Julien Lavandier, a Colorado State University junior, started smoking e-cigarettes as a high school sophomore. He says he’s now hooked on Juul and has been unable to quit.

John Daley/CPR News

Colorado leads 37 states surveyed for use of electronic cigarettes among high school students according to new numbers are from a CDC study. A quarter of those students said they currently used an electronic vapor product -- double the national average. Almost 6 percent say they use them frequently.

"We understood that Colorado had a high vaping prevalence, but we were surprised to see the highest in the nation," said the state health department's Alison Reidmohr, who added that the popular Juul brand appears to be driving the trend.

"We've seen some research from the Truth Foundation that shows many young people don't even understand that Juuling might be using a nicotine product, or using a tobacco product," she said.

State health officials and public health advocates warn of many potential long-term health risks and that vaping will lead to nicotine addiction in many teens. The e-cigarette industry downplays the product's long-term potential health risks.