While long-term health impacts from vaping remain largely unknown, e-cigarettes were viewed as a healthier alternative that could help users quit smoking when they were first launched a few years ago.

But countries around the world have been pulling electronic cigarette products from markets and restricting advertising as vaping faces increased scrutiny.

“The current situation is considered as a serious risk to public health,” South Korea’s health minister Park Neung-hoo told a briefing, citing cases of lung injuries associated with e-cigarette use in the United States.

U.S. health officials have so far reported 33 deaths and 1,479 confirmed and probable cases from a mysterious respiratory illness tied to vaping.

A pneumonia case of a 30-year old South Korean e-cigarette user was reported this month, the health ministry said.

“Children, juveniles, pregnant women, and people with pulmonary diseases, never use liquid e-cigarettes. Non-smokers, too, never use liquid e-cigarettes from now,” Park said.

Park said the government would speed up its own studies to determine if there was a scientific basis to ban sales of liquid e-cigarettes, which vaporize liquid containing nicotine.

A rival technology, which heats but does not burn tobacco, has been authorized by the U.S. Food and Drug Administration (FDA) and has avoided much of the recent regulatory crackdown globally.

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