Easily concealable and highly potent, JUUL has become the go-to vape product for high schoolers and young adults in the U.S. It’s popular enough to have its own verb, “JUULing.” (According to the Truth Initiative, 25% of the 15-to-24-year-old users surveyed call their habit JUULing instead of vaping.)

Worryingly, it seems like many young users aren’t even sure what they’re breathing in—the Truth Initiative reveals that 37% of the same surveyed youths don’t know if they’re inhaling nicotine or not. They are indeed inhaling nicotine, with JUUL itself stating that a single "pod" contains the nicotine equivalent of 200 cigarette puffs, working out to roughly a pack a day.

“It is extremely worrisome that teens and young adults do not know that when they JUUL, they are inhaling an addictive substance,” said the CEO and President of the Truth Initiative, Robin Koval. “But it’s not surprising—many young people do not purchase their own vape products, and there will not be labeling requirements indicating that products contain nicotine until August 2018.” 

Teens are using them at a higher rate than many realize. When asked by NPR roughly how many of her friends have a JUUL, 18-year-old Mil Schooley isn’t sure, but knows its pretty high.

“I wanna say like 50 or 60%? I don't know. Maybe it's just the people I know. All my friends in college have one,” the Denver resident told NPR. “It just blew up over the summer.”

The device’s sleek form factor is reportedly a big draw for high schoolers, allowing them to take discreet drags in class behind a teacher's back. 

Teens also mentally separate their habit from “real” vaping and other smokeless tobacco devices. “People who JUUL can be normal people, but people who vape are like a certain crowd,” Schooley said. “I know it's an e-cigarette, but I don't like to call it that because you can JUUL and not be addicted to nicotine. I don't smoke cigarettes, and I don't think I ever will.”

However, studies have shown that teens who vape are more likely to graduate to smoking real cigarettes.

“It's a short jump from there to combustible cigarettes [which] delivers a better hit,” said Dr. Harold Farber, a pediatrician at Texas Children's Hospital and chair of the Tobacco Action Committee for the American Thoracic Society.

Tobacco giant Philip Morris has caught wind of the shift, actually moving to quit the cigarette business entirely to focus on their line of smokeless nicotine products.