A top medical body maintains that using e-cigs, or vaping, is less harmful than smoking tobacco - despite research suggesting it might increase the risk of heart attacks.
Researchers at the George Washington University concluded that e-cigarettes deliver “ultrafine particles” which can trigger inflammatory reactions that harm the heart.
These are identified as the same dangerous particles that are also delivered to the blood stream by tobacco smoking.
The research is reviewed in the Journal of the Royal College of Physicians of Edinburgh by researchers from Aberdeen Royal Infirmary, which examines the use of e-cigarettes as smoking cessation aid - and recent evidence about harm associated with vaping.
An RCPE spokesman said: “It is already well established that tobacco smoking is highly risky – smoking even one cigarette a day (compared to 20 cigarettes a day) accounts for up to a third of the risk of stroke, and up to half of the risk of heart disease”.
The College, which represents physicians across the UK, signed an NHS Health Scotland consensus statement in 2017.,
It says that e-cigarettes are useful for public health and health service purposes, but only as a potential route towards stopping smoking and not as a permanent replacement.
Abhi Mathur, one of the researchers from Aberdeen Royal Infirmary, said: “Fewer people are smoking conventional tobacco cigarettes and more people are vaping.
“Smokers are asking healthcare professionals whether e-cigarettes are safe and effective for smoking cessation.
“Debate continues regarding safety of e-cigarettes, but NHS Scotland and England have concluded that vaping e-cigarettes are less harmful than smoking tobacco.”