New research has shown the harmful chemicals in second-hand smoke linger and travel for up to five hours after the visible smoke has disappeared.

The advice being issued now is that because 85 per cent of second-hand smoke is invisible and odourless, many are unaware that smoking indoors, even at an open window or standing at the back door, isn’t enough to protect children.

Dr Linda de Caestecker, NHS Greater Glasgow and Clyde’s director of Public Health, said: “We fully support this campaign which aims to give every child in Scotland the opportunity to grow up in a smoke-free environment.” For help and advice on how to take smoking right outside, visit www.rightoutside.org.