The rate at which teens are vaping marijuana has doubled since 2013, a new study found.

The study, published Monday in JAMA Pediatrics, analyzed 17 studies conducted throughout Canada and the United States that involved nearly 200,000 adolescents. The study found that teens in their senior year of high school were most likely to be vaping marijuana compared to younger adolescents.

A study published in March found teens were about twice as likely to report “wheezing or whistling” in the chest after vaping marijuana compared to when they smoked cigarettes or e-cigarettes.”Without a doubt, cigarettes and e-cigarettes are unhealthy and not good for lungs.

However, vaping marijuana appears even worse,” study author Carol Boyd, professor emerita and codirector of the Center for the Study of Drugs, Alcohol, Smoking & Health at the University of Michigan in Ann Arbor told CNN in a prior interview.

Get the full story at cnn.com.