JUDGED by their waistlines, Europeans are much healthier than Americans. More than 30% of Americans are obese, compared with 13% of Germans and under 10% of the French. But judged by their lungs, Americans are fitter than their peers across the Atlantic. Only 19% of adult Americans smoke, against 34% of Germans and 27% of Britons. Why do Europeans light up so much more?

AFP High-tar diet

David Cutler and Edward Glaeser, of Harvard University, attempt to answer this question in a recent paper*. Since they are both economists, the first thing they look at is price. Perhaps smoking is more expensive in America? Not so. Relative to other commodities, cigarettes are in fact 37% cheaper in America than they are in the European Union. You can buy a pack for $3.60 on average stateside, but you have to pay $6.25 in Britain. The French add $2.06 in tax per packet, the Americans only 86 cents.

The second explanation an economist will look for is income. Smoking rises then falls with affluence. The very poor cannot afford to smoke as much as they might like. The rich, on the other hand, don't like to smoke as much as they could, because they put a higher value on a long and healthy life. This might explain why so many more Turks (about half of them) than Americans smoke, but it can cover only about a quarter of the gap between Americans and western Europeans.

In fact, the gap is best explained by neither prices nor incomes, but by ignorance. Europeans are less likely than Americans to believe that smoking is harmful. Only 73% of Germans, for example, believe smoking is dangerous, against 91% of Americans.

The two authors conjecture that beliefs are the result of smokers' habits, not the cause of them. A person who enjoys his cigarettes has an incentive to persuade himself that they will not do him much harm. But even non-smokers in Europe are less likely than their American counterparts to believe the weed is dangerous. These differences in beliefs may account for 20-40% of the transatlantic gap, the two authors argue.

What accounts for the rest of it? Vanity is one factor the two economists do not investigate. Since smoking suppresses appetite, perhaps those svelte European waistlines are bought at the expense of their unhealthy lungs.

*“Why do Europeans smoke more than Americans?” NBER Working Paper, no.12124. Available at www.nber.org/papers/w12124