Scientists from University College London (UCL) found that passive smokers are exposed to smoke as much as 50 percent more likely affected by psychological distress, than those not exposed to smoke.

As a result, residents of a mental hospital for passive smokers, increased almost threefold during the last six years. As for smokers who were treated in a mental hospital increased nearly four-fold.

Doctor Hamer and colleagues from UCL examined 5560 adults who do not smoke, and 2595 adult smokers, who do not have a history of mental illness. The study answered questions about psychological distress and those who were treated in a mental hospital that has been tracked for six years.[source:hidayatullah.com]