Boys who inhale second-hand tobacco smoke at home may experience significant levels of raised blood pressure, a study has found.

But in girls, passive smoking appeared to be associated with a lowering of blood pressure. The research from the University of Minnesota, involving more than 6,400 young people, is the first to assess the effects of passive smoking on blood pressure in children.

"These findings support studies suggesting that something about female gender may provide protection from harmful vascular change," said Dr Jill Baumgartner. The findings were presented yesterday at the Pediatric Academic Societies' meeting in Denver, Colorado.