E-cigarettes have become increasingly popular over the past 15 or so years. These small, handheld electronic devices simulate the feeling of smoking by heating a liquid to generate an aerosol -- this is commonly called "vaping." The liquid in e-cigarettes often contains nicotine, but not always. According to health officials the use of e-cigarettes among teenagers has r eached epidemic numbers , and school districts have been holding sessions to inform parents and teachers about these devices,