It is entirely common within economics to mention that we live in a second best world. It may well be true that x or y, or even z, would be the best policy, the best construct. But as it turns out humans and reality don’t quite allow perfection to be achieved - we’ve got to use some second best bodge to get as close as we can to our goal without ever quite reaching it.

Something that is being forgotten by the public health crowd:

England's chief medical officer has raised fears that vaping is “a ticking time bomb” which could do long-term harm, amid growing concern about the safety of e-cigarettes.

Prof Dame Sally Davies, who will stand down later this month, made the comments just before Donald Trump announced plans to ban flavoured vaping products, in a bid to discourage children from taking up the habit.

In an interview with Civil Service World, Dame Sally raised concerns about the evidence to support the safety of e-cigarettes.

Is vaping entirely safe? That’s not even the interesting, let alone important, question:

Smokers are turning back to traditional cigarettes amid health scares over vaping, US experts have warned.

Vaping has been linked to six deaths across the United States, and 380 people have been hospitalised with lung illnesses in what the US Centers for Disease Control and Prevention has called an "outbreak".

As far as reports go - so far, it’s a little murky at present - those vaping deaths are connected with a particular contaminant in a particular product, not the process itself. But imagine it wasn’t so. Imagine that it is indeed that process.

People do indeed like taking nicotine. There will be ill effects from their doing so for there are ill effects to absolutely everything that humans do. Our favourite example of this is that hundreds of Americans a year die of being tangled in their own bedsheets. We do not therefore mandate duvets.

Of course, we are extreme by current standards on these matters. If people wish to kill themselves by smoking cigarettes then it’s their lungs, their lives. This is what to be a consenting adult means.

But even if you do not share this view the idea that we’ll limit vaping because of 6 deaths as opposed to the millions from tobacco smoking is ludicrous. We really are in this second best world where harm reduction has to be the goal, not harm elimination - on the very sensible grounds that as the switch back to proper puffing shows, harm elimination isn’t possible.