BROOKLYN - In an effort to regulate e-cigarettes, the Food and Drug Administration has included them in its tobacco regulations, reducing access to younger people.

Under the federal rules, people younger than 18 won't be able to buy e-cigarettes. Some doctors believe this is good news.

"If you're starting as an adolescent in particular, e-cigarettes are particularly dangerous because the nicotine induces nicotine receptors in the brain of an adolescent," says Dr. Alvin Strelnick, of Montefiore Medical Center.

"No one knows what propylene glycol vapor does in your lungs," says Strelnick, who says that research hasn't been done.

But Strelnick and some other health professionals believe e-cigarettes do serve a purpose. "If you're already addicted to nicotine and you became addicted by smoking cigarettes and you smoke a pack or a pack and a half or two packs a day, switching to e-cigarettes is a good step," says Strelnick.

At Smrt Vape on East Tremont Avenue, customers can purchase liquid nicotine in a variety of flavors. Owner Diego Ostolaza says he aims to help people stop smoking.