Passive smoking may be more dangerous for teenage girls than boys, a new study suggests.

Passive (second-hand) smoking is already known to cause heart and lung diseases, including lung cancer. Australian scientists decided to investigate whether exposure was different for teenagers depending on their gender.

They looked at over 1,000 teenagers and found that girls exposed to passive smoking had a bigger risk of developing heart disease compared to boys who were also exposed.

They found that girls had less HDL cholesterol in their bodies - this is considered ‘good' cholesterol as it reduces the risk of heart disease. However the HDL cholesterol levels of boys exposed to passive smoking did not appear to be affected.

"In our study we found that 17-year-old girls raised in households where passive smoking occurred were more likely to experience declines in HDL cholesterol levels. Second-hand smoke did not have the same impact on teenage boys of the same age, which suggests passive smoking exposure may be more harmful to girls," the scientists from the University of Western Australia said.

They described the finding as one of ‘serious concern', given that heart disease is the biggest killer of women in the Western world.

They called for more focus on attempts to reduce exposure to passive smoking in the home, particularly among girls.

Details of these findings are published in the Journal of Clinical Endocrinology & Metabolism.

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