Children exposed to passive smoking on a daily basis face more than triple the risk of lung cancer in later life compared to youngsters who live in smoke-free environments, research has revealed.

The massive study, involving more than 303,000 non-smokers across Europe, found living in a smoky environment as a child significantly increased the danger of lung cancer in adulthood.

Researchers, writing in the British Medical Journal, found youngsters who experienced passive smoking every day for many hours had over treble the risk of cancer compared to children with smoke-free upbringings.

Children who experienced passive smoking daily but not for many hours faced twice the risk of lung cancer.

Even youngsters exposed to passive smoking just a few times a week were one-and-a-half times more likely to develop lung cancer, according to Professor Paolo Vineis and colleagues from Imperial College London.