Tobacco remains the leading cause of preventable mortality, morbidity and of health inequalities in many countries, including the UK. Eighty thousand people die every year in England from smoking.1 Many more suffer terrible disability. Tobacco control remains a public health priority.2 Smoking still kills.

In this context anything which could reduce this toll deserves serious consideration, just as any risks of undermining recent tobacco control successes need to be properly understood.

It is disappointing then that the debate on electronic cigarettes (also known as electronic nicotine delivery systems (ENDS) or nicotine vapourisers) has become characterised more by heat than light. There has been so much focus on these devices that we risk losing our focus on what we know works—a comprehensive strategy to reduce smoking prevalence.3 We must not lose, through neglect, the debate on standardised tobacco packaging or the need to further increase the price of tobacco. We need to move away from fixed positions to some key principles against which we can debate the evidence.

The first principle must be to ask whether electronic cigarettes are safe. First do no harm. Compared with smoking tobacco it is very clear that electronic cigarettes are much safer. Even though it is not difficult to be safer than a product which will kill half of its regular users, this message must not be lost. However, it is equally true to say that electronic cigarettes are not without harm.4 The vapour from some of these devices has been shown to contain ultrafine particles and carcinogens. There is little doubt that there is a risk of harm to …