Roughly 10.8 million American adults are currently using e-cigarettes, and more than half of them are under 35 years old, a U.S. study suggests. One in three e-cigarette users are vaping daily, researchers report in the Annals of Internal Medicine.

“Electronic cigarette use is also closely associated with other high-risk behaviors,” said senior study author Dr. Michael Blaha, [...] “The most common pattern of use in the U.S. is dual use, i.e. current use of both traditional cigarettes and electronic cigarettes.”