Researchers from U.S. raised questions about how electronic cigarettes will help people to quit smoking. The study, which looked at the habits of 88 smokers who also used e-cigarettes, was published as a research letter in the journal JAMA Internal Medicine on Monday, Fox News reports. It found that smokers who also used e-cigarettes were no more likely to quit smoking after a year, compared to smokers who didn't use the devices.

E-cigarettes were first introduced in China in 2004 and have since grown into a $2 billion industry. The battery-powered devices let users inhale nicotine-infused vapors, which don't contain the harmful tar and carbon monoxide in tobacco.

"We did not find a relationship between using an e-cigarette and reducing cigarette consumption," Rachel Grana, the lead researcher on the new study, told Reuters Health.

Grana and colleagues at the University of California, San Francisco analyzed 2011 survey data collected from 949 smokers. Of those, 88 reported using e-cigarettes.