"We were seeing a real drop-off in youth smoking, but now we're seeing an increase," says Dr. Beth Ebel, a UW Medicine pediatrician and researcher with the Harborview Injury Prevention and Research Center.  Among teens as young as middle-school age, vaping with products that have nicotine "predisposes you to cigarette smoking later on."

Nicotine, once derived from tobacco plants to kill insects, works by altering the nervous system. "We've used it, refined it, concentrated it, and now we have a pure form of one of the most addictive substances known," Ebel says in downloadable video soundbites (2:22).