A new study suggest parents who expose their children to second hand smoke are shortening their lives.
Researchers in the European Heart journal say "passive smoking," among other things, damages children's arteries and increases their chances of having a heart attack or stroke when they get older.
Study author Dr. Seana Gall told the Australian Broadcasting Corporation that "parental smoking in itself was causing damage to the arteries."
The damage she said is "direct" and "irreversible." told the author Dr Seana Gall, from the University of Tasmania, said: "Our study shows that exposure to passive smoke in childhood causes a direct and irreversible damage to the structure of the arteries.
According to experts, there is no safe level of second hand smoke exposure.