WHEN France imposed a state of emergency in November, following the terror attacks in Paris, it implied some constraints on liberty. But the freedom to smoke was probably not one many observers had in mind. Fully 32% of French 17-year-olds admit that they smoke daily, and by law pupils can do so only outside school premises. Yet head teachers now fret that, by letting them out of the school gates during the day to light up, they face a greater threat: terrorism.

Improbable as it seems, the country’s biggest head-teachers’ union, SNPDEN-Unsa, wrote last month to the prime minister, Manuel Valls, demanding clarification. Did the ban still apply under the state of emergency, as the health ministry insisted? Or, given the security risk of gathering on the pavement, could head teachers make an exception, as the education ministry seemed to suggest, and allow smoking on school grounds? This, argued some, was the lesser danger. “Between a cigarette and a Kalashnikov, the risk is not the same,” said Michel Richard, a head teacher at the union.

Nobody seems to have thought of banning young people from smoking altogether. Smoking, like café culture, seems embedded in French life. Every year 350 tonnes of cigarette butts, the equivalent in weight to two blue whales, are cleared off the streets of Paris alone. Most European countries have curbed smoking over the past decade, thanks to sales taxes, public-health campaigns and stricter rules. The proportion of people who smoke has dropped by six percentage points to 20% in Britain; by 13 points to 13% in Norway, and an average of eight points across the OECD rich countries. In France, however, the figure has remained stable, at around 25%, and since 2008 rates for teenagers have gone up. Tobacco is the leading cause of preventable death in France, far ahead of alcohol or road accidents.

Successive French governments have tried to discourage the habit. Although cigarette taxes were not raised last year, as the state auditor noted disapprovingly this week, smoking has been banned in cafés and offices. In May, after years of resistance by the tobacco lobby and tabac-sellers, Marisol Touraine, the health minister, will impose “neutral packaging”. A manufacturer’s brand name will still be visible. But all packets will be henceforth sold in “unattractive” shades of mud-brown and khaki, with lurid health warnings.

The French do not exercise much. But they don’t snack, eat much junk food, or binge-drink like British teenagers. And they live longer, stay slimmer, and suffer lower rates of cardiovascular disease than most other rich countries. Yet they seem ready to ignore health warnings when it comes to smoking. Teenage girls say it keeps them from getting fat. “If you want to be with the cool kids, you hang out with the smokers outside the gate,” says one.