Electronic cigarettes are bad for the lungs, scientists say.
After research, it turned out that as a result of the use of electronic cigarettes, the immune system of lung cells changes, socportal.info writes.
San Francisco was the first U.S. city to ban electronic cigarettes, the BBC said.
However, in the UK they are used by the NHS to help smokers quit smoking.
They work by heating a liquid that usually contains nicotine, propylene glycol and / or vegetable glycerin, and flavors.
Users inhale produced steam that contains nicotine - addictive.
Nicotine is relatively harmless compared to many toxic chemicals in tobacco smoke, such as tar and carbon monoxide.
Nicotine does not cause cancer - unlike tobacco in regular cigarettes, which kills thousands of smokers every year.
This is why HCG has been using nicotine replacement therapy for many years to help people quit smoking. Liquid and vapor in electronic cigarettes may contain some potentially hazardous chemicals, also found in cigarette smoke, but at much lower levels.