Second-hand smoke exposure in Scotland is down 96% since the country’s landmark smoke-free legislation came into force on March 26, 2006, new research by the University of Stirling and Public Health Scotland has shown.
However, analysis also shows that many workers remain exposed to second-hand smoke in settings not fully covered by legislation, such as private homes visited by care workers and outdoor hospitality.
The study led by Professor Sean Semple, of the University of Stirling’s Institute for Social Marketing and Health (ISMH), analysed data across 26 years (1998–2024) from the Scottish Health Survey, examining salivary cotinine, a biomarker that measures recent tobacco smoke exposure in non-smoking adults.
The research paper Twenty years on from smoke-free legislation in Scotland: a secondary analysis of the Scottish Health Survey dataset (1998-2024) examining changes in household smoking rules, and salivary cotinine concentrations among non-smokers was published in the journal Tobacco Induced Diseases.
The research shows there was a 95.7% reduction in average salivary cotinine levels among non-smokers between 1998 and 2024, with the most rapid decline occurring in the years immediately after Scotland’s smoke-free legislation came into force.
However, since 2011, improvements have slowed – in 2024 almost a quarter of non-smoking adults still had measurable levels of cotinine, indicating ongoing exposure to second-hand tobacco smoke on any given day.
Professor Semple said: “Scotland’s smoke-free legislation has delivered extraordinary public health gains. The scale of the reduction in second-hand smoke exposure since 2006 is remarkable and shows how effective bold legislation can be.
“Scotland should be immensely proud of this achievement, and we should celebrate our success in clearing the air and improving health for the millions of people who previously had to breathe second-hand smoke at work and in leisure settings. We’ve had twenty years now where the majority of people in Scotland no longer breathe the toxins from cigarette smoke during their daily lives.
“But nearly a quarter of non-smokers are still exposed to tobacco smoke, and many of these exposures are happening at work – particularly in outdoor hospitality, transport settings and during visits to private homes. No one should be forced to breathe in tobacco smoke while doing their job.
“Although exposure levels today are typically much lower than before 2006, repeated low-level exposure still carries health risks. If we want to achieve Scotland’s ambition of reducing smoking to below five per cent by 2034, we need renewed focus on protecting workers and tackling the widening inequalities in home exposure.”
The research also examined smoking rules inside homes between 2012 and 2024. The proportion of smoke-free homes increased from 75.2% to 90.2%, equating to an estimated 380,000 additional smoke-free households across Scotland.
However, inequality has widened substantially. Homes in the most deprived communities are now more than ten times more likely to permit smoking indoors than those in the least deprived areas - more than double the inequality gap recorded in 2012.
The researchers say that extending smoke-free protections to additional workplaces, alongside targeted cessation support and practical interventions to encourage smoke-free homes, could help reduce remaining exposure and tackle growing health inequalities.
Co-author, Dr Rachel O’Donnell of the University of Stirling’s ISMH, said: “As Scotland celebrates the 20th anniversary of its landmark smoke-free legislation, our study shows both the enduring success of the policy and the need for the next phase of action to protect those still at risk.”
Dr Garth Reid, Consultant in Public Health at Public Health Scotland, said: “Smoking is one of the biggest causes of ill health and premature death in Scotland. Thanks to the smoking ban we have historically low smoking rates in Scotland, and we’re keen to encourage more people to give up smoking as we progress to becoming smoke-free in 2034.
“Giving up smoking is one of the best things you can do for your health, and the benefits start to happen quickly – even for people who have smoked for a long time. 
“Whether you’re ready to stop, or just beginning to think about it, the NHS Scotland stop smoking service, Quit Your Way, and your local pharmacy are here to help you stop smoking and stay stopped in a way that is right for you.”
Public Health Minister Jenni Minto said: “Banning smoking in indoor public places was a landmark moment for Scotland and one we can all be proud of.
“Since 2006, cigarette smoking has almost halved. To support people to quit we fund NHS smoking cessation services across Scotland, with more than 30,000 quit attempts recorded last year with their help.

“I’m pleased the Tobacco and Vapes Bill, which is in its final stages, provides new powers to Scottish Ministers to expand existing smoke-free spaces as well as create vape- and heated tobacco-free spaces. This will help ensure we meet our target of a tobacco-free Scotland by 2034 and further reduce exposure to health-harming products.”