.

BBC: New York's outdoor smoking ban: Will the world follow?