Non-smokers’ exposure to second-hand smoke has reduced by 97% in the last two decades, according to a study.
And the number of people who have not been exposed to smoke at all has risen sixfold, researchers found.
Experts, led by researchers from the University of Sterling, examined the levels of cotinine, which accumulates in the body as a result of tobacco exposure, in groups of Scottish people at 11 time points between 1998 and 2016.
They examined data obtained through Scottish Health Surveys on the levels of cotinine in non-smokers’ saliva.
The average amount of the biomarker for exposure to tobacco smoke reduced by 97.2% between 1998 and 2016, according to the study, published in the journal Tobacco Control.
Meanwhile, the percentage of non-smoking adults who had no detectable cotinine in their saliva increased from 12.5% in 1998 to 81.6% in 2016.
The authors wrote: “Scotland has witnessed a dramatic reduction in second-hand smoke exposure in the past two decades.”
But they cautioned that there are still nearly one in five non-smoking adults who have measurable exposure to second-hand smoke on any given day.
The time period studied includes the introduction of smoking bans across the UK which prohibited smoking in public places.
The authors said that across the world, second-hand smoke is a major cause of ill health and causes around 600,000 deaths annually.
Dr Sean Semple, associate professor at the University of Stirling’s Institute for Social Marketing, Faculty of Health Sciences and Sport, said: “The proportion of non-smokers who have no measurable evidence of cotinine in their saliva has increased at almost every survey year and now stands at more than four out of every five adults.
“However, that still means nearly one-fifth of non-smoking adults experience regular exposure to second-hand smoke.
“The work shows just how far Scotland has come in tackling exposure to second-hand smoke in the past two decades.
“We’ve come a long way and these figures suggest that policies and changes in how we treat smoking mean that about 2.3 million additional adults in Scotland are no longer breathing in second-hand smoke compared to the situation in 1998.
“While this is great news, we now need to work even harder on making sure that we protect the remaining 600,000 non-smokers in Scotland who continue to be exposed to second-hand smoke on a regular basis.”
Commenting on the study, Sheila Duffy, chief executive of the charity ASH Scotland (Action on Smoking and Health), said: “It is established scientific fact that second-hand tobacco smoke is harmful to health and is associated with a range of illnesses. So I am delighted to see the huge reductions in second-hand smoke exposure in Scotland.”