YOUTH smoking rates have been falling for decades. But now doctors and parents in the US are sounding the alarm over a new teen trend: the fashion for vaping.

Between 2010 and 2017, the percentage of US high-school seniors (aged 17 or 18) who had used an electronic cigarette in the past 30 days jumped from 1.5 per cent to 13 per cent. Some reports suggest that the US Food and Drug Administration (FDA) has more recent unpublished data showing an even steeper rise since …