PASSIVE smoking is a huge threat to the physical and mental health of Scots, new research has revealed.

Exactly eight years after the nation's historic March 2006 public tobacco ban, non-smokers are still paying the price of those who light up in their homes.

A detailed analysis of surveys of thousands of Scottish households found increased risk of stroke and heart attacks and overall mental health problems among non-smoking adults who share a home with a smoker.

The ban on smoking in public places, such as bars and officers, has already been credited with helping Scotland cuts its historically high levels of mortality from cardio-vascular disease.

However, researcher Ivy Shiue of Heriot-Watt University in Edinburgh found that those exposed to passive smoking at home - and in other places - had a dangerous combined impact on their health.Writing in the Journal of Environmental Research and Public Health, Ms Shiue said: "It was observed that being exposed to indoor passive smoking, in particular in more than two places of exposure, was significantly associated with risks of stroke, angina, heart attack, abnormal heart rhythms.

"The cumulative risks also impacted on sleep problems, self-recognition, making decisions, self-confidence, under strain constantly, depressed, happiness and self-worth. The significance remained for sleep problems, self-confidence, under strain constantly, depressed, and happiness in never-smokers.

"Elimination of indoor passive smoking from different sources should still be a focus in future public health programs."

Ms Shiue called for further "restrictions" on indoor smoking but stopped short of calling for a ban, which would be hard to police.

She said: "This is something public health campaigns should target."

Sheila Duffy, chief executive of anit-smoking lobby Ash Scotland, agreed: "We know from our research most parents who smoke take some steps to protect their children but don't know as much as they could about the risks and how smoke behaves.

"The only way to protect people is to make homes smoke-free and ensure smokers go right outside to light up. Government can support people to do that by highlighting the practical steps they can take."

MPs last month backed a ­smoking ban in cars carrying children.