Roughly a third of British smokers trying to quit were using e-cigarettes, a new survey from the University College London, claims. That is twice as many people as those who use government-approved nicotine gums, lozenges, and patches. Similar data is not available in the U.S. E-cigaretts are metal tubes that heat liquids usually laced with nicotine and then deliver a vapor when sucked. While they are banned from marketing themselves in the U.S. as smoking cessation devices, e-cigarette manufacturers have increasingly seen their devices popularity skyrocket for just that purpose. The U.S. market for “vapor devices” grew in 2014 by 40-50 percent to $3 billion.