An estimated 2.55 million U.S. middle and highschool students reported using e-cigarettes in the course of the early a part of this yr, health officials said on Thursday, a level they described as concerning.

One in 4 of those students said they used e-cigarettes every day, in line with a national survey conducted between Jan. 18 and May 31, the U.S. Food and Drug Administration and the Centers for Disease Control and Prevention (CDC) reported on Thursday.

“Adolescent e-cigarette use in america stays at concerning levels, and poses a serious public health risk to our nation’s youth,” Brian King, director of FDA center for tobacco products said in an announcement.

Amongst students who reported e-cigarette use, nearly 85% said they used flavored versions and greater than half disposable e-cigarettes.

“This study shows that our nation’s youth proceed to be enticed and hooked by an expanding number of e-cigarette brands delivering flavored nicotine,” said Deirdre Kittner of the CDC’s office on smoking and health.

The survey suggests that e-cigarette use is up from last yr but down significantly from 2019 and 2020 levels. The CDC, nonetheless, cautioned against comparing the outcomes to previous years due to a change in how the information was collected.

Juul Labs Inc’s e-cigarettes dropped out of the highest list of brands favored by teens, the survey found, with Puff Bars, British American Tobacco Plc’s Vuse or Hyde reported as the most well-liked brands.

The FDA since 2016 has sought to crack down on fruity,sweet-flavored e-cigarettes that hook teenagers on nicotine. In January 2020, the agency banned all flavors except tobacco and menthol in Juul and other cartridge-based e-cigarettes.

A U.S. federal appeals court in June placed on hold an FDA ban on the sale of Juul’s e-cigarettes, after the corporate argued the order would cause the corporate “irreparable harm.”

Nearly all the students who accomplished the most recent online survey did so while in classrooms, just like how the information was collected in 2019, when 5.4 million students reported using e-cigarettes, and 2020, when that number was 3.6 million.

Last yr, an estimated 2.06 million teens reported current e-cigarette use, but nearly half of respondents took the survey remotely moderately than while in class. The study’s authors warned last yr and again this yr that the 2021 data was not comparable to other years.