'Heat not burn' or 'heated tobacco' products are electronic devices that, unlike e-cigarettes, contain tobacco leaf and heat it to a high temperature, without setting it alight. This difference is important. Because the devices contain tobacco, they come with all the long-term health concerns of tobacco. [...] Dr. Ed Stephens, a researcher at the University of St Andrews, whose work has compared the health impact of tobacco, e-cigarettes and heat not burn products, to find out more.