For the sixth year in a row, e-cigarettes dominated students’ choice. Public health officials were concerned that despite wide-scale publicity to deter vaping, not only did the practice continue to surge, but students did not seem to be particularly alarmed about e-cigarettes.

While e-cigarettes were by far the most popular product, researchers noted that 1 in 3 users, or an estimated 2.1 million middle and high school students, also used an additional tobacco product, such as cigars and cigarettes.

Use of cigarettes and cigars among teenagers remains relatively modest. This is the first year that more high school students reported smoking cigars than traditional cigarettes, 7.6% compared to 5.8%.

Many said they don’t consider intermittent smoking of any product to be harmful. The National Youth Tobacco Survey, conducted by the Centers for Disease Control and Prevention, found that despite widespread public health efforts to deter students from vaping or turning to any tobacco product, students still reported being steeped in an environment which promotes tobacco as alluring.

Some 9 out of 10 students said they were routinely exposed to tobacco advertising or promotion. And their interest is being piqued: Even among students who never used e-cigarettes, 39% said they were curious about using e-cigarettes, and 37% were curious about smoking cigarettes.

Researchers said they were particularly concerned about the increased possibility of nicotine dependence. Dr. Robert Redfield, director of the CDC, noted that nicotine can harm the developing brain. “Youth use of any tobacco product, including e-cigarettes, is unsafe,” he said in a statement. “It is incumbent upon public health and health care professionals to educate Americans about the risks resulting from this epidemic among our youth.”

Students reported struggling to stop vaping or smoking: 57.8% reported having given serious thought to quitting, while nearly as many said they managed to do so for at least one day.

The survey was administered to 10,097 high school students and 8,837 middle school students, which is considered a representative national sample.

This article originally appeared in The New York Times .