NEW YORK (Reuters) - On a recent morning, Roger Tarazon and several friends gathered a few blocks from their Queens, New York high school. Some smoked traditional cigarettes, but Tarazon and a few others puffed on electronic vaping devices.

“Sometimes I use it to relax,” the 18-year-old senior said of the device. He also uses it to perform tricks with the vapor, blowing smoke rings or creating funnels of smoke that look like miniature tornadoes.

“I don’t do it to show off,” he said. “I just do them because I’m bored.”

Tarazon’s embrace of such tricks reflects a growing trend among U.S. teenagers, whose use of e-cigarettes tripled in the last year alone. New research provided to Reuters has found that performing tricks is one of the top two reasons young users say they consider the devices cool.

Public health officials have warned for several years of the attraction of flavored nicotine liquid to teens and tweens, and have urged regulators to ban them. Consumers have a wide range of flavor choices, including menthol, single-malt scotch, cappuccino and pomegranate.

But the role of tricks in enticing young people to use e-cigarettes has not previously been explored. Now researchers are asking whether they could help hook a new generation who otherwise would not have used nicotine.

"We expected the flavors were attractive," said Suchitra Krishnan-Sarin, a psychiatry professor at the Yale School of Medicine. “But smoke tricks were a surprise to us.”

Krishnan-Sarin and her team, with funding from the National Institutes of Health, asked 5,400 Connecticut teens to identify what they found "cool about e-cigarettes?"

The top two answers were: the flavors of the vaping liquids, and the “ability to do tricks.”

Electronic devices produce much more vapor, especially when adjusted to operate at high temperatures, than conventional cigarettes, which helps facilitate the vapor tricks. Teen interest in performing them comes as “cloud competitions,” are increasing in popularity.

The contests, in which adult vapers, as they call themsleves, compete to perform the best tricks and create the biggest and densest vapor clouds, are becoming a regular feature at local vape shops. Some regional competitions offer thousands of dollars in prize money.

Thousands of videos demonstrating expert vaping and how to perform tricks have been posted on YouTube and Instagram. “Even if (teenagers) don’t attend these events they are exposed to a lot of these issues,” Krishnan-Sarin said.

ALARM OVER TEEN USE

E-cigarette use by U.S. tweens and teens tripled in 2014 to 13.4 percent from 4.5 percent in 2013, according to data released in April by the Centers for Disease Control and Prevention. Overall tobacco use during that period dropped to 9.2 percent from 12.7 percent.

The data prompted new alarm among public health advocates, who urged the Obama administration to quickly finalize proposed rules that will allow the Food and Drug Administration to regulate e-cigarettes for the first time.

Using e-cigarettes is considered less risky than smoking traditional tobacco cigarettes, which increase the likelihood of lung cancer and other disease. But several studies have found that heating the liquids used in electronic devices to very high temperatures could release formaldehyde, a carcinogen.

"If you don't smoke, if you don't use tobacco products, there is no reason to experiment with electronic cigarettes," said Maciej L. Goniewicz, a professor at the Roswell Park Cancer Institute, who has done some of the formaldehyde research.

Tarazon and other teens said their favorite tricks include something called the “dragon,” in which vapor is exhaled from both nostrils and sides of their mouth. They learn the tricks from each other or by watching online videos with demonstrations set to popular music.

Many are of cloud competitions, which started on the West Coast a few years ago but are now popular nationwide. The majority are low-key events at vape shops where winners typically are awarded devices or gift cards.

But there are also beginning to be far more serious competitions. The Vape Capitol Cloud Championship, for example, will offer $10,000 for the Biggest Cloud and the best Vape Tricks.

The competitors – mostly men in their 20s and 30s - train to increase their lung capacity by blowing up balloons and by using diving equipment and plastic breathing devices typically used after surgery. The events bar minors from competing, and often from attending, too, though there is no law prohibiting them from being part of the audience.

"We’re aware that there is a niche group that enjoys participating in vaper competitions,” said Phil Daman, president of the Smoke-Free Alternative Trade Association. “Any use of these products should be strictly limited to adults."

Chris Esker, at Fogwind Vapor in Effingham, Illinois said he'd rather not have minors attend the store's events, but he can't prevent parents from bringing their kids.

Esker converted his T-shirt store into a vape shop about a year ago. Sales have been so strong that he hopes to open this year two more stores.

"There are kids doing back flips on dirt bikes," said Esker, who began smoking at age 12 but now vapes. "There are way worse things they can be doing."

(Reporting by Jilian Mincer; Editing by Michele Gershberg and Sue Horton)