In this Friday, Oct. 4, 2019 photo, a woman using an electronic cigarette exhales in Mayfield Heights, Ohio. Only two years ago e-cigarettes were viewed as holding great potential for public health: offering a way to wean smokers off traditional cigarettes. But now Juul and other vaping companies face an escalating backlash that threatens to sweep their products off the market. (AP Photo/Tony Dejak)