President Donald Trump says his administration will propose banning thousands of flavors used in e-cigarettes amid an outbreak of breathing problems tied to vaping.

State and federal health authorities are investigating hundreds of breathing illnesses reported in people who have used e-cigarettes and other vaping devices. No single device, ingredient or additive has been identified.

The proliferation of vape shops in some New Jersey towns, like the college town of New Brunswick, appear to indicate a sign of how popular vaping has become among young people.

E-cigarettes were initially touted as a safer alternative to cigarette smoking. But the flavors available for vaping devices also appealed to teens and young adults. Some say that they have noticed the consequences of the nicotine.

“I’ve noticed people, my friends actually, they would get sweaty when they were trying to leave it. So just from people trying to leave smoking, that really scared me,” says Surya Sabarwan, of New Brunswick.

Dr. Avery Browne of American Family Care in South Plainfield says that recent studies have shown how vaping could make users more susceptible to the flu.

“The vapor itself can reduce the protection mechanism in the upper respiratory system as well increase your risk of developing the flu virus and other bacterial infection,” he says.

Health and Human Services Secretary Alex Azar says the Food and Drug Administration will develop guidelines to remove all e-cigarette flavors from the market, especially those favored by children.

The FDA regulates e-cigarettes and has authority to ban vaping flavors, but has resisted calls to take that step.

Instead, the agency has said it is studying the role of flavors in vaping products, including whether they help adult smokers quit traditional cigarettes.