. >> call them vapers, or foggers or competitive cloud chasers... all are welcome at crystal vapor, one of thousands of vape shops across the country. since techknow first reported on the "vaping" phenomenon in 2013, the industry has taken off like wild fire. revenue is estimated to reach 3.5 billion dollars this year, doubling since 2013. according to a recent poll 10 percent of all american adults are vaping. that's an estimated 20-million people. >> when it comes to kids, while conventional tobacco smoking among them is dropping to record lows e-cigarettes are a growing concern at the centers for disease control. >> between 2013 and 2014 alone we saw a tripling in use among us high school students to the point it was about 13.5% of us high school students had used these products within the past 30 days. >> from the early generation of cigarette look-alikes techknow first reported on, personal vaporizing devices, known as mods have gone high-tech. vaping's come a long way baby! >> we've seen the shift move from pens and tanks, at least culturally,