Cannabis vaping is increasing as the most popular method of cannabis delivery among all adolescents in the U.S., as is the frequency of cannabis vaping, according to research at Columbia University Mailman School of Public Health. The study found that the frequency of vaping cannabis among adolescents from all demographic groups is reported at six or more times per month, and rising faster than occasional use. Those who vape and smoke nicotine are more than 40 times more likely to also vape and smoke cannabis.