FILE - In this Oct. 4, 2019, file photo, a woman using an electronic cigarette exhales in Mayfield Heights, Ohio. With one in four teenagers now using e-cigarettes, underage vaping is universally condemned, and the federal government considers it an epidemic. But some other researchers believe recent trends continue to show vaping’s promise as a tool to steer millions of adult smokers away from cigarettes, the nation’s leading cause of death. (AP Photo/Tony Dejak, File)