And just like smoking and its second-hand health effects, second-hand fat should be a serious societal concern.

FORBES: Obesity: The New 'Just Say No' For 2013

Previous reports recorded a "sharp decrease" in "non-smokers exposure to second-hand smoke" following the ban in smoking in public places in 2006.

BBC: Scottish Health Survey: Obesity still problem for Scots

Worldwide, as many as 40% of children, 33% of non-smoking men and 35% non-smoking women were exposed to second-hand smoke in 2004, researchers found.

BBC: Passive smoking 'kills 600,000' worldwide

While the ban on smoking in public places in Scotland has reduced the amount of second-hand smoke children are exposed to overall, it has not reduced the number of children being exposed to smoke in cars.

BBC: Stub out car smoke, says charity

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'