Researchers at the University of Cincinnati College of Medicine found children who were exposed to high levels of second-hand smoke and who also developed allergies during early childhood -- around the age of two -- are at greater risk for decreased lung function when they are seven, when compared to children who had not developed allergies.

They also found lung function among girls was six times worse than in boys who were exposed to similar levels of both second-hand smoke.

This was the first study to explore the different effects of second-hand smoke exposure on boys and girls. The study appeared in the journal Pediatric Allergy and Immunology.