Teenagers who start vaping are 2½ times as likely to become regular smokers within a year, a study has found. A study of 10,000 12- to 17-year-olds found e-cigs are a gateway to the real thing. And other smoking alternatives including hookahs or smokeless tobacco trigger conventional smoking just as quickly, researchers discovered. At the beginning of the study, none of the youngsters had smoked a cigarette. When they were interviewed again 12 months later, it was found those who tried e-cigs were now 2.53 times more like to have become smokers.