The number of Scots using e-cigarettes has "increased significantly", new research has found.

The 2015 Scottish Health Survey discovered 7% of people were using the devices, up from 5% in 2014.

Levels of "vaping" were highest among younger adults, with 22% to 26% of those aged 16 to 34 having tried e-cigarettes at some point, compared to four per cent to 10% for those aged 65 and above.

The research showed the number of smokers has continued to fall, with just over a fifth (21%) of adults lighting up in 2015 compared to 28% in 2003.

In addition, the average number of cigarettes smoked per day has also dropped, going from 15.3 in 2003 to 12.6 in 2015.

Tobacco smoking is the leading cause of preventable poor health and early deaths across the world, killing around six million people a year.

In Scotland, tobacco use is linked to 10,000 deaths a year - about a fifth of the total.

Meanwhile, the number of children exposed to second-hand tobacco smoke in the home has dropped from 11% in 2014 to 6% in 2015 - meeting the Scottish Government target to reduce it to this level five years early.

Anti-smoking campaigners at ASH Scotland welcomed the fall, with chief executive Sheila Duffy said: "This is a significant drop and good news for the Scottish Government's target of halving children's exposure to second-hand smoke by 2020.

"Tens of thousands more children are now protected from breathing dangerous tobacco smoke in Scotland's homes.

"Efforts like the Take it Right Outside campaign are clearly having an impact and informing people.

"We all need to keep working to minimise children's exposure to tobacco smoke, particularly in their homes.

"The introduction of the law protecting children from smoking in cars later this year will also help to focus attention on the harm that tobacco smoke does."

Public health minister Aileen Campbell said: "It's tremendous news that we've seen such a dramatic reduction in the number of children exposed to second-hand smoke in the home - meeting our target five years ahead of time.

"We launched our Take it Right Outside campaign because we know how harmful these chemicals can be for children's lungs.

"I'd like to thank the many people who have clearly taken the message on board and are now taking their smoking right outside.

"We now need to see further reductions so that even fewer children are exposed."